The polyaniline (PANI) films doped with complex acid (sulfuric acid and sulfosalicylic acid) were prepared using the potentiostatic method on bare nickel flake (NF) and flexible polyethylene terephthalate (PET)/indium tin oxide (ITO) substrates. The contents of the PANI films, surface elements, electrochromic property and electrical conductivity were characterized by energy dispersive X-ray spectrometer (EDS), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The experimental results show that differences exist among cycle stability, redox reversibility and response time of polyaniline films on these two kinds of substrates, but the electrochromic phenomenon of the PANI films is in substantial agreement. The equilibrium transmittance spectra in the visible region (400–800 nm) for the PANI film on flexible PET/ITO substrate was obtained at different applied potential from −0.4 to 1.5 V. The results show that the transmittance of the PANI film by applying voltage is adjustable in a row and has excellent electrochromic performance.

We report an organic/inorganic hybridized nanocomposite consisting of a bi-functional poly(N-vinyl)-3-[p-nitrophenylazo]carbazolyl serves as a polymeric charge-transporting and second-order nonliner optical matrix, and CdS nanoparticles as photosensitizers to manifest photorefractive (PR) effect. The unpoled PVNPAK film exhibits a second harmonic generation (SHG) coefficient of 4.7 pm/V due to the possibility of self-alignment of the azo chromophore. Significant enhancement of photoconductivity is noticed with the increase of CdS nanoparticles concentration. The photorefractive property of the polymer nanocomposites were determined by two-beam coupling (TBC) experiment. The TBC gain and diffraction efficiency of 11.89 cm⁻¹ and 3.2% were obtained for PVNPAK/CdS at zero electrical field.

The microstructure distribution rule of semi-solid AZ91D alloy treated by ultrasonic was researched, and mechanical properies of specimens before and after ultrasonic treatment were investigated further.Semi-solid AZ91D melt specimens were processed by ultrasonic under different powers, and its microstructures and mechanical properties at different sampling points in specimens were obtained. The experimental results show that the microstructure of AZ91D alloy at different sampling points under the same ultrasonic power is different in grain size and shape, and there is also great difference among their microstructures at the same sampling point under different ultrasonic powers. AZ91D alloy treated by ultrasonic can obtain increment in both tensile strength and plasticity. Under same ultrasonic power, mechanical properties of specimen at different sampling points have obvious difference, and regularity for change of mechanical properties everywhere is similar to regularity for change of grain size and shape everywhere.

To analyze the bending properties of GCr15 steel guide rail based on the elastic-plastic theory, the novel bending loading method consisting of multi-step loading and corresponding unloading was applied in three specimens with different cross section shape and different heat treatment condition. According to the experimental results, using numerical calculation software program and the numerical simulation with finite element analysis (FEA), the relationships among the maximal load and displacement on cross section shape with each step bend loading, the loading stroke with the heat treatment condition, and the loading stroke with cross section shape were gained, and also those curves were discussed qualitatively. Finally, the contrast results between the numerical simulation and experiment were carried out to study the influence about the multi-step loading on specimen. It is put forward that enlightenment for the straightening stroke in the precision linear guide rail manufacture process.

Prestressed SUS316 fibers/ZrO₂ composite was fabricated using tape casting. Causes of cracks were analyzed by classical thermo-elastic theory and finite element method in preparation process. An optimization design was carried out on SUS316 fibers’ arrangement modes by reducing residual thermal stress. Interface topography and element distribution of composite were observed, and bending strengths were tested. Results show that cracks are generated along the direction vertical to SUS316 fibers by axial thermal stress due to different thermal expansion coefficients between SUS316 fibers and zirconia, and the average cracking space is 2 mm. No macroscopic defect is found in composite with SUS316 fibers of sine distribution, and it has better interfacial binding force since interdiffusion between SUS316 and zirconia. Bending strengths of composite with 0°/0° lamination are anisotropic and that are 385.74 MPa and 500.7 MPa respectively, but that with 0°/90° lamination is isotropic and it is 433.92 MPa. Bending strength of composite is increased obviously compared with that of zirconia because the prestress of surface is compressive stress.

