I have access to a supply of byproduct hydrate of lime. Could you provide any information as to how this material could be used in road or holding basin construction or in general concrete work? The lime hydrate is a byproduct of acetylene manufacture from calcium carbide. It contains about 77 percent calcium hydroxide, 1.8 percent silica, 1.4 percent aluminum oxide, 0.2 percent sulfur and 20 percent calcium carbonate on the dry basis, but is actually about 65 percent total solids and 35 percent water.
The material doesn't seem promising. It is true that lime slurry can be used for soil stabilization. It is also true that "carbide lime" from acetylene manufacture can be said to have some potential value for this purpose. But because this product tends to be highly variable in chemical composition it is likely to be unreliable. Sometimes fresh carbide lime contains almost 90 percent calcium hydroxide but this slowly converts to calcium carbonate on standing, as your sample analysis shows that yours is doing, thereby diminishing its soil-stabilizing potential. Consequently the composition of your source material is likely to be fairly unpredictable. You could use such lime for soil stabilization by basing your proportions on the lowest calcium hydroxide content you ever receive, but this seems to promise more adjustments and trouble than it is worth. Although dry calcium hydroxide can also be used for the purpose of drying up mud, the wet carbide lime would not be at all useful for this purpose. Use of carbide lime in mortar or concrete work would appear to be bad practice without elaborate control. CONCRETE CONSTRUCTION has published three articles on stabilizing soil or drying up mud: "Lime Stabilizes Poor Soils," May 1967, page 163 "Stabilizing Soils with Lime," October 1968, page 372 "Eliminating Mud the Curse of Construction Jobs," May 1974, page 258 Further information is available from the National Lime Association, 5010 Wisconsin Avenue, N.W., Washington, D.C. 20016; phone 202-966-3418.