The effect of soaking on the durability of the soil stabilised with different admixture ratios is shown in Fig. 4. For a better understanding and illustration,the strength values of different B/C and B/L ratios at a curing time of 28 day sand an admixture content of 15% are presented in Fig. 6, which shows the stress–strain relationship. The increase in the admixture ratio is as so ciated with a decrease in durability of both admixtures.
This result is most likely related to the decrease in the proportion of solidification agents,cement,or lime,in the soil mixture,which decreases the ability of the stabilised soil gypsum to resist the effect of soaking. In fact,the solidification agent in the stabilised soil gypsum is considered to be the main factor responsible for the
resistance to soaking as well as for the improvement in durability, because gypsum is a soluble material in water. It is clear from this figure that the effect of soaking on the durability is much more pronounced for the early soaking times.For more than 15 days of soaking,the durability improvess lightly in some cases or stays the same. This result is consistent with the results obtained when evaluating the effect of the admixture content on durability. For
admixture ratios of 2:1 and 3:1, the effect of the soaking condition is more negative on the durability index than for samples stabilised with B–L compared with the samples stabilised with B–C. It is related to the fact that the solidification of cement is higher than that of lime so a decrease in the proportion of lime has a significant effect on the durability of the soil mixture. Generally,it is important to report that improvements in the stress–strain relationship increase with an in creasingad mixture content and a decreasing admixture ratio for both admixtures used,as presented in Figs. 5 and 6. These figures show the effect of the admixture content and ratio on the stress–strain relationships for the samples stabilized with the two admixtures of B–C and B–L with out the
soaking condition at the curing time of 28 days. It is obvious from these figures that the B–L admixture has a significant effect on the improvement of the stress–strain relationship compared to the samples stabilized with the B–C admixture.