The Mo surface modified layer on titanium was obtained by the plasma surface alloying technique. The structure and composition of the Mo modified titanium were investigated by X-ray diffraction (XRD) and glow discharge optical emission spectroscopy (GDOES). The Mo modified layer contains Mo coating on subsurface and diffusion layers between the subsurface and substrate. The X- ray diffraction analysis of the Mo modified titanium reveals that the outmost surface of the Mo modified titanium is composed of pure Mo. The electrochemical corrosion performance of the Mo modified titanium in saliva was investigated and compared with that of titanium. The chemical corrosion performance of the Mo modified titanium in 37 °C saliva was investigated and compared with that of titanium. The experimental results indicated that self-corroding electric potentials and corrosion-rate of the Mo modified titanium were higher than that of titanium in saliva. Corrosion-rate of the Mo modified titanium was lower than that of titanium in 37 °C saliva.

VO₂/ordered mesoporous carbon (CMK-3) composites were prepared by solid-state reaction process. The microstructures were characterized by X-ray diffraction (XRD), nitrogen adsorption and desorption, field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The experimental results showed that the vanadium oxide in the composites was vanadium dioxide (VO₂) with monoclinic structure, which was artificially loaded on the outer surface of CMK-3. VO₂/ordered mesoporous carbon composites present a significantly improved capacitive performance (131 F/g) increased by 40.86% compared to that of CMK-3 carbon (93 F/g). Therefore, as-prepared VO₂/mesoporous carbon composites suggest promising applications in hybrid capacitors.

Joining experiments of CBN grains to AISI 1045 steel were conducted using Ag-Cu-Ti composite fillers containing TiX (X=B₂ or N) particles at 920 °C for 5 min. The influences of TiB₂ and TiN particles on the interfacial microstructure features between CBN and filler were investigated comparatively. The experimental results show that TiN particles are more effective than TiB₂ ones to control the interfacial reaction and particularly the resultants. Thermodynamic analysis reveals that the varied interfacial reaction induced by the addition of TiB₂ and TiN particles is mainly atttributed to the activity change of the B and Ti elements in the brazing reaction system.

Selecting H-60 PVC foam, four-axis E-glass non-woven fabric and vinyl resin, a type of innovative reinforced sandwich composite as grooved perforation sandwich (GPS) were fabricated by VIMP. The interfacial structure between the face and core of the sandwich is innovative because of the acuminate grooves in both sides of foam core and the holes perforated along core’s height. The fabrication results show that VIMP is a high-speed and cost-effective manufacturing method. The mechanical properties of the reinforced foam core were tested. The typical flexural failure modes of sandwich specimens were observed. The flexural stiffness and ultimate bearing capacity of sandwich were studied by ordinary sandwich beam theory and finite element method.

The behavior of resistance high-g impact of EMC (epoxy molding compound) with two package models, small outline package (POS) and Globtop, was evaluated by experimental method used Hopkinson bar. At 120,000 g (generated in the Hopkinson bar with widths about 70 μ s) no damage in either the POS devices or the Globtop devices was observed. In order to enhance the EMC’s ability of resistance high-g impact, buffering effect of epoxy resin was also studied. The experimental results above all show that EMC has a better performance of impact resistance at about 120,000 g, and epoxy resin can absorb the stress wave to have the protected ability. The study of this paper could serve as a basis for selection packaging materials and enhance its reliability in high-g impact environment.

AFM (atomic force microscopy) technology was applied on C-S-H (calcium silicate hydrate phase) microstructure investigation. The topographies of hydrated C3S (Tricalcium silicate) samples were firstly acquired with AFM. Accordingly, C-S-H can be identified according its pattern. Then the hydrated pssortland cement samples at different curing time were scanned with AFM. The topographies and force displacement curve were acquired and its characters at different days were summarized and analyzed. These results are very meaningful for C-S-H microstructure further investigation and cement-base material macro scale properties improvement.

Thermal diffusion (TD) salt bath chromizing of cold working dies was studied. Firstly, it obtained an ideal salt bath formula by comparing with a variety of formulas, and then obtained the influence rule of coating thickness based on studying of some process parameters. The microstructure morphologies and phase structures of the TD chromizing coating were investigated by X-ray diffraction (XRD), energy-dispersive spectrometry (EDS) and other modern analysis methods. Meanwhile, it carried out a system of testing and analysis of coating, such as hardness, wear resistance, etc.

