Specimen size effects for fiber-reinforced silty clay in unconfined compression

A series of laboratory unconfined compression tests were performed on specimens of a compacted silty clay to evaluate how the size of specimens used for strength testing of fiber-reinforced soil affects the measured strength and stress-strain properties. The results of these tests indicate that there is a significant effect of sample size both in terms of the magnitudes of the measured strengths as well as in terms of the variability of the measured strengths. The effects of specimen size were found to be most important for specimens compacted dry of the optimum moisture content. While no clear threshold specimen size was identified, the data indicate that specimens of 70 mm or greater in diameter are likely to produce strengths that are reasonably representative of the "mass" properties of fiber-reinforced soils.