Effects of Enzyme and Microbially Induced Carbonate Precipitation Treatments on the Response of Axially Loaded Pervious Concrete Piles

EICP (enzyme induced carbonate precipitation) and MICP (microbially induced carbonate precipitation) treatments were applied through pervious concrete model piles to cement soil around the piles and enhance soil-pile interaction and pile capacity. The behaviors of the pervious concrete piles treated by EICP and MICP when subjected to axial compression loading were compared with each other and with an untreated pervious concrete pile. These tests were performed on 1/10th-scale model piles in the soil-structure interaction (SSI) testing facility at Lehigh University. The piles and surrounding soil were instrumented with strain gauges, bender elements, in-soil null pressure sensors, and a tactile pressure sheet. The responses of the pervious concrete piles and surrounding soil were compared through analysis of shear wave (S-wave) velocities in the treated and untreated soil zones, load transfer along the piles at the ultimate load condition, soil moisture content, calcium carbonate (CaCO3) content and ammonium (NH4+) concentration in soil, and the characteristics of the precipitated CaCO3 crystals along the soil-pile interface. In addition, comparisons with consolidated drained (CD) triaxial test results were made among sand without treatment and with EICP and MICP treatments. The results presented in this paper demonstrated that both EICP and MICP treatments can create a cemented soil zone surrounding the pervious concrete pile and improve the pile capacity and load transfer under compression loading.