Soil Stabilisation Essay

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USING LIME FOR SOIL STABILIZATION AND MODIFICATION A PROVEN SOLUTION! LIME MEETS THE CONSTRUCTION CHALLENGE: Lime is an unparalleled aid in the modification and stabilization of soil beneath road and similar construction projects. Using lime can substantially increase the stability, impermeability, and load-bearing capacity of the subgrade. And lime is a proven solution--witness the more than one million metric tons of lime used annually in the U.S. for soil modification and stabilization. LIME AND SOIL MODIFICATION: Lime is an excellent choice for short-term modification of soil properties. Lime can modify almost all fine-grained soils, but the most dramatic improvement occurs in clay soils of moderate to high plasticity. Modification occurs because calcium cations supplied by the hydrated lime replace the cations normally present on the surface of the clay mineral, promoted by the high pH environment of the lime-water system. Thus, the clay surface mineralogy is altered, producing the following benefits: • • • • • Plasticity reduction Reduction in moisture-holding capacity (drying) Swell reduction Improved stability The ability to construct a solid working platform These benefits expedite construction and save time and money. (For more information, see NLA’s factsheet on using lime to dry up mud, at http://www.lime.org/mud.pdf.) LIME AND SOIL STABILIZATION: Soil stabilization occurs when lime is added to a reactive soil to generate long-term strength gain through a pozzolanic reaction. This reaction produces stable calcium silicate hydrates and calcium aluminate hydrates as the calcium from the lime reacts with the aluminates and silicates solubilized from the clay. The full-term pozzolanic reaction can continue for a very long period of time, even decades -- as long as enough lime is present and the pH remains high (above 10). As a result, lime treatment can
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