Early structure formation of foam concrete mix containing modifying admixture

Building Materials

Cement based foam concrete of natural aging experiences high shrinkage of foam concrete mix in the formwork and shrinkage strain when drying. When managing the microstructure of the composite, namely the change (acceleration) of the microstructure formation and reinforcement of the cement stone, significant decrease can be achieved in the values of shrinkage strain. The purpose of this research is to study the patterns of influence of the chrysotile asbestos fibers and the glyoxal crystalline on shrinkage deformations of cement based foam concrete of natural aging. The foam concrete mixture was produced by one-step technology in the laboratory mixer. Values of plastic shrinkage and plastic strength were determined during three hours after pouring the foam concrete mixture into a metal vessel. The microstructure investigation results have shown that introduction of chrysotile asbestos fibers in an amount of 2 % and glyoxal crystalline in an amount of 0.01 % by weight of cement provides a finely porous foam concrete structure with more uniform size closed pores, which are evenly distributed over the volume. Experimental studies have demonstrated that if chrysotile asbestos fibers are introduced in an amount of 2% and the crystalline glyoxal in an amount of 0.01 % by weight of cement it leads to decrease in plastic shrinkage by 40 to 29%, shrinkage when drying by 44 and 50% and growth in plastic strength by 63 and 45% respectively.