Vanadium pentoxide, borax, boron carbide and sodium fluoride were used to grow vanadium carbide coating on die steel(Cr₁₂, Cr₁₂MoV) surface at 950 °C by TD process, which extended the life period of Cr₁₂ and Cr₁₂MoV as punching die. Kinetics of vanadium carbide coating growth was brought forward and verified by comparison of the mathematical model with the experimental results. The thickness of coating was illustrated by SEM. The chemical constituent of coating and remnants were tested by XRD. To increase the thickness, rare earths (FeSiRe₂₃) were added to the borax salt bath. The electronic probe microanalysis (EPMA) revealed that the addition of rare earths could decrease carbon concentration in the coating and increase the depth of vanadium carbide coating.

Tourmaline can promote the growth of microorganisms under the temperature less than 900 °C by experiment. However, this promotion effect will vanish at 900 °C as a result of denaturation. Through the XRD analysis the crystal form change can explain the vanishment of tourmaline’s biological promotion effect at high temperature. Therefore, tourmaline as a biological promoter was used to prepare a kind of biological promotive ceramsite with the surface area of 7.914 m²/g, pore volume of 0.1002 mg/L, superficial pH value of 7.8, Zeta potential of 25 mV, unit water absorption of 0.1365 g/g, biocompatibility of 0.023 A/g and SICE of 0.8456. The experimental results show that the biomass of biological promotive ceramsite is 3.58 times more than that of ordinary ceramsite, and the treatment effect of the biological promotive ceramsite is better than the ordinary ceramsite. These features of this new biological promotive ceramsite makes it a preferable biovector.

The conductivity property of graphite slurry infiltrated steel fiber concrete (GSIFCON) was investigated by the four-probe method. The experimental results show that the electrical resistivity of GSIFCON decreases significantly at a specific concentration of graphite, i e, the percolation concentration. A model was accordingly developed to explain its conductive mechanism, where graphite particles could be served as bridge for conductive network between unconnected fiber chains. For an application, snow melting test of GSIFCON was carried out and a simple heating power analysis was performed. The results reveal that the thermal energy produced by GSIFCON makes snow melting effectively and the electrothermal efficiency can reach approximately 20%.

Magnesium and potassium phosphate cement (MKPC) sample were prepared by mixing dead burnt MgO powder, potassium phosphate and different dosages of retarder borax to investigate the effect of borax on its hydration and hardening characteristics. The pH value, fluidity, hydration temperature and strength development of MKPC paste were investigated, and the mineralogical composition and microstructural morphology of its hydration products were analyzed. The experimental results indicated that, within a certain dosage, borax caused an endothermal effect for MKPC paste, which decreased the early hydration rate of MKPC paste, increased the fluidity of MKPC paste. Thus, strength and micro-morphology of hardened MKPC are affected. It can be concluded that borax in MKPC paste retards the early hydration rate of MKPC paste by forming a film onto surface of MgO, decreasing the temperature and increasing the pH value of the system. As borax dosage varying, different factors may dorminate the effects.

The effects of different curing systems on the properties of high volume fine mineral powder RPC (reactive powder concrete) and the appearances of hydrates were studied. The experimental results show that dry-heating curing promotes the development of pozzolanic reactivity of fine mineral powder; due to low cement content, 0.20 water-bind ratio and high reactive fine mineral powder content, the strength of RPC increases by around 200% after steam curing and subsequent dry-heating curing. Scanning electron microscopy and energy spectrum diagram showed that: after the high volume fine mineral powder RPC with 0.16 water-bind ratio underwent steam curing and dry-heating curing, there was no significant change in the appearance of hydrates; after the RPC with 0.20 water-bind ratio, the cement content of 150 kg/m³ and more steel slag powder underwent dry-heating curing, there was a certain change in the appearance of C-S-H, the structure of gel was more compact and was uniformly distributed, and the Ca/Si of C-S-H gel decreased from 1.41 to around 1.20.

Influences of polypropylene (PP) fiber and styrene-butadiene rubber (SBR) polymer latex on the strength performance, abrasion resistance of cement mortar were studied. The experimental results show that the flexural strength, brittleness index (σ_F/σ_C) and abrasion resistance can be improved significantly by the addition of PP fiber and SBR polymer latex. The relationship between the flexural strength and abrasion resistance was analyzed, showing a good linear relationship between them. The reinforced mechanism of PP fiber and SBR polymer latex on cement mortar was analyzed by some microscopic tests. The test results show that the addition of SBR polymer latex has no significant influence on the cement hydration after 7 d curing. Adding SBR polymer latex into cement mortar can form a polymer transition layer in the interfaces of PP fiber and cement hydrates, which improves the bonding properties between the PP fiber and cement mortar matrix effectively.

