In construction project, knowing the type and characteristics of the soil is a very
important thing. Not all soil have a good performance to support the structure
above it. If the construction building is constructed above the weak soil, it is risky
and susceptible to collapse because such soil has a differential settlements due to
its poor shear strength and high compressibility. Therefore, an effort to change the
soil characteristics to increase its engineering performance is highly required.
Experiments to improve the strength of volcanic sand by the polyurethane-resin
(PU) as additive material conducted in this research. The objectives of this
research is to investigate the effects of adding polyurethane-resin for soil shear
strength improvement. Specimens were prepared by adding different amount of
polyurethane-resin (2%,4%,6%, and 8%) to volcanic sand. The shear strength of
specimens determined with direct shear test and compared to each other with the
different curing time condition (0 and 7 days) to get the effect of polyurethaneresin
on volcanic sand. The results of this research indicated that the addition of
polyurethane-resin improve the shear strength of sample. The optimum level of
shear strength on sand + 8% PU at 7 days curing time with the average shear
stress value is 0.131 kg/cm2 , it is increase 14.91% compared with the original soil
shear strength. However, polyurethane-resin enhanced the strength of samples
after 7 days of curing time, but the strength of 0 day curing time is less than the
original soil without additive material.