It is also apparent that the unconfined compressive strength attained by the solidified soil is very much dependent on the w/b ratio, with increased w/b resulting in lower strengths. This is in line with earlier discussions referring to Fig. 3, where q declined with increased w/b. The seeming banding of the q-D plots according to w/b for all soil samples also suggests the dominant influence of w/b on the resulting strength of the solidified soil. In general, the steep rise in q with time was sustained up to 14 days of curing, after which the gradual turn in the plots of Fig. 4 indicates less remarkable strength gain even with prolonged curing. The initial high water content apparently impeded further strength improvement of the soil.
To examine the influence of curing on the solidified strength, q/q28 is plotted against curing time (D) in Fig. 5. For w/b=1, the rate of strength improvement from day 3 to day 28 is higher compared to the subsequent days. This indicates that the cementation process which includes hydration and pozzolanic reactions were most active in the first 4 weeks. There was almost no increment at all in strength after day 28 as shown in the w/b=1 plots in Fig. 5. For w/b=3 and w/b=5, the strength increased steadily from day 3 till day 56, though the strength increment rate in w/b=3 was clearly higher. This could be due to the less excessive water present in the soil-additives mixtures. However, in both cases of w/b=3 and w/b=5, the strength is expected to keep rising with prolonged curing.