The research reported here is a continuation of work reported earlier in which it was concluded that the use of expansive cement concrete increased the side resistance of drilled shafts (bored piles) in stiff clay by as much as 50% over that in normal concrete shafts and reduced the settlement by about 50%. The conclusions were based on tests conducted at a concrete age of about 2 months. A year and a half later, the three shafts (one made with normal concrete and two made with expansive concrete) were tested again and the same comparatively better behavior of expansive concrete shafts was observed. The base capacities of all the shafts increased over this period owing to the consolidation of soil caused by residual base stresses following the initial tests. The shafts were later extracted for visual observation and coring. The compression tests on concrete cores obtained from various depths along the shafts indicated that expansive concrete behaves as a sound structural material in the long term. The gains in strength and stiffness of expansive concrete over normal concrete over a period of 2 years were found to be significant. Key words: base bearing capacity, bored pile, cement (expansive), concrete (structural), drilled shaft, expansion, frictional capacity, long-term behavior, settlement.
The effect of expansive concrete on the side resistance of sockets in weak rock
