Effect of Pre-wetting Lightweight Aggregates on the Mechanical Performances and Microstructure of Cement Pastes

Abstract

The water absorption and desorption processes of different types of lightweight aggregates were studied. Subsequently, the influences of pre-wetting lightweight aggregates on compressive strength, microhardness, phase composition, hydration parameters and micromorphology of the cement pastes were investigated. The results showed that the water absorption and desorption capacities of the lightweight aggregates increased with the decrease of the densification degree. With the addition of pre-wetting lightweight aggregates, the compressive strength of the cement pastes would increase. Moreover, the enhancement effect was more obviously with the desorption capacity of pre-wetting lightweight aggregates increasing. Especially, sample S1 with pre-wetting red-mud ceramisites had the highest compressive strength, of which increased to 49.4 MPa after 28 d curing age. The reason is that mainly because the addition of pre-wetting lightweight aggregates can promote the generation of C–S–H gels in the interfacial zone, and the hydration degree of the interfacial zone increases with the water desorption of pre-wetting lightweight aggregates increasing. It is contributed to optimize the microstructure to enhance microhardness of the interfacial zone, resulting in the compressive strength of the cement-based materials improving. Therefore, the pre-wetting lightweight aggregates with high porosity and strength are the potential internal curing agents for high-strength lightweight concretes.

Keywords

pre-wetting lightweight aggregates / cement pastes / interfacial zone / compressive strength / Microstructure

References

[1] Xu ZF, Chen Z F, Yang S H. Effect of a New Type of High-strength Lightweight Foamed Concrete on Seismic Performance of Coldformed Steel Shear Walls[J]. Constr. Build. Mater., 2018, 181(30): 287-300.

[2] Chai LJ, Shafigh P, Hilmi B M. Production of High-strength Lightweight Concrete Using Waste Lightweight Oil-palm-boiler-clinker and Limestone Powder[J]. Eur. J. Environ. Civ. Eng., 2019, 23(3): 325-344.

[3] Balendran RV, Zhou F P, Nadeem A, et al. Influence of Steel Fibres on Strength and Ductility of Normal and Lightweight High Strength Concrete[J]. Build. Environ., 2002, 37(12): 1361-1367.

[4] Jensen OM, Lura P. Techniques and Materials for Internal Water Curing of Concrete[J]. Mater. Struct., 2006, 39(9): 817-825.

[5] Wang F, Yang J, Hu S, et al. Influence of Superabsorbent Polymers on the Surrounding Cement Paste[J]. Cem. Concr. Res., 2016, 81: 112-121.

[6] Jensen OM, Hansen P F. Water-entrained Cement-based Materials: II. Experimental Observations[J]. Cem. Concr. Res., 2002, 32(6): 973-978.

[7] Bentur A, Lgarashi S, Kovler K. Prevention of Autogenous Shrinkage in High-strength Concrete by Internal Curing Using Wet Lightweight Aggregates[J]. Cem. Concr. Res., 2001, 31(11): 1587-1591.

[8] Ghourchian S, Wyrzykowski M, Lura P, et al. An Investigation on the Use of Zeolite Aggregates for Internal Curing of Concrete[J]. Constr. Build. Mater., 2013, 40: 135-144.

[9] Yang YH, Wei Z A, Chen Y L, et al. Utilizing Phosphate Mine Tailings to Produce Ceramisite[J]. Constr. Build. Mater., 2017, 155: 1081-1090.

[10] Cheeseman CR, Virdi G S. Properties and Microstructure of Lightweight Aggregate Produced from Sintered Sewage Sludge Ash[J]. Resour. Conserv. Recycl., 2005, 45(1): 18-30.

[11] Karas KP, Klein M, Hupka J, et al. Utilization of Shale Cuttings in Production of Lightweight Aggregates[J]. J. Environ. Manage., 2019, 231(1): 232-240.

[12] Dondi M, Cappelletti P D M, et al. Lightweight Aggregates from Waste Materials: Reappraisal of Expansion Behavior and Prediction Schemes for Bloating[J]. Constr. Build. Mater., 2016, 127: 394-409.

[13] Chen HJ, Wang S Y, Tang C W. Reuse of Incineration Fly Ashes and Reaction Ashes for Manufacturing Lightweight Aggregate[J]. Constr. Build. Mater., 2010, 24(1): 46-55.

[14] Liu TY, Tang Y, Han L, et al. Recycling of Harmflu Waste Lead-zinc Mine Tailings and Fly Ash for Preparation of Inorganic Porous Ceramics[J]. Ceram. Int., 2017, 43(6): 4910-4918.

[15] Liu CB, Liu L B, Tan K F, et al. Fabrication and Characterization of Porous Cordierite Ceramics Prepared from Ferrochromium Slag[J]. Ceram. Int., 2016, 42(1): 734-742.

[16] Cheeseman CR, Makinde A, Bethanis S. Properties of Lightweight Aggregates Produced by Rapid Sintering of Incinerator Bottom Ash[J]. Resour., conserv. Recycl., 2005, 43(2): 147-162.

[17] Bentur A, Igarashi S I, Kovler K. Prevention of Autogenous Shrinkage in High-strength Concrete by Internal Curing Using Wet Lightweight Aggregates[J]. Cem. Concr. Res., 2001, 31(11): 1587-1591.

[18] Liu JH, Shi C J, Farzadnia N, et al. Effects of Pretreated Fine Lightweight Aggregate on Shrinkage and Pore Structure of Ultra-high Strength Concrete[J]. Constr. Build. Mater., 2019, 204(20): 276-287.

[19] Akcay B, Tasdemir M A. Optimisation of Using Lightweight Aggregates in Mitigating Autogenous Deformation of Concrete[J]. Constr. Build. Mater., 2009, 23(1): 353-363.

[20] Zhutovsky S, Kovler K, Bentur A. Effect of Hybrid Curing on Cracking Potential of High-performance Concrete[J]. Cem. Concr. Res., 2013, 54(3): 36-42.

[21] Zhang MH, Gjorv O E. Microstructure of the Interfacial Zone Between LWA and Cement Paste[J]. Cem. Concr. Res., 1990, 20(4): 610-618.

[22] Zhang MH, Gjorv O E. Penetration of Cement Paste into Lightweight Aggregate[J]. Cem. Concr. Res., 1992, 22(1): 47-55.

[23] Königsberger M, Hellmich C, Pichler B. Densification of C–S–H is Mainly Driven by Available Precipitation Space, as Quantified Through an Analytical Cement Hydration Model Based on NMR Data[J]. Cem. Concr. Res., 2016, 88: 170-183.

[24] Snoeck D, Pel L, Belie N D. Superabsorbent Polymers to Mitigate Plastic Drying Shrinkage in a Cement Paste as Studied by NMR[J]. Cem. Concr. Compos., 2018, 93: 54-62.