Sustainable rubberized concrete: The role of nano-titanium dioxide in enhancing mechanical and durability properties

Abstract

Concrete is among the most utilized and essential construction materials in terms of strengthening the structure. The use of natural aggregates can be reduced by using crumb rubber aggregates (RA) as a substitute. The use of RA will reduce the expense on aggregate and help in creating a sustainable environment. Nanoparticles improve the microscopic structure of concrete by filling pores present in cement paste thus reducing the cement usage in the mix. Employing nano titanium dioxide (NT) in rubber concrete (RC) helps to improve its properties. The findings showed that RA significantly alters the characteristics of the concrete; at a 15% level of fine aggregate (FA) replacement, the workability and density of the concrete mixes dropped by up to 26.53% and 5%, respectively. Concrete’s compressive, tensile, and flexural strengths decreased by 16.1%, 5.52%, and 3.1%, respectively, as a result of adding RA. However, these negative effects were successfully offset by the addition of NT. Even while workability declined, density grew. The research shows that the use of NT in RC composites enhances corrosion resistance and durability, reduces porosity, and improves permeability. The research also suggests that NT helps to smoothen pores and microcracks in concrete, resulting in enhanced resistance to elements such as water and air. This study employs analysis of variance to evaluate the mechanical and durability characteristics of rubberized concrete composites. Microstructural investigation employing field emission scanning electron microscopy examines the interfacial transition zone, hydration products, and pore structure, offering insights into the influence of NT on concrete matrix. This study offers thorough, significant information on the application of NT nanoparticles as a green and efficient additive to enhance concrete performance, and it also presents potential for additional studies in this area of study.

Graphical abstract

Keywords

durability / hydration / mechanical properties / nano titanium dioxide / recycled rubber workability

1 Introduction

The construction industry is a major consumer of natural resources and energy, leading to significant environmental degradation. The extensive use of natural resources can be avoided by finding the best alternative that can be used in construction. The increasing volume of waste generated in the form of discarded tires gives us an opportunity for recycling and reusing waste rubber in construction [1,2]. Using recycled rubber from tires promotes environmental sustainability. It also helps reduce landfill waste, making it an effective choice for construction projects [3–6]. This versatility of rubber has led to increased research and development which focuses on maximizing the benefits while minimizing the costs. This composite helps in the reduction of noise pollution and increasing energy efficiency in buildings [7,8]. Using rubber in optimal composition gives better resistance to cracking and weathering which ensures a longer lifespan of structures. Rubber-incorporated concrete faces challenges such as declination in both compressive strength (CS) and durability aspects which decreases its use in high-strength construction projects. Thus, rubber concrete (RC) is a good alternative to traditional concrete but strength loss is prominent [9,10].

Nano titanium dioxide (NT) is an organic compound vastly used in paints, coatings, and plastics due to its opacity and brightness [11]. With advancements in nanotechnology, NT has emerged as an innovative material that enhances various material properties like chemical stability, Ultraviolet protection, photocatalytic activity, etc. [12]. In addition, the incorporation of NT into composite materials enhances mechanical strength and durability. This will be helpful in the construction and manufacturing industries. Thus, NT may be used to improve the productivity of RC. NT is unique among nanoparticles for its multifunctional advantages in concrete. Its high photocatalytic activity permits self-cleaning and air-purifying capabilities, and its ultrafine size increases matrix density by lowering porosity. It functions as a nucleation site, promoting early strength growth while being chemically stable in alkaline settings. Furthermore, the white coloring enhances the visual attractiveness of concrete. NT is a highly effective addition, even at low doses. Use of this nano particle also contributes to self-cleansing properties which reduces maintenance costs and extends the lifespan of the structure paving the way for a sustainable environment [13–15].

The incorporation of NT in cement promotes the early hydration of cement. At a later age, NT appears to hinder the hydration process. This happens due to NT restricting the movement of water molecules toward the non-hydrated cement molecules [16,17]. TiO₂ also increases the pH of concrete making it more alkaline which results in increased polymerization degree of calcium-silicate-hydrate (C-S-H) gel. Enhanced degree improves the reaction between cement and aggregates. The small cement gel pores are accelerated in the presence of TiO₂ while the large capillary pores are reduced due to hydration in the presence of TiO₂ [18–20].

Previous studies have found the benefits of using rubber in concrete like enhanced energy absorption and crack resistance but a significant decrease was found in CS which was influenced by Rubber size and content of rubber used in composite [21]. A decrease in strength was observed when rubber was replaced with coarse aggregate (CA) along with an improved electric resistance of up to 87% [22]. CS is decreased by 25%, 32%, 45%, 67%, 81%, and 88% at age 28 d with 10%, 15%, 25%, 50%, 75%, and 100% CR content, respectively [23]. Another study suggests that adding rubber particles to high-performance concrete reduces its compressive and tensile strength (TS) by 18.19% and 5.56% but improves ductility when 10% of 30 mess rubber was used [24].

NT, when incorporated in concrete, enhances its photocatalytic ability improves durability and reduces pollutants (nitrogen oxides) thus contributing to self-cleaning and anti-microbial properties [25,26]. Using a significant amount of NT (3% weight fraction) in lightweight-formed concrete improves its water absorption, porosity, and drying shrinkage [27]. A study on the strength and durability of cement mortar with a varying percentage of NT (0% to 5% by weight) shows an increase in CS and resistance to alkalinity [28]. Adding NT boosts the durability of concrete by decreasing voids, enhancing mechanical properties, and reducing chloride penetration, which improves the service life and lowers maintenance costs [15]. Abdullah et al. [29] studied the effect of NT on RC. The study indicated that the CS, TS, and flexural strength (FS) of the sample was improved by 22.6%, 12.7%, and 5.1%, respectively. For the optimum dosage of 1.5 percent NT at 28 d of casting. Furthermore, the study found enhanced modulus of elasticity, increased drying shrinkage, and decreased sorptivity and porosity. Another study conducted by Pathak and Bedagkar [30] found that the CS and FS increased by 5.9% and 29% at 28 d, respectively. The study also found that the workability of the composite arose by 16% with a water–cement ratio of 0.3 and decreased for a higher percentage replacement of rubber.

Prior research has mostly concentrated on RC composites with early-age performance (up to 28 d). This study, on the other hand, focuses on how the addition of nanoparticles affects the development of strength over the long-term. The study also examines how RC behaves when exposed to high temperatures and assesses a number of durability metrics. Nondestructive testing methods have been used to obtain a thorough grasp of the interior microstructure and structural integrity. The results provide important new information on how nanoparticles improve RC composites’ mechanical, thermal, and durability properties. All things considered, this work significantly advances the field of advanced concrete technology by demonstrating the revolutionary potential of nanoparticles in creating durable, high-performance building materials.

2 Materials and methods

2.1 Materials

The materials used to prepare NT rubberized concrete (NTRC) are ordinary Portland cement (OPC Grade 43), CA, fine aggregate (FA), crumb rubber aggregate (RA), fly ash, NT, and super-plasticizer (SP) as depicted in Fig.1. Properties of cement used are given in Tab.1, validating the specifications given in IS 8112:2013 [31]. FA used for the mix preparation is found to have a fineness modulus value of 2.62 and belongs to Zone II of the grading zone, confirming IS 383:2016 [32]. CA employed is an angular, crushed aggregate having a fineness modulus of 6.5. RA made from waste rubber tires obtained from a local is used to partially replace FA at 5%, 10%, and 15% by weight [33–37]. Zone II RA is used, confirming IS 383:2016, aggregate properties, which include specific gravity, texture, and water absorption are mentioned in Tab.2. NT was incorporated in this research as partial replacements for cement at 0.5%, 1%, and 1.5% by weight [25–29]. NT was purchased from Ad Nano Technologies. The specifications of NT are given in Tab.3. Fly ash was used as an alternative to cement, having a specific gravity value of 2.2. SP used in the mix is Fosroc Auramix 400 was used to enhance the workability property of freshly prepared concrete. SP is a polycarboxylate ether-based SP. The specific gravity of SP is 1.035 at room temperature. The specifications of the SP are provided in Tab.4. Ordinary water was utilized for the preparation of the mix. All the materials were obtained from local suppliers.