A new type heat storage concrete material used in solar thermal power was fabricated by using aluminates cement to be the gelatinizer, and using high heat capacity materials, such as basalt and bauxite, as aggregate, and adding high heat conductivity graphite and high efficient water reducing agent. The experimental results show the addition of graphite can improve the thermal conductivity of the concrete, the value of thermal conductivity is about 2.34 W/mK which means the obtained concrete storage material has excellent thermal properties, and it is expected to be a good heat storage material used in solar power.

The paper presented first results elaborated during the European Research Project Re-road which aims at the development of techniques for increasing the recycling rates of reclaimed asphalt. During service life surface asphalt courses are subjected to aging due to oxidation effects which causes the hardening of the binder and thereby a change in the chemical, physical and mechanical properties of the material. Surface courses often contain highly modified binders as well as special additives for improving the performance characteristics. As these layers inhibit the shortest service lives compared to other road construction layers every year high amounts of reclaimed surface asphalt are available for recycling. The question is raised how the reclaimed asphalt consisting of high quality and costly material components can be recycled for optimal added value. To analyze the asphalt mix service life performance and its recyclability during mix design a laboratory method was developed to simulate the real in-situ aging. First the effects of site aging on the binder and asphalt characteristics were presented. Three laboratory aging methods were discussed which aimed the accelerated aging which meets similar property changes as site aging. At last the effects of two different laboratory aging methods on the same SMA mixture were compared.

A dynamic shear rheometer (DSR) setup, with a modified test geometry specifically developed for the mortar, was used to conduct time and frequency domain tests. The mortar was composed of a pure bitumen, filler and fine fractions of sand. In the test setup two mounting procedures were compared and the one that delivers better test result repeatability was selected. Test results obtained from frequency domain tests were used to construct a master curve using time-temperature superposition principle (TTS). Time domain material functions were obtained from the master curve by using frequency-time domain inter-conversion. In this process a series of Kelvin-Voigt element were used. Using material parameters obtained from frequency domain results, creep-recovery tests in time domain were simulated using a Matlab program. Results show a very good agreement with experimentally obtained creep-recovery data.

Three cement pastes were prepared with the fixed water-binder ratio and different fly ash contents. The compression test and electrical resistivity measurement of the paste mixes were conducted during 48 h. The changes of the CH content and the non-evaporable water content in the cement-fly ash hydration systems with time were obtained by the thermal gravimetric analysis. The experimental results show that dilution effect of fly ash as micro-filler is dominant mechanism before 48 h, which appears to decrease in the CH content and the non-evaporable water content, also in compressive strength and electrical resistivity, with the increase of fly ash replacement. The relationships between CH content, non-evaporable water content and electrical resistivity show that electrical resistivity can be the indicators of hydration products CH and non-evaporable water. The correlation of the compressive strength f _c and the electrical resistivity ρ can be obtained as f _c=8.3429 ρ = 6.7088 for the period of 48 h. The early age compressive strength can then be predicted by electrical resistivity measurement.

A simplified procedure was described to estimate the FEL of three kinds of hot-mix asphalt concrete (HMAC) without doing any fatigue tests. The procedure required two fundamental properties of HMAC, tensile strength under different temperatures and strain rates, and flexural stiffness under different stain levels. This information can reliably be obtained in simple tests, which are the monotonic uniaxial tensile test (MUTT) and the four-point bending test (FPBT). A new parameter, the initial stress ratio R _initial, was introduced to connect these two tests, which was defined as the ratio of applied initial stress and tensile strength of the specimen. At last the FEL can be expressed as a function of the initial flexural stiffness, frequency and temperature. Obviously, this procedure has the potential to be very useful in view of long-life pavement design and time consuming traditional fatigue tests.

Effect of organo-montmorillonite (OMMT) on the morphology and aging properties of various bitumens was studied. The morphology of the binders was characterized by atomic force microscopy (AFM). The influence of OMMT on physical properties of the binders before and after long-term aging and ultraviolet (UV) aging was investigated. It was observed that the effect of OMMT on the morphology and aging properties of bitumens depended on the base bitumen. In one case, OMMT affected the dispersed phase in bitumen. In the other case, OMMT affected the bitumen matrix. In both cases, OMMT caused stiffening of the modified phase. Compared with modification of the dispersed phase, modification of the matrix phase showed an obvious improvement on the physical properties as well as the better UV aging properties of bitumens, which was opposite to the long-term aging result.

