L.H. Eilers, Dowell Division of Dow Chemical
Most light weight systems are produced by increasing the amount of water used with each sack of cement. To produce a uniform slurry with this additional water: pozzolans, clays or silicates may be added or fine grinding of the cement composition may be used. These systems, using water as the light weight ingredient have similar ultimate strengths and permeabilities for similar densities. Early strength development as well as ultimate strength and permeability depend on the temperature to which the cement is subjected. Cements in which the density is reduced by using light weight particles instead of water have somewhat different properties. Those using light weight hollow bubbles produce high early strength and improved ultimate strength at an increased slurry cost. Care must be taken that hydrostatic pressure does not crush the bubbles.