2.2 Mix proportion and specimen preparation

To evaluate the effect of NT on RC, the mix design opted for the preparation of specimen was M40 designed according to IS 10262:2019 [38]. The concrete specimens were prepared by mixing a proper combination of materials which include OPC, FA, CA, SP, fly ash, and water. In addition to these materials, RA and NT are added to the mix as partial replacements for FA and OPC respectively. A conventional sample was prepared which does not contain RA and NT elements. Other samples were also prepared including partial substitution of FA by RA only and without the use of NT. The assembly of materials for RC mixes is provided in Tab.5. The table shows detailed ratios of every component, which allows a proper interpretation of the material fraction used in the research. Each mixture is named “RP-NTQ”, where “R” corresponds to RA, P represents the fraction of FA replaced by RA, “NT” signifies nano titanium dioxide and Q shows the percentage of NT added as a substitute for cement for example, “R10-NT0.5” implies that the mix contains 10% RA replacement for FA and 0.5% NT replacement for cement.

Concrete samples were prepared aligning with the specifications mentioned in IS 10262:2019 [38], IS 1199:2018 [39], and IS 516:2021 [40]. Three samples per test were prepared for each mix. Compositions for each mix are obtained from Tab.5. Mix was prepared in a drum mixer. Mixing CA (aggregate size used: 20 and 10 mm in a 60:40 ratio) and FA in the mixer. RA, OPC, and FA were then put into the mix and mixed thoroughly for one minute ensuring all ingredients were thoroughly blended. NT was added along with cement in the proportions while preparing NTRC. A water–cement ratio of 0.32 was kept throughout. An adequate quantity of SP is mixed with water. After the addition of water ingredients were mixed until a thoroughly blended mix was formed. The mix prepared was tested for workability using a slump cone test. The composite mixes formed were poured into cubical molds, with dimensions 150 mm × 150 mm × 150 mm in size which are designed specifically to conduct compression tests that assess concrete strength to withstand axial force. Cylinder samples with parameters of 100 mm diameter and 200 mm length were also constructed to test split TS. This test analyzes concrete’s strength against tensile forces. To further assess the concrete’s capability to resist bending loads, FS tests were performed. Samples with dimensions 500 mm in length and 100 mm × 100 mm cross-section were cast to test concrete for FS. The mixes prepared were put in molds and compacted to reduce voids, assuring the correct density. Molds packed with concrete as depicted in Fig.2. At 24 h prior to casting, samples were left in the curing tank maintained at room temperature for proper hydration and to achieve desired strength until the testing day.

2.3 Testing methods

The fresh concrete was tested for workability and density to get an insight into the physical characteristics of the concrete mix. The workability test was conducted according to the procedure provided by IS 1199:2019 [39]. The workability of concrete measures its adaptability during mixing and placement, highlighting how easily it can be shaped and compacted while maintaining a cohesive structure which is necessary to achieve optimal strength and durability in construction. The slump cone test determined the workability of the composite. The density of the mix was calculated using a density bucket.

The concrete specimen was tested using the non-destructive testing (NDT) technique to get a proper insight into the micropore structure properties and integrity without causing any damage to the specimen. NDT performed in this experiment were the ultrasonic pulse velocity (UPV) test and rebound hammer test (RHT). The tests were conducted following the procedure provided by IS 13311:1992 [41].

The mechanical properties of concrete were observed by conducting tests on concrete samples after a specific curing time period. Tests were performed on the hardened concrete samples that had been subjected to a water curing time of 28, 56, and 90 d following the procedure provided by IS 516:2021 [40]. The mechanical tests evaluated the concrete strength under compression, flexure, and tension for various mixes. To investigate CS, concrete specimens with dimensions 150 mm × 150 mm × 150 mm were tested on a compressive testing machine (CTM). For FS, the beams having dimensions 500 mm × 100 mm × 100 mm were tested on a flexural testing machine. A splitting TS test was performed on concrete cylinders using CTM to achieve TS of concrete. These processes provided a good insight into the mechanical toughness and endurance of concrete. The testing arrangements for testing CS, split-TS, and FS are shown in Fig.3.

The study also examined the impacts of NT and RA on the postfire behavior and durability of concrete. The durability of the specimen was tested using the acid test, sorptivity test, and rapid chloride penetration test (RCPT) after 90 d of curing. The acid attack test used a test procedure provided by ASTM C267-01 [42]. For acid attack, test samples were placed in an acidic solution containing hydrochloric acid (HCl) and sulfuric acid (SA) separately for 7 d at a maintained pH of 2 throughout. The experimental setup for the acid attack test is shown in Fig.3(d). For the sorptivity test on the specimen, the procedure given in ASTM C1585-04 [43] was adopted. The samples having a diameter of 100 mm and a height of 50 mm were used. A silicone layer was applied to the specimen’s edge which acts as water resistant. The excess silicone was removed using acetone. The top was covered with plastic wrap and the sides were sealed with duct tape. After adjusting the water level to 3 mm the specimen was placed mounting on rods made of steel. The cleaned specimen was weighed at intervals of 10 minutes and 30 min for 6 hours and then one time each day for a week. The testing arrangement to test the sorptivity is shown in Fig.3(e). RCPT was performed on cylindrical samples of dimensions 100 mm in diameter and 50 mm in thickness corresponding to the guidelines given in ASTM C1202-19 [44]. A steady direct current voltage of 60 V is applied to the assembly. The sample is placed in between two cells: one containing a 3% NaCl solution and the other in a solution of sodium hydroxide having a molarity of 0.3 M. The test lasts for six hours, and the current passing the samples is recorded at various intervals. The test design for the RCPT is described in Fig.3(f). The postfire behavior of concrete was tested at 90 d of casting. The specimens were subjected to temperatures of 200, 400, and 600 °C using an electric furnace with a heating rate of 5 °C/min [45,46]. Upon reaching the desired temperature, the temperatures were maintained for 1 h. The samples were then left to cool down on their own in the furnace before undergoing tests. The testing obtains residual strength after exposure to fire.

3 Results and discussion

3.1 Workability

The workability and fluidity of concrete are estimated by performing a slump test on the freshly prepared mix. The workability for every mix is shown in Fig.4. The slump height for the control mix with no RA and NT was found to be 94 mm. Study shows that the workability of mixes tends to decrease as the rubber in the mix increases. On replacing 5%, 10%, and 15% RA with FA, a decrease of 4, 10, and 15 mm in slump height was observed, respectively. This change in workability due to the addition of RA has also been observed in previous research [33–37,47,48]. The reduction in workability caused by the addition of rubber can be attributed to a variety of variables, including increased surface area and fineness of the crumb rubber [49], as well as increased interparticle frictional resistance due to the rough form of the rubber particles [50,51]. In the addition of NT same trend of decrease in the workability of the mix was observed in crumb rubber concrete (CRC). For constant RA content and increasing NT content workability of the mix decreases. For mix having 5% RA 0.5%, 1%, and 1.5% addition of NT, the decrease in slump values were 2, 6, and 11 mm, respectively corresponding to reference mix R5-NT0. Likely for concrete mix with 10% RA and 0.5%, 1%, and 1.5% addition of NT, a decrease of 3, 7, and 10 mm, respectively was found. For mix with 15% RA and 0.5%, 1%, and 1.5% addition of NT, a decrease of 3, 6, and 10 mm, respectively, was found. This demonstrates that NT-incorporated concrete solidifies the cement under outside stresses. Furthermore, because NT has a higher surface area and aspect ratio, it absorbs more water, requiring a larger water volume [26,27]. Furthermore, the presence of NT leads to more entrapment of air in the mixture, reducing overall workability [15].

3.2 Density

The density of freshly prepared concrete was tested using a density bucket. For different mixes, the density values are given in Fig.5. The density value for the control sample (R0-NT0) was 2339 kg/m³. Density decrease is found when FA is replaced by RA. This decrease is more for higher rubber content. The density in this study for concretes having 5%, 10%, and 15% RA (with 0% NT in the mix) were 2300, 2247, and 2222 kg/m³ which were 1.65%, 3.93%, and 4.98% less than the control mix R0-NT0. Similar decreases have also been observed in previous research conducted on RC [33–37]. The main cause of this reduction in density is the partial replacement of high-density FA by low-density RA [49,50,52]. The decrease in density was also due to an increase in air volume in concrete because of the addition of RA [51,53,54], and the concrete microstructure expands due to the presence of carbon present in RA [54]. Further on the addition of NT in CRC, an increase in density is observed, neutralizing the reduction due to the substitution of RA in the mix. The addition of 0.5%, 1%, and 1.5% of NT content, an increase of 1.23%, 2.39%, and 3.63% in concrete density, respectively was observed. This trend was also observed in previous research [55,56]. The increase in density is most likely due to NTs working as fillers in place of air voids in the cement matrix [16,17]. Adding NT particles accelerates the early hydration process of cement, resulting in a more compact microstructure [19,20].