The major objective of this research was to discuss the effects of loading rate on the flexural-tension properties and uniaxial compressive strength of micro-surfacing mixture using three-point bending test and uniaxial compressive test respectively. As a preventive maintenance surface treatment on asphalt pavement, micro-surfacing was formed on the basis of the ISSA recommendation of an optimum micro-surfacing design. Tests were conducted over a wide range of temperature to investigate the difference of properties from low loading rate to a relatively high loading rate. Three-point bending test was used to study the flexural strength, strain and modulus of micro- surfacing mixture, and uniaxial compressive test was carried out to obtain the relationship between strength and the loading rate as well as temperature. The experimental results showed that flexural strength at high loading rate was larger than that at low loading rate. The flexural strength difference between low and high loading rate enlarged when the temperature rose. The flexural strain at high loading rate increased compared with results of the low loading rate. Results of the flexural modulus revealed that micro-surfacing mixture exhibited better anti-cracking characteristic at low temperature when given a relatively low loading rate. Results of uniaxial compressive test revealed that the strength difference of micro-surfacing among different loading rates increased with the increase of temperature. The logarithm relationship between the strength and loading rate over a wide range of temperature was obtained to compare the experimental and predicted values, which resulting in a reasonable consistency.

For determining the optimal percentage of RAP material in central plant hot recycling, binder was recovered from RAP by means of Abson recovery method, and properties tests of mixed binders consisting of recovered asphalt and fresh asphalt at different ratios were performed. In addition, the performances of mixture with different percentages of RAP such as rutting resistance, anti-cracking, moisture susceptibility and fatigue resistance were tested. The binder test results showed that the high temperature performance was improved with the increase of the percentage of the RAP, while the low temperature performance was declined. When the percentage of the recovered binder was less than 30%, the mixed binder could match the technical standards for fresh asphalt. Tests on the mixtures showed that rutting resistance increased gradually as RAP percentage increased, while thermal anti-cracking at low temperature and fatigue properties declined. The effect of the percentage of RAP on moisture susceptibility was limited. It is indicated that low temperature performance and fatigue properties are important for selecting the optimal percentage of RAP. Based on data obtained from binders and mixtures, it is concluded that the maximum percentage of RAP is approximately 30% without the addition of rejuvenating agent.

The objective of this study was to investigate and evaluate the rheological and moisture susceptibility of the WMA mixtures containing moist aggregates. The experimental design included the utilizations of two aggregate sources, two moisture, two anti-stripping additives, and three WMA additives and control. Several properties of the binders and mixtures were obtained including: viscosity, dynamic shear rheometer, beam bending rheometer of WMA binders, indirect tensile strength (ITS), tensile strength ratio (TSR), and flow values. The experimental results indicate that the WMA additives can result in a slight decrease in viscosity and an increase in failure temperature. In addition, the moisture susceptibility results illustrated that the mixtures containing moist aggregates generally have similar ITS values to other mixtures regardless of HMA or WMA types. Moreover, there were no significant differences in the wet ITS values of WMA mixture amongst four types of mixtures under identical conditions (same moisture and lime contents) except for the mixtures containing liquid anti-stripping additive and Asphamin additive.

The viscosity of five bitumens was measured at different temperatures and the viscosity- temperature relationship was developed to evaluate the temperature susceptibility of different bitumens. The generic fractions (i e, saturates, aromatics, resins and asphaltenes) of the bitumens were separated and tested by thin-layer chromatography with flame ionization detection (TLC-FID) and the effect of chemical compositions on temperature susceptibility of bitumens was analyzed using the linear regression method. The experimental results show that the four generic fractions play an inconsistent role in the temperature susceptibility of bitumens and the correlation degree of each fraction is somewhat different. The existence of aromatics and asphaltenes can lower the sensitivity to temperature changes whereas saturates and resins may have an adverse impact on the temperature susceptibility of bitumens. As for the correlation degrees, resins show the closest correlation with the temperature susceptibility of bitumens, then asphaltenes and aromatics, and the correlation between temperature susceptibility and saturates is relatively weak.

