Feasibility of Using Liquid Polymer to Grout Soil with High Fine Contents

For a long time, grouting predominantly uses cementitious materials to fill voids and/or create bonding between soil particles, which in general have been performing well in highly permeable soil, such as sands and gravels. However, for soil with low permeability, for example, fine grain soil or coarse grain soil with high fine contents, cementitious materials typically are not applicable due to low flowability. Water-activated polymer (WAP) may be an excellent alternative to cementitious material to expand the groutable spectrum of soils. Among many types of WAPs, this study uses a polymer precursor that is liquid and has a viscosity as low as 25 centipoise, which means it is as flowable as low fat milk. In addition, WAP is made of macro-molecules, and the size of molecules is in the scale of nanometer, which makes them much smaller than cement particles. Therefore, using WAP to replace traditional cementitious materials as grouting materials has great potential to expand the application to fine-grain soils. This study focuses on studying the viscosity of WAP during its curing process as well as its penetration capacity for different pore sizes. The viscosity was measured by a viscometer under a controlled-temperature environment, while the penetration was measured by micro-filteration membrane with sub-micron pores. The results indicate that during the curing process, the viscosity experienced three phases of change: first increase and then decrease and finally increase again. As to penetration, the WAP can easily penetrate through micro-membranes with a pore size of 0.22 μm. Based on the test results, a preliminary estimation of the groutability was performed based on the existing pore size model. It showed that it can be used in many fine-grain soils, which are considered ungroutable for cementitious materials.