3.3 Non-destructive testing of specimens

3.3.1 Ultrasonic pulse velocity test

The composite samples were tested after 28 d of casting. The variation of UPV for different specimens is given in Fig.6. The UPV value for the control sample was found to be 4740 m/s. A significant decrease in velocity was observed for RA replacement in the samples. For replacement of 5%, 10%, and 15% crumb rubber led to 4%, 6.75%, and 11.39%, respective decrease in velocity. This decrease is caused by the decrease in the density of concrete due to the addition of crumb rubber. A similar decrease is found in previous studies [57]. Further, the replacement of NT to the CRC mix tends to raise the UPV value. For 0.5%, 1%, and 1.5% of NT content, incorporated in CRC mix having varying RA content, an average increase of 2.1%, 4.3%, and 6.4% respectively. The main reason for this is filling of small air voids with nano material particle [18]. UPV value increases as the density of the specimen increases and decreases for the decrease in density.

3.3.2 Rebound hammer test

A RHT was done to obtain an insight into the CS of concrete by applying external loads on the sample. The test was done at 28 d of casting. The rebound number (RN) and corresponding CS values for different cube specimens are given in Tab.6. The control sample is found to have a RN of 39. The value of RN decreases as the RA content in concrete increases. For 5%, 10%, and 15% RA replacement the values of RN were 37, 36, and 34. This is due to the increased air content in CRC mixtures and the fact that RA present in concrete absorbs energy [58]. A similar pattern is observed in other studies [59]. This shows that CS tends to reduce with higher RA substitution. Specimens with 0.5%, 1%, and 1.5% of NT content showed an average increase of 2, 4, and 3 units in the RN, respectively. Thus, the CS of concrete increases with the substitution of NT particles.

3.4 Mechanical properties of concrete

3.4.1 Compressive strength

This test evaluates the combined impact of partially substituting FA with RA and cement with NTs at various percentages on the CS of concrete after curing for 28, 56, and 90 d. The testing results for samples are given in Tab.7 and Fig.7. The CS for the ordinary mix with 0% RA and 0% NT was found 44.366, 46.21, and 48.54 MPa at 28, 56, and 90 d, respectively. Furthermore, the reference mixes were prepared with 5%, 10%, and 15% RA content with 0% NT named mix R5-NT0, R10-NT0, and R15-NT0. The 28-, 56-, and 90-d CS of the mix with no NT content and 5% RA was 42.25, 44.29, and 46 MPa, respectively, thus a decrease of 3.32%, 4.14%, and 5.22% was observed. Values of 28, 56, and 90 d CS of the mix without NT and 10% RA were 38.06, 40.56, and 43.55 MPa, respectively, showing a decrease of 14.21%, 12.32%, and 10.28% in reference to the ordinary mix. The CS for the mix without NT and 15% RA at 28, 56, and 90 d were 30.02, 31.19, and 33.81 MPa, respectively, showing a decrease of 32.32%, 31.13%, and 30.34% compared to the reference specimen. This loss in CS due to the replacement of FA by RA is supported by many researches done on CRC [33–37,60–62]. The decrease in CS of concrete when RA is added is due to a weaker bond development between the cement and the rubber, attributed to the smooth and impervious texture of the rubber [49–51], or it could be a result of the predominantly elastic and deformable nature of RA [63]. The decrease in later d strength is due to low elastic modulus of RA and weaker bond between aggregates and cement paste [64].

This study shows that the CS of the CRC is increased by substituting NT. The experimental results indicate that the highest strength gain was observed at 1% NT, while further increase in NT content decrease the strength. The CS at 28 d for R5-NT0.5, R5- NT1, and R5-NT1.5 were found as 48.5, 50.66, and 49.48 MPa, which are14.82%, 19.91%, and 17.13% more than ordinary mix R5-NT0. Likely changes in the CS were found in R10-NT0.5, R10-NT1, and R10-NT1.5 corresponding to the reference mix R10-NT0, with an increase of 8.54%, 11.69%, and 9.83% and the increase in the CS of R15-NT0.5, R15-NT1, and R15-NT1.5 corresponding to the reference mix R15-NT0 were 4.48%, 9.32%, and 6.53%. These results show that for higher NT content (above 1%), a reduction in strength is observed. Maximum strength of CRC is obtained at 1% NT replacement and decreases for lower and higher ratios. Similar behavior of concrete with NT is observed in previous research [29]. The 56-day strength study on R5-NT.5, R5-NT1, and R5-NT1.5, observed an increase of 4.54%, 7.47%, and 6.86% in comparison to strength at 28 d for the same mixes. Strength increases of 2.43, 3.45, and 2.54 were observed at 90 d corresponding to 56 d strength of the same samples. Similarly, for mixes R10-NT0.5, R10-NT1, and R10-NT1.5 an increase of 3.21%, 5.45%, and 4.23% was obtained at 56 d in reference to 28 d strength. The 90-d strength values were found to increase by 2.33%, 3.15%, and 2.66% in reference to 56 d of strength. The 56 d strength for R15-NT0.5, R15-NT1, and R15-NT1.5 was increased by 2.87%, 4.56%, and 3.01% in reference to 28 d strength. The 90-d strength values were found to increase by 1.87%, 2.96%, and 2.15% compared to 56 d strength. Thus, the use of NT increases the later days’ strength of the composite. The replacement of NT in the composite adds up to the specific surface area of binding material which is helpful in hydration increasing the later strength development in the composite [65]. The enhanced cement composite strength correlates with the increased quantity of hydration products. This improvement occurs due to well-dispersed NT particles serving as extra crystallization centers for the hydration of cement in the matrix, thereby boosting the hydration. Additionally, the NT particles in the cement mixtures act as a “filler”, occupying the gaps within cement particles and helping to immobilize any “free” water. The increase in strength was observed until the 1% NT content was used in the mix. As the amount of NT increased after 1%, a significant strength decrease was observed. Increased content of NT results in the formation of aggregates of nanometric oxides which clump together in the cement mix. This aggregation ultimately decreases the CS of the resulting composites, overshadowing the previously mentioned beneficial processes [66]. The maximum CS for 90 d was observed in the mix containing 5% RA and 1% NT giving a value of 56.32 MPa.

3.4.2 Splitting tensile strength

The splitting TS test was conducted after 28 d. Cylindrical specimens were created to determine the split TS of CRC incorporated with NT. A control sample with no RA and NT was prepared along with three reference samples containing 5%, 10%, and 15% RA with no NT content. The testing observations are illustrated in Tab.7 and Fig.8. The TS of control specimen R0-NT0 (mix having 0% RA and 0% NT) was found to be 5.16 MPa, which is 11.63% of the CS of the ordinary sample. TS for the reference sample with 5%, 10%, and 15% RA was observed at 4.62, 4.15, and 3.63 MPa, respectively, with a reduction of 10.4%, 19.5%, and 29.3%. The decrease in split TS due to RA in concrete is consistent with trends reported in previous studies [33–37,67]. The reduction in split TS can be associated with irregular bond formation between the materials, which may cause the cement-rubber interface zone to function as a microcrack [52,68]. The use of NT in this experiment tends to increase the splitting TS. The TS of R5-NT1 was observed at 5.328 MPa which was the maximum strength obtained among all the specimens with an increase of 14.4% to the reference mix (R5-NT0). The results show a clear rise of strength for mix R5-NT0.5, R5-NT1, and R5-NT1.5, an increase of 9.96%, 15.4%, and 12.3%. For mix R10-NT.5, R10-NT1 and R10-NT1.5 there was an increase of 7.6%, 12.34%, and 11.32%. For mix R15-NT0.5, R15- NT1, and R15-NT1.5, an increase of 8.04%, 13.43%, and 10.32% was observed compared to control specimens R5-NT0, R10-NT0 and R15-NT0, respectively. The enhanced TS of rubberized concrete can be attributed to the ability of NT to delay crack initiation and limit crack propagation [15,67]. The study shows an increase in TS for 1% NT usage but then a decrease in strength is observed.

