A COMPARATIVE-EVALUATION OF CEMENT AND LIME MODIFICATION OF LATERITE

A report on an investigation conducted to compare the performances of lime and cement as modifiers for laterite is presented. The comparison encompassed immediate and time effects of modification. The results s how marginally better performance for lime with respect to both immedi ate and time effects of modification. This is attributable to the appa rently higher lime-clay ratios of the soil-lime mixes. This better mod ification by lime over that of cement seems to extent to low clay-cont ent soils, an earlier hypothesis that lime is more effective than ceme nt for modification of soils containing appreciable clay contents. Als o, as a result of the better modification by lime, it is hypothesised that cement hydration products other than lime do not play any signifi cant role in cement modification. Other aspects of the results suggest that the pozzolanic reaction in soil-cement seems to commence at abou t one hour after mixing, but does not seem to make any contribution to soil modification. Also, the highly reactive lime produced in cement hydration becomes more effective with time than with cement content. T he implication of this for practice, at least in areas where funding i s usually a problem like in developing countries, is that it might be more economical in terms of materials' cost to delay further site work s (after mixing) for about two hours than to use more cement to achiev e a modification result comparable with that of lime.