Lime stabilization of clay minerals and soils

This report presents information on the characterization of cementitiously stabilized layers and the properties that influence pavement performance. It also contains recommended performance-related procedures for characterizing these layers and performance-prediction models for incorporation into the mechanistic–empirical pavement analysis methods. Individual chapters highlight pavement distresses of hot-mix asphalt pavements and concrete pavements, laboratory tests and model development, and model calibration. The material contained in the report will be of immediate interest to state materials, pavement, and construction engineers and others involved in the different aspects of pavement design and construction.

Characterization of Cementitiously Stabilized Layers for Use in Pavement Design and Analysis

Clay soil can be stabilised by the addition of a small percentage, by weight, of lime, that is, it enhances many of the engineering properties of the soil. This produces an improved construction material and so the technique has been used for many construction purposes, notably in highway, railroad and airport construction to improve subgrades and sub-bases. Generally the amount of lime needed to modify a clay soil varies from 1 to 3 per cent, whilst that required for cementation varies from 2 to 8 per cent. When lime is added to clay soils, calcium ions are combined initially with or adsorbed by clay minerals which leads to an improvement in soil workability, that is, to an increase in the plastic limit of the clay and generally to a decrease in its liquid limit. The optimum lime additive for maximum increase of the plastic limit of the soil is referred to as the lime fixation point Lime added in excess of the fixation point is utilised in the cementation process and gives rise to an increase in soil strength. The increase in strength has been attributed to the formation of poorly ordered reaction products which surround the clay minerals.

Lime stabilisation of clay soils

An experimental study was conducted to evaluate the suitability of lime for the improvement of weak fly ash ground. In the study, a series of unconfined and confined compression tests were carried ...

Bearing capacity and settlement of weak fly ash ground improved using lime fly ash or stone columns

Laboratory and field testing for utilization of an excavated soil as landfill liner material.

The relation between sample preparation and curing procedures, and the engineering properties of compacted soil-lime mixes was investigated. Four natural Oklahoma soils of different origins were used in this study. The effects of variation of lime content, water content, and curing environment factors were evaluated on the basis of the strength, permeability, and pH of compacted specimens. It was found that the compressive strength increases with increasing lime content. Strength improvement was most conspicuous in the samples compacted at moisture contents above the optimum; the strength of samples compacted at lower moisture content could usually be improved by increasing the availability of water during curing. The soil pH appears to be an important factor controlling the soil strength, but its influence is better regulated by the lime-water ratio than by lime-soil ratio. The permeability of all soils was increased by the addition of lime, but the effect is reduced when water is sprinkled on the compacted lifts prior to curing.

Mohamed M. Aly Sabry

Papers

Engineering Properties of Soil-Lime Mixes