3.4.3 Flexural strength

The FS test is performed to determine the bending strength of concrete. The results obtained after testing are shown in Tab.7 and Fig.9. For the control concrete sample (R0-NT0), 28 d FS was observed as 7.42 MPa, which is 16.72% of the CS obtained for control concrete. The reference samples containing 5%, 10%, and 15% RA with 0% NT content were observed to experience a decrease of 6.32%, 14.48%, and 21.63% with respect to the reference mix R0-NT0. This change is similar to various past studies [33–37]. The decrease in FS due the substitution of crumb rubber can be due to the following reasons: 1) the development of a weak bond between the rubber and cement [49,50,69]; 2) the incorporation of crumb rubber reduces the stiffness or elastic modulus of the concrete, causing it to function as a pliable core within the matrix, resulting in significant stress concentration and, ultimately, a drop in strength; 3) uniform mixing of crumb rubber with the concrete matrix is not achieved [50]. The replacement of NT improves the FS of concrete. The most increase is observed at 5% RA content and 1.5% NT content mix (R10-NT1.5), which is 20.34% compared to reference mix R10-NT0. The maximum value of 8.20 MPa is obtained for the mix (R5-NT1) showing an increase of 18.03% with respect to the R5-NT0 mix. The results show that NT increases the FS of concrete. FS of composite is increased due to improved microstructure and reduced porosity of the samples [refer to microstructure], decrease in cracks, and firmly bonding hydration products [65]. The enhancement in FS observed is primarily due to the action of RA and NT, along with the densification of the concrete matrix resulting from the physical effects of NT [70].

3.5 Durability of concrete

3.5.1 Acid attack test

1) Effect of HCl on mass of samples

An acid test was performed on the sample after 90 d of casting. The percentage mass loss is given in Fig.10. The mass of the control sample was observed at 8.13 kg. A mass loss of 1.64% was observed for the control sample. Samples with 5%, 10%, and 15% rubber experienced more loss of mass. The losses incurred were 1.89%, 2.45%, and 2.98%. This trend is noted in the research conducted by Sabapathy et al. [71]. HCl acid reacts with water to form calcium chloride, increasing the intensity of ettringite formation [49,72]. The addition of NT improves the binding strength of concrete thus the mass loss was decreased for samples containing NT. Least mass loss of 1.5% was observed in sample R5-NT1.5. Similar trends are also observed in another research [73]. The addition of NT in the mix increases the specific surface area of binding material which helps in hydration increasing the later strength development in composite [65].

2) Effect of HCl on compressive strength of samples

Tests were done on the specimen to obtain CS after being weighed for loss of mass test. The strength lost in the acid test is given in Fig.11. A strength loss of 13.34% was observed for the control sample. Sample containing 5%, 10%, and 15% RA incurred a loss of 17.75%, 20.12%, and 22.34% at 90 d. This trend is also observed in previous studies [49,72,74]. The addition of NT increases the residual strength of the specimen. The least loss of 8.52% for strength was observed in sample mix R5-NT1. Samples having higher content of RA and NT exhibit higher strength loss. Strength loss was maximum for mixes containing 15% crumb rubber particles. Strength loss for sample mix R15-NT.5 was observed at 18.56%. This increase in the strength as compared to other samples is because of the filling capability of NT and increasing the hydration products [66].

3) Effect of SA on mass of samples

This test is performed at 90 d of casting. The mass loss percentage is given in Fig.12. The control sample mass was observed as 8.13 kg. A loss of 10.45% in mass was observed for the control sample. Samples with 5%, 10%, and 15% rubber experienced more losses of 12.29%, 13.45%, and 14.98%. This trend is noted in the research conducted by Sabapathy et al. [71]. The main reason for the mass loss is due to loosen particles of recycled aggregate being eroded and removed by SA. Exposure to SA leads to mass loss in the concrete samples as a result of gypsum leaching [49,72,75]. Therefore, the mass losses are relatively small compared to normal specimens, owing to the passive nature of rubber when it is subjected to SA. Furthermore, the formation of voids and microcracks in the concrete matrix, along with the hydrophobic characteristics of RA, helps to slow down the penetration of acid into the concrete matrix [34,35,72]. The substitution of NT improves the binding power of the concrete, resulting in a reduced mass loss for samples containing NT. Least mass loss of 7.87% was observed in sample R5-NT1.5. Previous studies also show the same values [73]. Incorporating nano-TiO₂ into the mix enhances the specific surface area of the binding material, which facilitates hydration and promotes later strength development in the composite [65].

4) Effect of SA on strength of samples

Samples placed in SA mix for 7 d were tested for residual CS. The loss in strength due to the SA test is given in Fig.13. A big 32.2% loss in strength was observed in the control sample. Sample with 5%, 10%, and 15% RA experienced a loss of 35.7%, 37.34%, and 39.4% at 90 d. The study results follow the previous research works [72,75–77]. SA generates ettringite which makes voids in the concrete samples and reduces the strength [72]. Gypsum leaching from the concrete samples because of SA which also results in CS loss [72]. RA creates voids at the interfacial transition zone (ITZ) resulting in weaker bonds between cement and aggregates [33–37]. Similar to the HCl test, the addition of NT increases the residual strength of the specimen. The least loss of 26.5% was observed in sample mix R5-NT1.5. Other samples show relatively higher strength loss than R5-NT1.5. Maximum strength loss R15-NT.5 was observed at 37.67%. The increase in the residual strength as compared to samples with no NT is because of the property of NT to behave like a filler in voids of concrete and increase the hydration products [66].

3.5.2 Sorptivity test

The sorptivity test is done at 90 d. Sorptivity for different specimens is given in Fig.14. For the control sample sorptivity was 0.153 mm/s^1/2. Substituting RA with FA boosts the sorptivity values. The sample having 15% RA content observed maximum sorptivity value. The maximum value obtained at 15% RA content was 0.171 mm/s^1/2. For the inclusion of 5%, 10%, and 15% RA, an increase of 7.87%, 9.81%, and 11.76% in the sorptivity values was observed. It is possible that the addition of RA increases the pores in the specimen. These pores have a tendency to hold water thus increasing the water absorption [72]. The addition of NT in the rubber mix decreases the sorptivity. A mix containing 5% RA and 1.5% NT observed the least sorptivity value of 0.141 mm/s^1/2. The particle size of NT is small thus resulting in less sorptivity and increasing the production of C-S-H gel, which shrinks the pores, hence decreasing the sorptivity [78]. Samples with higher concentrations of NT exhibited lower sorptivity [79]. This causes pores to become less interconnected, resulting in reduced absorption [38].

3.5.3 Rapid chloride penetration test

The test data on RCPT for the specimens are illustrated in Fig.15. The reference specimen recorded the highest amount of current passed, measuring 614 Coulomb at 90 d. In contrast, the incorporation of rubber in concrete led to a decrease in charge passing, with the lowest observed charges being 318 C. This represents a decrease of 48.2% compared to the control concrete specimen. These findings align with previous literature [75]. The observed reductions in charge passing with the inclusion of RA may be attributed to the formation of voids in the concrete samples caused by RA, which hinder the passage of charge [80]. Additionally, the hydrophobic and impervious nature of RA helps resist chloride penetration in concrete specimens [80,81]. The addition of NT to the mix decreases the charge passing. As the content of NT in the mix increases, the density of the mix increases, decreasing the pores and hindering the flow of charge [66,78].

3.6 Residual compressive strength at high temperatures

The decrease in residual CS for concrete specimens at exposure to higher temperatures (200, 400, and 600 °C) is given in Fig.16. The test was performed at 90 d of casting. At 5%, 10%, and 15% RA content decreased by 13.08%, 18.71%, 26.26% at 200 °C, 22.87%, 26.33%, 33.08% at 400 °C and 42.83%, 46.72%, 51.51% at 600 °C was found in CS of samples, respectively. The loss in CS is primarily due to alteration in the chemical matrix of cement and the internal stress generated by the evaporation of capillary and free water. This process causes the formation of microcracks within the concrete matrix, a conclusion that is supported by various research studies [82–84].

