Permeability characteristics of lime treaded soils

Abstract

Thc effects of lime content on the permcability of lime- trcated soils were investigated. Three soils, namely, a fine sand, a rclatively coarse sand and a clay were collected from diffcrent areas of Bangladesh for thesc purposes. After collecting the soil-mass from the field, they were dried and cleaned. The clay was made powdered by using a grinding machine. Lime, in the predetermined proportion, was mixed thoroughly with the soil. Water was mixed with it for reaction to occur and then a sufficient timc was allowed to complete hydration. Afterwards, the sample was subjected to permeability test. Permeability of sandy soils was determined by performing falling head permeability tests on the respective samples, while for clay soil consolidation tests were performed. Falling head penneability test was performed using a 62.5mm dia and 100.Omm high cylindrical sample enclosed in a perplex permeameter. On the other hand, consolidation test on lime treated clay was performed on 62.5 mm dia and 25.4 mm thick cylindrical sample. In the research scheme, limc content was varied up to 5% and the rc,action timc was varied up to 14 days, i.e., aftcr mixing a particular soil with a dcfinite percent of lime and sufficient watcr, the mixture was allowed to complete hydration at room temperature for 4, 5, 8 and 14 days before testing. Test results show that regarding to permeability, cohesive soil was more sensitive than cohcsion-Iess soils. Permeability incrcased in case of fine-grained soils (i.c., both the finc sand and clay) with the increase of limc content, but it decreased for relatively coarse-grained soil. Void ratio of lime treated soil was influenced by the addition of lime. For soils with having substantial amount of fines (say, a fine sand and the clay), it was observed that void ratio increased, while for the sand having less fines exhibited a decrease in void ratio with lime content. The permeability characteristic also changed accordingly. Aging had no affect on the permeability and void ratio of untreated soils, but after a certain period of time, the lime treated sand exhibited more or- less stable perneability characteristics during a span of about 30 hrs.