A kind of novel shape-stabilized phase change material (SSPCM) was prepared by using a melting intercalation technique. This kind of SSPCM was made of lauric acid (LA) as a phase change material and organophilic montmorillonite (OMMT) as a support material. And the thermal properties and morphology of the SSPCM were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electronic microscope (SEM), scanning calorimeter (DSC), and differential thermal cravimetry (TG). The DSC result shows that the phase change temperature of the SSPCM is close to that of LA, and its latent heat is equivalent to that of the calculated value based on the mass ratio of LA measured by TG. The XRD, SEM and TEM results demonstrate that the LA intercalates into the silicate layers of the OMMT, thus forming a typically intercalted hybrid, which can restrict the molecular chain of the LA within the structure of OMMT at high temperature. And consequently SSPCM can keep its solid state during its solid-liquid phase change processing.

The relationship between petrographical and physical properties of limestone, basalt, granite and gneiss was investigated. Petrographical data were quantified from polished thin sections with a polarising microscope to determine the modal composition. The properties of resistance to fragmentation and abrasion were determined by Los Angeles abrasion test and crushing test. The shape characteristic was measured by Flakiness index test. The experimental results indicate that abundance of fine- to medium-grained minerals (especially of plagioclase, quartz and feldspar) are prime, and strong micrographic intergrowth texture with interlocking grain boundaries have the great positive influence on the physical properties. It is also indicated that petrographical properties and surface texture of rocks can decide the potentiality of rocks as raw materials with high quality on resisting fragmentation and abrasion. Analysis of Integration of petrographical data and mechanical properties is ideal for the selection of aggregates used in asphalt concrete.

The coarse pore system, interfacial transition zone (ITZ) between aggregate and paste matrix and volume fraction of unhydrated cement in concrete (w/c=0.3) containing mineral admixtures were quantitatively characterized by the scanning electron microscope-backscattered electron (SEM-BSE) image analysis technique. The experimental results show that compound addition of slag and fly ash decreases the coarse porosity from 10.17% to 3.74% and the threshold diameter of coarse pore size from 345 μm to 105 μm compared with concrete (w/c=0.30) without mineral admixtures; Moreover with compound addition of fly ash and slag, the volume proportion of unhydrated cement in paste matrix is reduced by 30%, the maximum amount of coarse pores in the ITZ between aggregate and paste decreases from 13.11% to 5.57% and the thickness of ITZ is reduced by 37%, compared with concrete without mineral admixtures.

A computer-based model and method was presented to predict the time dependency of chloride diffusion coefficients in cement paste. The HYMOSTRUC3D model was applied to generate a 3D representative elementary volume (REV) of cement paste. In the simulation of microstructure, both of cement hydration and chloride binding were considered. With the simulated microstructure of cement paste, the finite element method was applied to simulate the diffusion process of chloride through the saturated cement paste. Based on the Fick’s first law, the chloride diffusion coefficient can be calculated. In this method, the influences of age and w/c ratio on the chloride diffusion coefficient were evaluated. The simulated chloride diffusivities with various w/c at different time were compared to experimental data obtained from the literature. The experimental results indicate that the chloride diffusion coefficient decreases with the increase of time and the decrease of w/c ratio. The trend of simulated relationship (diffusion coefficient vs time, diffusion coefficient vs w/c ratio) fits very well with the experiments.

Low field NMR technique was applied to investigate the hydration of cement pastes with different water to cement ratios or addition of superplasticizer. As a nondestructive method, this technique can be used to monitor the hydration kinetics process by following the changes of longitudinal relaxation time (T ₁) of water constrained in the pastes. The experimental results indicate that the T ₁ distributions of water in the fresh paste normally exhibite bimodal distribution, where the large peak is corresponding to the free water while the small one is contributed by the water stored in the flocculations. Time dependence of the weighted average T ₁ has a good agreement with the hydration process and could be divided into four stages, i e, initial period, dormant period, accelerated period and steady period. The hydration mechanism of each stage was described based on the theory of cement chemistry. In addition, the total signal intensity, which is proportional to the content of the physically bound water in the samples, decrease successively during the hydration reflecting the consumption of physically bound water by hydration reactions.

