Assessment of the physical and mechanical characteristics of sand for the production of foam concrete using the two-stage foam injection method

Abstract

The article presents the results of experimental studies of the properties of quarry sand to assess their suitability for use in the production of foam concrete. The sites of quarry sand extraction in the territory of the Akmola region are analyzed and their physical and mechanical characteristics are characterized. Evaluation of the physical and mechanical characteristics of sand was made for four types of sand. The main evaluation parameters were: particle size distribution, homogeneity, shrinkage, density and moisture content of sands. The results of the study showed that the physical characteristics of sands vary depending on their type, which indicates the differences in the natural composition and properties of these materials. Evaluation of the homogeneity of the different types of sands confirms the significant differences between the types. The highest homogeneity (xmax=77.45; xmax-1=14.98; Cc=73.5%) was observed in type 1 sand, while type 4 sand shows the minimum degree of homogeneity (xmax=47.30; xmax-1=42.28; Cc=8.7%). According to the test results, the maximum values of both densities in type 2 are: ρd=1.519 g/cm2 , ρw=1.951 g/cm2 , and the minimum values of both densities in type 4 are: ρd=1.438 g/cm2 , ρw=1.894 g/cm2 . The maximum natural moisture content in Type 1 samples is vn=9.5%, while the minimum values are 7.6% and 7.2% (Type 2 and 4). The obtained private density values have a high degree of convergence because the coefficients of variation have very low values: for Type 1 sands are 0.1-0.3%; for Type 2 sands are 0.7-0.8%; for Type 3 sands are 0.5-0.7%; for Type 4 sands are 0.4-0.6% (variation of private density values of dry and wet sands, respectively). Analysis of the results of tests on the shrinkage of samples showed that the maximum shrinkage is observed for sands of type 1 equal to 15.63%, while the minimum shrinkage is characteristic of samples of type 3 and 4 (11.25% and 11.88%). Taking into account the suitability of sand for the production of foam concrete, the most preferable is Type 1 sand mined in the Eltok building sand deposit.