Development Of High Performance Foam Concrete And Its Application In Wall Panels

Foam concrete has been widely used in cast-in-site and precast composite sandwich walls, but it also has shortcomings in strength and casting stability which need to be improved.The foam concrete is mixed with glass beads and additives admixtures. Its dry density is optimized by adjusting the glass beads and foam concrete content. Its workability is improved by adding naphthalene series and polycarboxylate superplasticizer. The construction performance of foam concrete is improved by adding expansive agent. The dry densities of foam concrete (hereinafter abbreviated to A900, A700 and A500) with three optimized mix proportion are respectively 900kg/m3,700kg/m3 and 500kg/m3 were obtained by testing the fluidity, dry density and compressive strength of different composed specimens. At the same time, the law of performance under different components was analyzed. The developed foam concrete is used as the core material of sandwich wall panel. Then, the basic properties of the wall were analyzed experimentally.The research shows that:these three kinds of foam concrete with different dry densities all own good workability. The fluidities of A900 and A700 are respectively 200-210mm,215mm. They can both achieve the foam concrete self-leveling. The fluidity of A500 is 110-130mm and makes A500 pouring easily. The compressive strength of A900, A700 and A500 can respectively reach to 8.5MPa,6MPa and 2MPa which are respectively 2-3.4 times,3-5times and 1.67-2.5 times of the industry standard. The A500 is used as the core material to made sandwich wall panels which combining with panel. It has low slump and its once pouring height can reach to 1.2m. It can bond with panel very well. The flexural strength, impact resistance and seismic performance of composite sandwich wall panels are greatly improved.When adding glass beads into the foam concrete, it has very good "skeleton" effect which can not only improve the compressive strength, but also effectively enhance the stability. Furthermore, it also prevents the concrete from collapse. There exists interaction between glass beads and foam, especially when glass beads adding up to high level. In this situation, it has serious damage to the foam. Naphthalene series and polycarboxylate superplasticizer can make the mixed material more uniform, improve the workability and compressive strength of slurry. There is an optimal value of its content. The addition of expansive agent will reduce the dry density of foam concrete, improve the adhesion of core material and panel in sandwich wall panel, reduce collapse settlement because of the large pouring height and improve the once pouring height of foam concrete. But too more expansive agent leads to large internal stress, then generate cracks, and the compressive strength of foam concrete decreases.The modified foam concrete in this paper can be used in both cast-in-place composite sandwich wall panels and precast ones.