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 show marginally better performance for lime with respect to both immediate and time effects of modification. This is attributable to the apparently higher lime—clay ratios of the soil—lime mixes. This better modification by lime over that of cement seems to extent to low clay-content soils, an earlier hypothesis that lime is more effective than cement for modification of soils containing appreciable clay contents. Also, as a result of the better modification by lime, it is hypothesised that cement hydration products other than lime do not play any significant role in cement modification. Other aspects of the results suggest that the pozzolanic reaction in soil—cement seems to commence at about 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. The implication of this for practice, at least in areas where funding is usually a problem like in developing countries, is that it might be more economical in terms of materialsʹ cost to delay further site works (after mixing) for about two hours than to use more cement to achieve a modification result comparable with that of lime.