Substitution of NT in the matrix enhances the residual strength. A minimum decrease in residual strength was observed in mix R5-NT1.5. A similar trend was observed in previous research [85]. This can be due to the filling capability of NT allowing a very little heat transfer by decreasing the pores in the mix [66].

4 Response surface modeling (RSM) model development

RSM helps determine ideal concrete mix compositions that reduce environmental effects while achieving strength and workability requirements [86].

RSM simplifies the optimization of concrete mixes for individual applications and environmental conditions, situations by creating accurate mathematical models based on incoming data. This optimization leads to: Increased efficiency, lower material usage, and increased sustainability in concrete building projects. Empirical response-predictive models were built and validated using experimental data. The RSM model was developed with NT and RA as variables, and physical and mechanical characteristics are the corresponding responses. Linear relationships between variables and responses were determined using the generic equation in Eq. (1).

(1)\mathit{R}={\beta }_1+{\beta }_2{\mathit{X}}_1+{\beta }_3{\mathit{X}}_{2,}

where R is the response (mechanical and physical properties) of NT incorporated concrete, with β₁ as intercept, β₂ and β₃ for the coefficients of variable (RA and NT). Equations (2)–(5) represent the formulated models for responses:

(2)\begin{array}{rl}Density=& 2346.39-93.6\mathrm{R}\mathrm{A}+0.879\mathrm{N}\mathrm{T}\\ & +14.68RA\ast \mathrm{R}\mathrm{A}-0.00086\mathrm{N}\mathrm{T}\ast \mathrm{N}\mathrm{T}\\ & -0.0845RA\ast \mathrm{N}\mathrm{T},\end{array}

(3)\begin{array}{rl}CS=& 48.74+0.16\mathrm{R}\mathrm{A}+0.1641\mathrm{N}\mathrm{T}-\\ & 4.30\mathrm{R}\mathrm{A}\ast \mathrm{R}\mathrm{A}0.000524\mathrm{N}\mathrm{T}\ast \mathrm{N}\mathrm{T}\\ & -0.0539\mathrm{R}\mathrm{A}\ast \mathrm{N}\mathrm{T},\end{array}

(4)\begin{array}{rl}TS=& 5.1634-0.8247\mathrm{R}\mathrm{A}+0.01369\mathrm{N}\mathrm{T}\\ & +0.0080\mathrm{R}\mathrm{A}\ast \mathrm{R}\mathrm{A}0.000066\mathrm{N}\mathrm{T}\ast \mathrm{N}\mathrm{T}\\ & -0.001258\mathrm{R}\mathrm{A}\ast \mathrm{N}\mathrm{T},\end{array}

(5)\begin{array}{rl}FS=& 7.4579-0.865\mathrm{R}\mathrm{A}+0.02298\mathrm{N}\mathrm{T}\\ & +0.0064\mathrm{R}\mathrm{A}\ast \mathrm{R}\mathrm{A}-0.000174\mathrm{N}\mathrm{T}\ast \mathrm{N}\mathrm{T}\\ & +0.003873\mathrm{R}\mathrm{A}\ast \mathrm{N}\mathrm{T},\end{array}

where RA is taken in kg and NT in gm.

The major work in RSM is to evaluate the quality of the created model by ensuring that data values closely align with the projected line at 45° and have small uncertainty groups, indicating a strong fit. A 3D response surface map is also used to better comprehend how factors interact with the response, as it provides an understandable three-dimensional representation of the model’s features [87]. In recent research, RSM has been widely used to simulate the mechanical and durability features of sustainable concrete composites. Adamu et al. [88] used RSM to optimize high-volume fly ash concrete with plastic waste and graphene nanoplatelets, resulting in increased strength and workability. Similarly, Iqbal et al. [89] employed RSM to examine the combined effect of crumb rubber and graphene nanoplatelets in fly ash-based geopolymer concrete, and achieved substantial increases in CS and chloride resistance. Zhang et al. [90] used RSM to estimate and optimize fire resistance in rubberized geopolymer concrete containing graphene nanoplatelets. The RSM for physical and mechanical properties of NT-mixed RC were generated using Eqs. (2)–(5).

Analysis of variance (ANOVA) was performed to statistically evaluate the significance of NT content and rubber replacement levels on the mechanical properties of concrete, including CS, split TS, and FS [37].

The results showed that the inclusion of NT had a statistically significant effect on all three strength parameters (p-value < 0.05), indicating that nano-modification contributes meaningfully to strength enhancement. Similarly, rubber content also showed a significant effect, particularly on CS and FS.

The interaction between NT and rubber content was also found to be significant in some cases, suggesting that the combined influence of both variables should be considered when optimizing the mix design.

Overall, the ANOVA results confirm that both NT and rubber content are critical factors affecting the performance of rubberized concrete and support the experimental findings discussed in earlier sections. The values mentioned in Tab.8 were obtained from MINITAB Statistical Software 22.

5 Microstructure analysis using field emission scanning electron microscopy (FESEM)

FESEM was used to evaluate the effect of NT on the microstructure of rubberized concrete. Following strength testing, small pieces of concrete were removed, dried in a vacuum oven, and coated with NT layer to improve conductivity. The FESEM study revealed improved bonding between rubber particles and the cement matrix. It also showed a denser ITZ, a refined pore structure, and enhanced formation of hydration products. The increased C-S-H gel forms indicate that NT speeds up hydration, resulting in a matrix that is more compact and has fewer microcracks. These results provide credence to the idea that NT might improve the mechanical qualities and longevity of rubberized concrete. Better bonding between the rubber particles and the cement matrix was shown by the FESEM study, which also showed a denser ITZ, refined pore structure, and enhanced hydration products. This is the typical effect of using nanomaterials in cement, which can be commonly evidenced by Refs. [91–94].

FESEM images revealed a denser microstructure in concrete containing NT compared to the control mix. The nanoparticles were well-dispersed within the matrix, filling micro-voids and refining the pore structure. This contributed to improved compactness and reduced microcracks. The images are shown in Fig.17.

The ITZ around rubber particles showed better bonding in the nano-modified mix, with fewer voids and a more continuous structure through nano-bridging mechanism as stated in Ref. [95]. These microstructural improvements align with the observed gains in strength and durability.

6 Life cycle analysis

To test the environmental health and sustainability feasibility of RC applications in construction practices, CO₂ emissions and embodied energy for all concrete mixes will be presented as an idea. The metrics during the early stages of the development of industrial recycling wastes are thought to be the most highly quantifiable. The current RC is made with the help of two variables, RA and NT, while keeping all the other concrete ingredients constant. RA and NT were partial substitutes for sand and cement, respectively. The greenhouse gas emissions and energy consumption are the key indicators for the life cycle assessment (LCA).

LCA was carried out by calculating the total embodied energy and CO₂ emissions for each concrete mix sample. The embodied energy and CO₂ emissions of each concrete constituent material are estimated using accessible literature. The amount of concrete constituent materials needed to make 1 m³ of concrete is multiplied by the relevant quantities of embodied energy and CO₂ emissions. The sum of embodied energy and CO₂ emissions for each concrete constituent material yields the total embodied energy and CO₂ emissions for that concrete mix sample. Tab.9 shows the CO₂ per kg and total embodied energy (measured in MJ/kg) values for specific concrete constituent ingredients.

Fig.18 shows the effect of RA and NT contents on the CO₂ emissions. The production of 1 m³ of concrete emits 285.87 kg of CO₂, and adding 5%, 10%, and 15% RA content increases this emission by 0.12%, 0.25%, and 0.37%, respectively. The statistics indicated that including NT in RC had a minor influence on CO₂ emissions when compared to RA. The lowest CO₂ emissions were reported in concrete mixes with 0% NT component for all RA content levels (5%, 10%, and 15%). Furthermore, CO₂ emissions increased as NT concentration increased, with the highest CO₂ emission computed for a concrete mix with the highest NT percentage (1.5%). The main reason for the increase in CO₂ emission is that NT have comparatively high carbon emission compared to cement.

