A method for the reduction of deformation of high-strength lightweight cement concrete

This paper presents research into the deformation properties of high-strength lightweight concrete (HSLC) containing hollow aluminosilicate microspheres. A method of increasing the fracture toughness of the HSLC by using a modifier as a coupling agent on the surface of the microparticles of aggregate is proposed. Use of the hollow microspheres is proposed to produce lightweight concrete with high performance characteristics: increasing the content of spherical microparticles in the concrete composition promotes the formation of a close-packed structure with low deformation. The coefficient of fracture toughness of the HSLC was found to be comparable to that of fine-grained high-strength normal concrete and is limited by the strength characteristics of the micrometric aggregate particles. The aim was to create an active iron–silica shell on the surface of the hollow spheres, which interacts with the major components and products of cement hydration and reinforces the phase boundary. The proposed method reduced longitudinal and transverse deformations of the HSLC by 1·20–1·60 and 1·37–2·21 times respectively. The elastic modulus of the HSLC was determined to be 6·0–8·5 GPa, with a Poisson's ratio of 0·08–0·14. The nanomodifier reduced the intensity of cracking under the influence of shrinkage stresses of HSLC by 56·9%.