Enhancing the Axial Compression Response of Pervious Concrete Ground Improvement Piles Using Biogrouting

This paper presents an innovative grouted ground improvement pile alternative (biogrouted pervious concrete pile). Biogrouting is a potential ground improvement technique that utilizes soil bacteria to induce calcium carbonate (CaCO3) precipitation to cement soil particles. The most commonly investigated biogrouting method is microbial-induced carbonate precipitation (MICP). Previous large-scale applications of MICP have encountered practical difficulties including bioclogging, which results in a limited zone of cemented soil around injection points and heterogeneous distribution of CaCO3. The research presented in this paper focuses on evaluating the feasibility of MICP biogrouting of a limited soil zone surrounding permeable piles to improve their responses when subjected to axial compression loading. To investigate this, two instrumented pervious concrete piles with diameters of 76 mm and lengths of 1.07 m with and without MICP biogrouting were subjected to compression loading at the Soil-Structure Interaction (SSI) facility at Lehigh University, Bethlehem, Pennsylvania. The pervious concrete pile serves as an injection point during the MICP biogrouting. The mechanical responses of the pile and surrounding soil were analyzed, along with shear wave (S-wave) velocity, moisture content, and CaCO3 and ammonium contents of the surrounding soil. The results presented in this paper demonstrated that the limited MICP-improved zone around pervious concrete piles improved the load-displacement response, load transfer, and pile capacity under compression loading.