Fig.19 shows how the RA and NT contents impact the total embodied energy of concrete. 2017.9 MJ of energy was used to produce 1 m³ of control concrete, and adding 5%, 10%, and 15% RA content raised emissions by 1%, 2%, and 3.1%, respectively. The addition of NT marginally enhanced the embodied energy of RC mixtures. The addition of NT (1.5% substitution) increased the embodied energy by 19.9%, 14.3%, and 12.5% for concrete mixes with fixed RA levels of 5%, 10%, and 15%, respectively. The primary cause for the increase in energy is the need for additional energy to produce RA and NT.

The CO₂ emission and embodied energy results for NTRC are consistent with earlier experimental research [75,96–99]. Previous studies found that integrating NT into concrete mixes increases embodied energy and CO₂ emissions, owing to the high energy needs and carbon-intensive manufacturing processes. There is a slight increase in CO₂ emission and embodied energy in the concrete. This is due to the production process involved in production of NT. With advancements in technology and improvement in production process, CO₂ emission and embodied energy during the production of NT can be controlled. Rubber used in concrete helps in creating a sustainable environment. These findings show that using NT in sustainable concrete involves a slightly higher initial production costs but better structural performance.

7 Economic analyses

In addition to environmental and mechanical performance, evaluating the economic feasibility of NTRC is critical for practical adoption. This analysis considers the material costs of primary constituents including OPC, RA, NT, and SP, based on approximate market prices in India (2025).

The slight increase in concrete production costs with the addition of NT is primarily due to its complex manufacturing process. However, as technology advances and production techniques improve, the cost of NT is expected to decline. This reduction will support a shift toward more environmentally friendly and sustainable construction practices, without compromising the strength and performance of concrete. Tab.10 and Tab.11 gives cost analysis for the 1 m³ and Fig.20 gives cost comparison for different mixes.

8 Conclusions

The research on enhancing rubberized concrete with NT provides key insights into its physical, mechanical, and durability properties.

RC gained density when NT was added, but workability decreased. NT offset the density reduction caused by recycled aggregate, with R5-NT1.5 exhibiting a 3.63% gain above the control mix (2339 kg/m³). With increasing NT and RA, workability decreased; at 1.5% NT, the highest slump reduction was 11 mm.

UPV rose 6.4% at 1.5% NT after declining with rubber and improving with NT. Additionally, a 4-point improvement in the RHT indicated increased strength. The CS of R5-NT1 increased by 19.91% after 28 d, and this mix also had the greatest 90-d strength (56.32 MPa). The FS and TS increased by 18.03% and 15.4%, respectively.

With R5-NT1.5 exhibiting the lowest mass and strength losses in both HCl and H₂SO₄ exposures, NT enhanced acid resistance. When compared to control, sorbtivity decreased by 7.87%, while RCPT data revealed a 48.2% decrease in chloride permeability (318 C) for R5-NT1.5. At 600 °C, strength loss decreased from 51.51% (R15-NT0) to 42.83% (R5-NT1.5), indicating an improvement in heat resistance.

Key attributes depending on RA and NT content were successfully predicted using RSM. In general, NT supports the use of RC in sustainable building by improving its mechanical, thermal, and durability performance.

Future study should examine the long-term durability of NT rubberized concrete, including resistance to carbonation, chloride attack, and freeze–thaw cycles. The environmental effect, particularly microplastic discharge from rubber, should be studied using life cycle analysis. Further research into optimizing NT dose and enhanced characterization can improve knowledge of microstructural behavior and field applicability.

References

[1] OikonomouNMavridouS. The use of waste tyre rubber in civil engineering works. In: Khatib J M, ed. Sustainability of Construction Materials. Cambridge: Woodhead Publishing, 2009, 213–238

[2] TopçuI BUygunogluT. Sustainability of using waste rubber in concrete. In: Khatib J M, ed. Sustainability of Construction Materials. Cambridge: Woodhead Publishing, 2016, 597–623

[3] Bu C , Zhu D , Lu X , Liu L , Sun Y , Yu L , Xiao T , Zhang W . Modification of rubberized concrete: A review. Buildings, 2022, 12(7): 999

[4] Yehia A A . Recycling of rubber waste. Polymer–Plastics Technology and Engineering, 2004, 43(6): 1735–1754

[5] Mohajerani A , Burnett L , Smith J V , Markovski S , Rodwell G , Rahman M T , Kurmus H , Mirzababaei M , Arulrajah A , Horpibulsuk S . . Recycling waste rubber tyres in construction materials and associated environmental considerations: A review. Resources, Conservation and Recycling, 2020, 155: 104679

[6] Rigotti D , Dorigato A . Novel uses of recycled rubber in civil applications. Advanced Industrial and Engineering Polymer Research, 2022, 5(4): 214–233

[7] Xue J , Shinozuka M . Rubberized concrete: A green structural material with enhanced energy-dissipation capability. Construction and Building Materials, 2013, 42: 196–204

[8] Zhang Z , Zheng K , Zhou X . Mechanical properties of rubberized concrete and its application in green buildings. Highlights in Science, Engineering and Technology, 2022, 28: 435–444

[9] Pham T M , Elchalakani M , Hao H , Lai J , Ameduri S , Tran T M . Durability characteristics of lightweight rubberized concrete. Construction and Building Materials, 2019, 224: 584–599

[10] Arafa A , Khalid N , Farghal O , Ahmed A . Experimental characteristics of rubberized concrete. Journal of Engineering Sciences, 2022, 50(4): 248–262

[11] WuX. Applications of titanium dioxide materials. In: Ali H M, ed. Titanium Dioxide––Advances and Applications. London: IntechOpen, 2022

[12] Majeed A , Ahmed M N , Raza S R A , Jalil A , Khan A A , Ahmed A . Precursor concentration-dependent structural, optical and electrical properties of titanium dioxide nanostructures. Materials Chemistry and Physics, 2023, 304: 127786

[13] Moro C , Francioso V , Schrager M , Velay-Lizancos M . TiO₂ nanoparticles influence on the environmental performance of natural and recycled mortars: A life cycle assessment. Environmental Impact Assessment Review, 2020, 84: 106430

[14] Joshaghani A . Evaluating the effects of titanium dioxide (TiO₂) and carbon-nanofibers (CNF) as cement partial replacement on concrete properties. MOJ Civil Engineering, 2018, 4(1): 29–38

[15] GarimaRSumitGYogeshI M. Durability aspects of concrete containing nano-NT. ACI Materials Journal, 2023, 120(2)

[16] Lee B Y , Kurtis K E . Influence of TiO₂ nanoparticles on early C₃S hydration. Journal of the American Ceramic Society, 2010, 93(10): 3399–3405

[17] Chen J , Kou S , Poon C . Hydration and properties of nano-TiO₂ blended cement composites. Cement and Concrete Composites, 2012, 34(5): 642–649

[18] Cerro-Prada E , Manso M , Torres V , Soriano J . Microstructural and photocatalytic characterization of cement-paste sol-gel synthesized titanium dioxide. Frontiers of Structural and Civil Engineering, 2016, 10(2): 189–197

[19] Diamantopoulos G , Katsiotis M , Fardis M , Karatasios I , Alhassan S , Karagianni M , Papavassiliou G , Hassan J . The role of titanium dioxide on the hydration of Portland cement: A combined NMR and ultrasonic study. Molecules, 2020, 25(22): 5364

[20] Akono A T . Effect of nano-TiO₂ on C–S–H phase distribution within Portland cement paste. Journal of Materials Science, 2020, 55(25): 11106–11119

[21] Du T , Yang Y , Cao H , Si N , Kordestani H , Sktani Z D I , Arab A , Zhang C . Rubberized concrete: Effect of the rubber size and content on static and dynamic behavior. Buildings, 2024, 14(6): 1541

[22] Mohseni E , Koushkbaghi M . Recycling of landfill waste tyre in construction materials: Durability of concrete made with chipped rubber. Construction and Building Materials, 2023, 409: 134114

[23] Aslani F . Mechanical properties of waste tire rubber concrete. Journal of Materials in Civil Engineering, 2016, 28(3): 04015152

[24] Ge J , Mubiana G , Gao X , Xiao Y , Du S . Research on static mechanical properties of high-performance rubber concrete. Frontiers in Materials, 2024, 11: 1426979

[25] Hamidi F , Aslani F . TiO₂-based photocatalytic cementitious composites: Materials, properties, influential parameters, and assessment techniques. Nanomaterials, 2019, 9(10): 1444

