EFFICACY OF SODIUM CARBONATE AND CALCIUM CARBONATE IN STABILIZING A BLACK COTTON SOIL
The problem of damage to structures in expansive soils is world wide. These soils are very often referred as black cotton soils. The properties of black cotton soil may be improved to make the soil suitable for construction purposes. There are several techniques to improve the soil properties like sand cushions, CNS layer techniques, sand columns, stone columns, vibration techniques and by adding chemicals etc. Among these, chemical stabilizing is more expensive than other types of stabilization methods. But the main advantage of it is that setting time and curing time can be controlled. The efficacy of sodium carbonate and calcium carbonate is stabilizing a black cotton soil is presented in this paper. The efficacy of calcium carbonate is much better than sodium carbonate from strength and stability point of view.
Carbonates and cementation of glacially derived cohesive soils in New York State and southern Ontario
Cet article presente des resultats se rapportant a la teneur en carbonate de silts et d'argiles naturels en fonction de la profondeur, de l'emplacement geographique et de l'origine geologique. On etudie aussi l'influence de cette teneur en carbonate sur le comportement geotechnique. L'effet sur la pression de preconsolidation apparente est illustre en detail pour l'un des sites etudies. La repartition des carbonates a l'interieur des varves d'un depot glacio-lacustre est egalement presentee pour demontrer la variabilite potentielle de la cimentation naturelle des sols. Les donnees en provenance de quinze sites etayent les relations proposees entre teneur en carbonate et pression de preconsolidation apparente.
Effect of Storage and Reconsolidation on the Properties of Champlain Clays
A testing program has been made on samples of sensitive cemented clays at different times after sampling. When comparing results of unconfined compression tests performed on the field immediately after sampling or in the laboratory the following week, it is observed that there is a decrease in the measured strength which may be attributed to water migration; however, this effect was minimized or eliminated completely by keeping the samples in the tubes or by trimming the samples immediately after sampling. The reconsolidation of the samples to the in situ stresses restored an appreciable part of the strength lost by sampling disturbance; this effect is negligible in the case of good quality samples. Tests made on block samples which had been stored for many years in a humid room have shown a decrease in the shearing of the clay, but the preconsolidation pressure has not been affected.