Laboratory Study of the Effect of Degrees of Saturation on Lime Concrete Resistance Due to the Groundwater Level Increment

Abstract

Lime concrete and lime treatment are two attractive techniques for geotechnical engineers in the construction of rail tracks and pavement layers, in slope protection of earth dams, and as a support layer for shallow foundations. The present study investigates the influence of different degrees of saturation upon the unconfined compressive strength (qu) of lime concrete. At first, the characteristics of used materials were determined. Then, the optimum amounts of water and clay soil were determined based on flow table tests and uniaxial compression tests. Specimens with an optimum level of clay, sand, lime, and moisture were prepared. After processing durations of 14, 28, 45, and 60 days in laboratory condition, the specimens were exposed to saturation levels ranging from 0 to 100%. The uniaxial compressive strength tests were then carried out on all specimens. The diagram of strength reduction of lime concrete versus different depths and saturation degrees (Sr) were developed. The results showed that the moisture has a significant effect on decreasing the strength of lime concrete. The specimens that placed in 100% of saturated condition failed completely, and in 20% of saturated condition, the strength value of specimens decreased about 42%. Also, the optimum percentages of clay and water for application in lime concrete with 7% lime, respectively 23 and 24.04% were determined. Based on the results of SEM test it was observed that the specimen was characterized by a rather well-structured matrix since both the filling of a large proportion of the coarse-grain soil voids by clay and the pozzolanic activity of lime led to retain less pore water in the specimen, increasing the uniaxial compressive strength, and consequently resist against swelling and shrinkage of the clay soil.