[26] Pietrzak A , Adamus B , Langier L . Application of titanium dioxide in cement and concrete technology. Key Engineering Materials, 2016, 687: 243–249

[27] Sattar A A , Mydin M A O , Omar R . Influence of titanium dioxide (TiO₂) nanoparticles on durability properties of lightweight foamed concrete. Journal of Advanced Research in Applied Mechanics, 2023, 109(1): 122–136

[28] SrivathsaH UPrakashT MPuneethKAvinashK. Experimental study on strength and durability characteristics of mortars with TiO₂ nanoparticles. In: Menon N V C, Kolathayar S, Rodrigues H, Sreekeshava K S, eds. Recent Advances in Civil Engineering for Sustainable Communities. Singapore: Springer Singapore, 2024, 85–95

[29] Abdullah G M S , Chohan I M , Ali M , Bheel N , Ahmad M , Najeh T , Gamil Y , Almujibah H R . Effect of titanium dioxide as nanomaterials on mechanical and durability properties of rubberised concrete by applying RSM modelling and optimizations. Frontiers in Materials, 2024, 11: 1357094

[30] Pathak S S , Bedagkar S L . Study on crumb rubber concrete using GGBS & nano-TiO₂. International Journal of Engineering Research & Technology, 2021, 10(7): 160

[31] IS8112. Ordinary Portland Cement, 43 Grade––Specifications. 2nd ed. New Delhi: Bureau of Indian Standards, 2013

[32] IS383. Coarse and Fine Aggregate for Concrete––Specifications. 3rd ed. New Delhi: Bureau of Indian Standards, 2016

[33] Kansotiya M , Chaturvedy G K , Pandey U K . Influence of nano silica and crumb rubber on the physical and durability characteristics of concrete. Multiscale and Multidisciplinary Modeling, Experiments and Design, 2024, 7: 2877–2892

[34] Chaturvedy G K , Pandey U K . Influence of graphene oxide on the long-term durability behaviour of high-strength rubberised concrete. Fullerenes, Nanotubes, and Carbon Nanostructures, 2024, 32(1): 22–33

[35] Chaturvedy G K , Pandey U K . Investigating the effect of graphene oxide on the physical and mechanical properties of high-strength RC using RStudio. Multiscale and Multidisciplinary Modeling, Experiments and Design, 2024, 7: 1605–1623

[36] Chaturvedy G K , Pandey U K , Kumar H . Effect of graphene oxide on the microscopic, physical and mechanical characteristics of rubberized concrete. Innovative Infrastructure Solutions, 2023, 8(6): 163

[37] Saini R , Chaturvedy G K , Pandey U K . Examining the effects of nano iron oxide on physical and mechanical characteristics of rubberized concrete. Innovative Infrastructure Solutions, 2024, 9(6): 180

[38] IS10262. Concrete Mix Proportioning––Guidelines. 2nd ed. New Delhi: Bureau of Indian Standards, 2019

[39] IS1199. Fresh Concrete––Methods of Sampling, Testing and Analysis. New Delhi: Bureau of Indian Standards, 2018

[40] IS516. Hardened Concrete––Methods of Test (Part 1). New Delhi: Bureau of Indian Standards, 2021

[41] IS13311. Hardened Concrete––Methods of Non-Destructive Testing of Concrete Test (Parts 1 and 2). New Delhi: Bureau of Indian Standards, 1992

[42] ASTMC267-01. Standard Test Method for Chemical Resistance of Mortars, Grouts, Monolithic Surfacing and Polymer Concretes. West Conshohocken, PA: ASTM, 2001

[43] ASTMC1585-04. Standard Test Method for Measurement of Rate of Absorption of Water by Hydraulic Cement Concretes. West Conshohocken, PA: ASTM, 2004

[44] ASTMC1202-19. Standard Test Method for Electrical Indication of Concrete’s Ability to Resist Chloride Ion Penetration. West Conshohocken, PA: ASTM, 2019

[45] Pan Z , Sanjayan J G , Collins F . Effect of transient creep on compressive strength of geopolymer concrete for elevated temperature exposure. Cement and Concrete Research, 2014, 56: 182–189

[46] Pan Z , Sanjayan J G , Kong D L Y . Effect of aggregate size on spalling of geopolymer and Portland cement concretes subjected to elevated temperatures. Construction and Building Materials, 2012, 36: 365–372

[47] Assaggaf R A , Ali M R , Al-Dulaijan S U , Maslehuddin M . Properties of concrete with untreated and treated crumb rubber—A review. Journal of Materials Research and Technology, 2021, 11: 1753–1798

[48] Sheraz M , Yuan Q , Alam M , Javed M F , Rehman M F , Mohamed A . Fresh and hardened properties of waste rubber tires based concrete: A state art of review. SN Applied Sciences, 2023, 5(4): 119

[49] Bisht K , Ramana P V . Waste to resource conversion of crumb rubber for production of sulphuric acid-resistant concrete. Construction and Building Materials, 2019, 194: 276–286

[50] Hossain F M Z , Shahjalal M , Islam K , Tiznobaik M , Alam M S . Mechanical properties of recycled aggregate concrete containing crumb rubber and polypropylene fiber. Construction and Building Materials, 2019, 225: 983–996

[51] Eisa A S , Elshazli M T , Nawar M T . Experimental investigation on the effect of using crumb rubber and steel fibers on the structural behavior of reinforced concrete beams. Construction and Building Materials, 2020, 252: 119078

[52] Abdelmonem A , El-Feky M S , Nasr E S A R , Kohail M . Performance of high strength concrete containing recycled rubber. Construction and Building Materials, 2019, 227: 116660

[53] Gupta T , Chaudhary S , Sharma R K . Mechanical and durability properties of waste rubber fiber concrete with and without silica fume. Journal of Cleaner Production, 2016, 112: 702–711

[54] Chaturvedy G K , Pandey U K , Singh M P . Analyzing the behavior of graphene oxide on high-strength rubberized concrete properties using different optimization techniques. Diamond and Related Materials, 2023, 140: 110485

[55] Sattar A A , Mydin M A O , Omar R . Strength properties and electrical resistivity of nano-TiO₂ modified lightweight foamed concrete. Journal of Advanced Research in Applied Mechanics, 2023, 109(1): 103–121

[56] Florean C , Vermesan H , Thalmaier G , Neamţu B , Gabor T , Campian C , Hegyi A , Csapai A . The influence of TiO₂ nanoparticles on the physico-mechanical and structural characteristics of cementitious materials. Coatings, 2024, 14(2): 218

[57] Ma Q , Mao Z , Lei M , Zhang J , Luo Z , Li S , Du G , Li Y . Experimental investigation of concrete prepared with waste rubber and waste glass. Ceramics International, 2023, 49(11): 16951–16970

[58] Kazemi M , Madandoust R , de Brito J . Compressive strength assessment of recycled aggregate concrete using Schmidt rebound hammer and core testing. Construction and Building Materials, 2019, 224: 630–638

[59] Brozovsky J . High-strength concrete––NDT with rebound hammer: Influence of aggregate on test results. Nondestructive Testing and Evaluation, 2014, 29(3): 255–268

[60] Ho A C , Turatsinze A , Hameed R , Vu D C . Effects of rubber aggregates from grinded used tyres on the concrete resistance to cracking. Journal of Cleaner Production, 2012, 23(1): 209–215

[61] Pelisser F , Zavarise N , Longo T A , Bernardin A M . Concrete made with recycled tire rubber: Effect of alkaline activation and silica fume addition. Journal of Cleaner Production, 2011, 19(6–7): 757–763

[62] Ganjian E , Khorami M , Maghsoudi A A . Scrap-tyre-rubber replacement for aggregate and filler in concrete. Construction and Building Materials, 2009, 23(5): 1828–1836

[63] Wang R , Gao P , Tian M , Dai Y . Experimental study on mechanical and waterproof performance of lightweight foamed concrete mixed with crumb rubber. Construction and Building Materials, 2019, 209: 655–664

[64] Thomas B S , Gupta R C . Properties of high strength concrete containing scrap tire rubber. Journal of Cleaner Production, 2016, 113: 86–92

[65] WangLZhangHGaoY. Effect of TiO₂ nanoparticles on physical and mechanical properties of cement at low temperatures. Advances in Materials Science and Engineering, 2018: 8934689

