Experimental study of groutability of Super-Micro cement
Based on the similarity theory and the theory of model test, we simulate different opening rock fractures indoors. On account of Super-Micro cement with four different water cement ratios of 0.8, 1.0, 1.5, 2.0 under different water reducer and additive, the experiment is testing the passing rate of Super-Micro cement through the filter with diameters of 0.02mm, 0.05mm, 0.07mm. The test results indicate that the ultimate limit viscosities are 17.1mPa.s, 33.6mPa.s and 624.7mPa.s respectively when the superfine cement passes these three filtrations. After analyzing the influence of grout viscosity on passing rate, that is to say, the bigger the viscosity, the smaller the crack width.
In-Place Treatment of Foundation Soils
The state-of-the-art of seven special methods for the treatment of soils for the support of structures is reviewed. Whereas vibroflotation, compaction piles, blasting and grouting are limited mainly to the treatment of cohesionless soils, electro-osmosis, thermal treatment, and treatment with additives find primary application in the treatment of cohesive soils. Although blasting is usually the fastest and least expensive, compared with vibroflotation and compaction piles, the results are the least certain. Installation of stone column piles by vibroflotation has extended the range of application of this method into cohesive soils. Recently developed chemical grouts are now approaching the ideal in terms of viscosity and control of setting time. Mixed-in-place intrusion grouting appears to be a promising technique for construction of soil-cement piles in place. Additive stabilization of foundation soils for structures is used mainly in connection with grouting and electro-osmosis, with additional application to the treatment of expansive soils to shallow depths.
The principles and applications of grouting
Summary Soils are injected with grouts, the choice of which depends on the nature of the medium to be injected (fissured rock or sand and gravels) and the results desired: imperviousness, consolidation, cavity filling, the jacking-up of buildings. Grouts may be unstable, stable, liquids or foams, and are characterized by their decantation, setting time, viscosity and rigidity. They produce their effect either by impregnation or by “claquage”. For the injection of unstable grouts, the final injection pressures must be limited to a high value, whilst for stable or liquid grouts it is the quantity injected that must be fixed in advance. The applications envisaged relate to: The treatment of galleries, cavity filling, and the jacking up of buildings. Over-strict specifications lead to disappointing results because of the heterogeneity of soils. Controls must relate to results and not to methods.