Design of a Chemical Grout to Stabilize Poor Subgrade Soil

Abstract

Mostly the damaged road conditions indicates the poor subgrade soil conditions, because after every monsoon there are minor to major potholes in the road as well as many other damages like rutting and cracking. While repairing these damage and make it serviceable often the traffic is to be diverted therefore in this study a quick method of grouting the subgrade for improving its bearing capacity is proposed which would be relatively faster as well as can be done without disturbing traffic for longer duration and also without excavation of the existing road. For this, the laboratory investigations would be carried out for the design of the grout mix and proper method, grouting pressure etc will be calculated. In this study an attempt is made to design a chemical grout with which material sodium silicate and sodium hydroxide. Firstly, all the index properties and engineering properties of the virgin soil is tested. Secondly, the grout is designed by changing the molarity and concentration of the sodium silicate and sodium hydroxide. Various tests are performed like viscosity, gel time and strength. Lastly, the finalized grout is used to grout the soil which was expected to behave as poor subgrade soil in the field. For this, the black-cotton soil was poorly compacted at 50% of its MDD and the grout was proposed to be injected from a test setup designed in house lab. With pressure of 70 MPa. After the grouting the soil sample was retrieve for UCS and the failed samples of UCS were pulverized to check the plasticity characteristics. The results revealed that the proposed grout is working fine and UCS strength of poorly compacted soil is increased by 18.06%.