Fundamental properties of cement-asphalt and cement-bentonite

Cement asphalt (CA) and cement bentonite (CB) mixtures have been developed as fill materials for underground construction. Laboratory tests were carried out and the test results indicate that: (1) The coefficient of permeability tends to decrease with the addition of asphalt or bentonite,and the values are below 10(-7) cm/s. (2) The compressive strength of CB depends on WIG, and is unaffected by the bentonite content. In the case of CA, however, apart from the effect of WIG, unit asphalt content is also an important factor affecting the compressive strength. (3) The modulus of elasticity of CA and CB can be estimated by an equation that relates it to compressive strength, unit cement and unit aggregate ratio. (4) The ultimate drying shrinkage strain is determined primarily by the unit water content. (5) Ultimate creep strain increases in proportion to unit cement content and in inverse proportion to unit aggregate content. Equations for estimating the shrinkage strain and creep strain are also presented in this paper.