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.
Experimental study on bond behavior between high-strength grout and deformed steel bars
Abstract Engineers use high-strength grout to connect precast concrete members for its low shrinkage and good fluidity. This paper designed 87 central pull-out specimens using the control variable method to investigate the influence of factors on the rebar-grout bond property such as compressive strength, steel grade, bar diameter, transverse stirrups, and bond length. The test result showed that improving grout compressive strength (85.8 MPa–122.7 MPa) cannot improve the bond strength, which was different from the previous conclusions of concrete pull-out tests. Simplified formulas were presented for calculating the characteristic values of bond strength, residual strength, peak slip, and relative slip of load-holding platform based on parameter analysis. Then, a constitutive model was proposed to predict the full-range bond stress-slip curve of high-strength grout and steel bar specimens from bearing to failure. Finally, FEA models were established to evaluate the applicability and accuracy of the constitutive model.