DBE® esters - Soil Stabilization
Chemical grouting is the practice of injecting a solution into soil to reinforce and stabilize soils and/or increase their load carrying capabilities. This is why grouting is often used as a construction aid. Sodium silicate and a hardener (based on DBE® esters) form such a grouting system. This reaction is analogous to the formation of natural sandstone, which is formed by gluing together loose sand with silicate.
DBE® esters are chemical components to use with aqueous sodium silicate grouts by injecting into the ground through permeation techniques to stabilize medium to fine sandy soils. Reactions of sodium silicate solutions with acids is analogous to the formation of natural sandstone. The system bonds soil together to make a firm medium which the construction teams can use for subway construction or projects requiring large excavation adjacent to existing structures like shafts, and tunnels. It is a proven technique used to provide increased strength, stiffness and reduced permeability in predominantly granular soils. DBE® esters are readily biodegradable and provide an advantage over other soil stabilization methods.
The DBE® esters and aqueous sodium silicate are injected into the soil and undergo a chemical reaction in which the sodium silicate and the water in the aqueous sodium silicate solution react in an equilibrium limited reaction to give the sodium hydroxide and silica. The DBE® esters undergo a base (NaOH) catalyzed hydrolysis yielding the respective dicarboxylate anions (adipate, glutarate, and succinate) and methanol. The sodium hydroxide (NaOH) is depleted by reaction with DBE® esters during the formation of SiO2. Silica precipitates out of the reaction as a uniform gel throughout the area stabilizing the soil. Approximately 3% of DBE® esters are injected for every 1 cubic meter of soil.
Advantages of DBE® esters as a hardener:
- Allows for better control of gel times and greater penetration into soil
- Water solubility of hardener
- DBE® esters are readily biodegradable
- DBE® esters have a low vapor pressure
- Easy to process and handle