[66] Jędrzejczak P , Parus A , Balicki S , Kornaus K , Janczarek M , Wilk K A , Jesionowski T , Ślosarczyk A , Klapiszewski Ł . The influence of various forms of titanium dioxide on the performance of resultant cement composites with photocatalytic and antibacterial functions. Materials Research Bulletin, 2023, 160: 112139

[67] Güneyisi E , Gesoğlu M , Özturan T . Properties of rubberized concretes containing silica fume. Cement and Concrete Research, 2004, 34(12): 2309–2317

[68] Mousavimehr M , Nematzadeh M . Predicting post-fire behavior of crumb rubber aggregate concrete. Construction and Building Materials, 2019, 229: 116834

[69] Záleská M , Pavlík Z , Čítek D , Jankovský O , Pavlíková M . Eco-friendly concrete with scrap-tyre-rubber-based aggregate—Properties and thermal stability. Construction and Building Materials, 2019, 225: 709–722

[70] Praveenkumar T R , Vijayalakshmi M M , Meddah M S . Strengths and durability performances of blended cement concrete with TiO₂ nanoparticles and rice husk ash. Construction and Building Materials, 2019, 217: 343–351

[71] Sabapathy L , Mohammed B S , Al-Fakih A , Wahab M M A , Liew M S , Amran Y M . Acid and sulphate attacks on a rubberized engineered cementitious composite containing graphene oxide. Materials, 2020, 13(14): 3125

[72] Gupta T , Siddique S , Sharma R K , Chaudhary S . Behaviour of waste rubber powder and hybrid rubber concrete in aggressive environment. Construction and Building Materials, 2019, 217: 283–291

[73] Li S , Hu M , Chen X , Sui S , Jin L , Geng Y , Jiang J , Liu A . The performance and functionalization of modified cementitious materials via nano titanium-dioxide: A review. Case Studies in Construction Materials, 2023, 19: e02414

[74] Tiwari S , Gangwar P . Evaluate the effect of acid attack on rubberised concrete using crumb tyre rubber and replacement of cement by alccofine. Materials Today: Proceedings, 2021, 47: 3778–3782

[75] Mhaya A M , Huseien G F , Abidin A R Z , Ismail M . Long-term mechanical and durable properties of waste tires rubber crumbs replaced GBFS modified concretes. Construction and Building Materials, 2020, 256: 119505

[76] Swilam A , Tahwia A M , Youssf O . Effect of rubber heat treatment on rubberized-concrete mechanical performance. Journal of Composites Science, 2022, 6(10): 290

[77] Azevedo F , Pacheco-Torgal F , Jesus C , de Aguiar J L B , Camoes A F . Properties and durability of HPC with tyre rubber wastes. Construction and Building Materials, 2012, 34: 186–191

[78] JayapalanA RLeeB YKurtisK E. Effect of nano-sized titanium dioxide on early age hydration of Portland cement. In: Bittnar Z, Bartos P J M, Němeček J, Šmilauer V, Zeman J, eds. Nanotechnology in Construction: Proceedings of the NICOM3. Berlin: Springer Berlin, 2009, 267–273

[79] Zhang R , Cheng X , Hou P , Ye Z . Influences of nano-TiO₂ on the properties of cement-based materials: Hydration and drying shrinkage. Construction and Building Materials, 2015, 81: 35–41

[80] Yasser N , Abdelrahman A , Kohail M , Moustafa A . Experimental investigation of durability properties of rubberized concrete. Ain Shams Engineering Journal, 2023, 14(6): 102111

[81] Thomas B S , Gupta R C , Panicker V J . Recycling of waste tire rubber as aggregate in concrete: Durability-related performance. Journal of Cleaner Production, 2016, 112: 504–513

[82] Ahmed W , Lim C W , Akbar A . Influence of elevated temperatures on the mechanical performance of sustainable fiber-reinforced recycled aggregate concrete: A review. Buildings, 2022, 12(4): 487

[83] Obaidat Y T , Barham W S , Abdelrahman B N . Effect of elevated temperature on the bond behavior between near surface mounted-carbon fiber reinforced polymers strips and recycled aggregate concrete. Construction and Building Materials, 2020, 251: 118970

[84] Salahuddin H , Nawaz A , Maqsoom A , Mehmood T , Zeeshan B U A . Effects of elevated temperature on performance of recycled coarse aggregate concrete. Construction and Building Materials, 2019, 202: 415–425

[85] Wu D , Wang Z , Pan Y , Huang J , Fernández-Steeger T M , Xu C , Tang X , Long Z , Tang Y . Study on the constitutive relationship between ordinary concrete and nano-TiO2-modified concrete at high temperature. Materials, 2023, 16(14): 4910

[86] Achyutha K R M , Rao V R , Chaitanya K N , Khed V C . Optimization of bentocrete parameters using response surface methodology (RSM). AIMS Materials Science, 2021, 8(2): 221–246

[87] Bheel N , Mohammed B S , Abdulkadir I , Liew M S , Zawawi N A W A . Effects of graphene oxide on the properties of engineered cementitious composites: Multi-objective optimization technique using RSM. Buildings, 2023, 13(8): 2018

[88] Adamu M , Trabanpruek P , Jongvivatsakul P , Likitlersuang S , Iwanami M . Mechanical performance and optimization of high-volume fly ash concrete containing plastic wastes and graphene nanoplatelets using response surface methodology. Construction and Building Materials, 2021, 308: 125085

[89] Iqbal H W , Hamcumpai K , Nuaklong P , Jongvivatsakul P , Likitlersuang S , Chintanapakdee C , Wijeyewickrema A C . Effect of graphene nanoplatelets on engineering properties of fly ash-based geopolymer concrete containing crumb rubber and its optimization using response surface methodology. Journal of Building Engineering, 2023, 75: 107024

[90] Iqbal H W , Hamcumpai K , Nuaklong P , Jongvivatsakul P , Likitlersuang S , Pothisiri T , Chintanapakdee C , Wijeyewickrema A C . Enhancing fire resistance in geopolymer concrete containing crumb rubber and graphene nanoplatelets. Construction and Building Materials, 2024, 426: 136115

[91] Win T T , Raengthon N , Prasittisopin L . Advanced cement composites: Investigating the role of graphene quantum dots in improving thermal and mechanical performance. Journal of Building Engineering, 2024, 96: 110556

[92] Raj A , Yamkasikorn P , Wangtawesap R , Win T T , Ngamkhanong C , Jongvivatsakul P , Prasittisopin L , Panpranot J , Kaewunruen S . Effect of graphene quantum dots (GQDs) on the mechanical, dynamic, and durability properties of concrete. Construction and Building Materials, 2024, 441: 137597

[93] Win T T , Prasittisopin L , Nganglumpoon R , Pinthong P , Watmanee S , Tolek W , Panpranot J . Chemo-physical mechanisms of high-strength cement composites with suprastructure of graphene quantum dots. Cleaner Materials, 2024, 11: 100229

[94] Win T T , Prasittisopin L , Nganglumpoon R , Pinthong P , Watmanee S , Tolek W , Panpranot J . Innovative GQDs and supra-GQDs assemblies for developing high strength and conductive cement composites. Construction and Building Materials, 2024, 421: 135693

[95] Prasittisopin L , Nganglumpoon R , Thongchom C , Panpranot J . Systematic review and thematic analysis of the utilization of carbon quantum dots (CQDs) in construction materials. Journal of Materials Science: Materials in Engineering, 2025, 20(1): 53

[96] Haroon A , Arunachalam N , Murthy A R , Iyer N R . Assessment of embodied energy in the production of ultra high-performance concrete (UHPC). International Journal of Students Research in Technology & Management, 2014, 2(3): 113–120

[97] Abdellatief M , Al-Tam S M , Elemam W E , Alanazi H , Elgendy G M , Tahwia A M . Development of ultra-high-performance concrete with low environmental impact integrated with metakaolin and industrial wastes. Case Studies in Construction Materials, 2023, 18: e01724

[98] Bhardwaj B , Kumar P . Comparative study of geopolymer and alkali activated slag concrete comprising waste foundry sand. Construction and Building Materials, 2019, 209: 555–565

[99] Middlemas S , Fang Z , Fan P . Life cycle assessment comparison of emerging and traditional titanium dioxide manufacturing processes. Journal of Cleaner Production, 2015, 89: 137–147

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