Microscopic Analysis of Cementitious Sand and Gravel Damming Materials.

The mechanical properties of cementitious sand and gravel damming material have been experimentally determined by means of microscopic SEM (Scanning Electron Microscopy) image analysis. The results show that the combination of fly ash and water can fill the voids in cemented sand and gravel test blocks because of the presence of hydrated calcium silicate and other substances; thereby, the compactness and mechanical properties of these materials can be greatly improved. For every 10 kg/m³ increase in the amount of cementitious material, the density increases by about 2%, and the water content decreases by 0.2%. The amount of cementitious material used in the sand and gravel in these tests was 80-110 kg/m³, the water-binder ratio was 1-1.50. Moreover, the splitting tensile strength was 1/10 of the compressive strength, and the maximum strength was 7.42 MPa at 90 d. The optimal mix ratio has been found to be 50 kg of cement, 60 kg of fly ash and 120 kg of water (C50F60W120). The related dry density was 2.6 g/cm³, the water content was 6%, and the water-binder ratio was 1.09. [ABSTRACT FROM AUTHOR]