To enhance the performance of mix granulate road base courses by cement treatment. The mechanical properties of cement treated mix granulate (CTMG) were studied, which was designed with 65% crushed masonry and 35% crushed concrete by mass. The central composite design was employed to prepare specimens with different levels of cement content and degree of compaction. All specimens were cured in a fog room at 20°C for a specific number of days. The compressive strength and the indirect tensile strength were determined through the monotonic compression and indirect tension tests. Effective prediction models for the mechanical properties of CTMG, in relation to the cement content, the degree of compaction and the curing time, were successfully established for a mix containing 65% crushed masonry and 35% crushed concrete by mass.

The effect of limestone powder and fly ash on magnesium sulfate resistance of mortar was studied by testing on the strength, expansion and hydration products of the specimens stored in MgSO₄ solution at certain periods. The experimental results show that the strength of mortar stored in MgSO₄ solution increases a little before 28 d, but decreases fast subsequently. The more the contents of limestone powder and fly ash, the less the strength losses. Mortar swells in the MgSO₄ solution with the soaking time. And the more the contents of limestone powder and fly ash, the less the expansion rate is. The expansion or strength loss of mortars results from the expansion of gypsum, as well as the loss of Ca(OH)₂ and other hydration products of cement. The magnesium sulfate resistance of the mortars containing limestone powder and fly ash is high.

Early age hydration of cement paste was investigated by monitoring the ultrasonic propagation velocity and simulated with the numerical model CEMHYD3D. The ultrasonic velocity of the P-wave was recorded during the first 24 hours of the hydration process and its evolution was analyzed. It is shown that the UPV method is an effective, accurate and non-destructive method for monitoring the early age hydration process of cement paste. The early age hydration process can be classified as four periods, which are the dormant period, acceleration period, deceleration period and stabilization period. Higher w/c ratios result in lower UPV, and delay initial setting time due to the decreased solid volume. The change of UPV is clearly related to the hydration degree of cement particles.

Experiment was carried out to simulate different loading level elements under coupling of stray current and 5% chlorine salt solution. When calculating corrosion of reinforcement, the influence of loading should be considered based on the first law of Faraday electrolysis. The current density of the corrosion was measured by the linear polarization resistance method. The function of corrosion current density was obtained by nonlinear fitting method, and the influence coefficient of loading level to electrochemical equivalent was obtained base on the function of corrosion current density. The experimental results show that the corrosion current density increases with stress ratio of concrete structures. The reinforcement corrosion weight can be calculated through the influence coefficients of electrochemical equivalent and the result is in line with the actual situation.

To study the relationship between material composition, curing conditions and strength development, the study simulated high-strength precast concrete pile production, and a high-strength mortar up to 90 MPa was designed and a hot-water pool was built for concrete curing. The major point of the study was to achieve a high early strength by using cement/metakaolin systems without autoclave curing with high-pressure steam. By means of XRD and thermal analysis, the progress of the hydration of the cement pastes blended with metakaolin was characterized. The main results indicate that high strength can be obtained at early age by the use of metakaolin and thermal treatment (hot-water curing). The improvement in strength of mortars with metakaolin can be explained by an increase in the amount of C-S-H and C-S-A-H hydrated phases and a decrease in the amount of calcium hydration(CH). Further more, a decrease in Ca/Si ratio of the matrix was observed from the results of EDX analysis, which also leaded to an improvement of the compressive strength. These results are of great importance for the high-strength precast concrete manufacturing industry.

In the present work, a computer model was developed to simulate random packing of aggregates. For the sake of simplicity, two dimensional situation was considered and all of the aggregates in concrete were assumed as ellipse. 2D elliptical models of random packing were firstly demonstrated in periodic boundary condition. In addition, the ellipse random packing model was employed for the influence of aspect ratios on the packing fraction of ellipses. The modeling results demonstrate that the packing fraction of ellipses firstly increases then drops down with increasing aspect ratio. The maximal random packing fraction is 0.66 when aspect ratio is 1.04 in the periodic boundary condition.

By incorporation of fly ash or silica fume into magnesium oxychloride (MOC) cement, a high water resistance material can be formed for successful industrial applications. The influences of fly ash and silica fume on water-resistant property were investigated by SEM and EDS. It is found that the incorporation of fly ash or silica fume can improve the water-resistance of the MOC. The improvement of the water resistance of the MOC incorporated with fly ash or silica fume may be attributed to the alumino-silicate 5·1·8 gel or silicate 5·1·8 gel.