Compaction Grout Research Articles

Engineering Characteristics at Early Age of Cemented Silica Fume Paste for Peat Compaction Grouting

Introduction Cemented Silica Fume Paste (CSFP) is currently being investigated for compaction grouting material to improve peat ground engineering properties. The CSFP is made in the laboratory using a proportional mixture of silica fume, cement binder, and tap water. The silica fume material is a byproduct of the metal processing industry, which critically requires a better alternative utilization in the near future in order to cut the storage cost and minimize the environmental impact. Aims This paper aims to present preliminary results on the engineering characteristics of CSFP at an early age through a series of rheological and strength tests. A general observation of the physical properties and microstructure of CSFP is also presented. Methods The CSFP specimens with cement binder range from 0% to 30% with the increment of 5% and Water-to-Solid (W/S) ratio ranges from 0.8, 0.9 and 1.0 were prepared and tested. A series of rheology test and Unconfined Compressive Strength (UCS) tests were carried out for the CSFP specimens at an early age. The data were analyzed statistically and mathematical formulation is presented. Results The results indicate that CSFP mixtures behave as pseudoplastic or shear thinning fluid, where the shear stress and viscosity depend highly on the shear rates. The higher the shear rates, the higher the shear stress and the lower the viscosity. Curve fitting showed that the best relationship between shear stress and shear rate is the power law function (Ostwald–de Waele relationship). Statistical parameters, k, n, R2 of the power law functions are reported. There was no good correlation found between the power law function statistical parameters and the cement content. The UCS tests showed that the shear strength increases with the amount of cement content. The actual W/S reduces as the cement content increases, which is attributed to the cement hydration. Conclusion The CSFP mixtures were found to be a pseudoplastic or shear thinning fluid at an early age that provides an advantage during the material injection on the ground. Cemented Silica Fume Paste can be potentially used as compaction grout to improve peat. The current findings provide a better understanding of the CSFP characteristics and to better design CSFP to be injected into peat ground.

An in situ low-pressure grouting application

This study examined the effects of low-pressure grouting on soil properties at a site that is at risk of soil liquefaction. The study was conducted at a 96 m2 site located in Yalova, Turkey, that is considered a first-degree seismic zone. Compaction grout was injected into a silty sand layer at 100 kPa and 150 kPa pressure at three different points at depths of up to 9 m. Standard penetration tests, cone penetration tests and seismic refraction tests were conducted before and after the grouting, to determine the effect of grouting on the soil properties in the field. Grout injection holes were drilled at a spacing of 1·25–3·0 m. Grout injection was observed to be impossible in wells that were spaced closer than 1·50 m, because of the diffusion of grout from primary injections. The injected grout volume was calculated to be 5% of the total soil volume. The results from the tests indicate that the bearing capacity of the soil increased by approximately 50%, and the safety factor with respect to liquefaction increased by a factor of up to 100%.

Field Investigation into Effectiveness of Compaction Grouting

AbstractThe common design approach of compaction grouting for ground improvement works is oversimplified and does not account for the effects of soil properties and grouting variables. The obtained improvements therefore appear inconsistent with the predicted ones. This paper presents the results of a field test conducted at Tokyo International Airport to evaluate the effectiveness of compaction grouting under well-controlled conditions. The test consisted of 87 compaction grout piles injected in three cases of different pile diameters and spacings. The paper also discusses the effects of soil properties, replacement ratio, and injection sequence on the effectiveness that is evaluated in terms of the standard penetration test N-value and cone penetration test tip resistance, and the variation of effectiveness with depth. A new design procedure that accounts for the effects of initial soil properties is introduced. It has been found that the injection sequence has a significant effect on the grouting mecha...

Large Scale Laboratory Testing of Low Mobility Compaction Grouts for Drilled Shaft Tips

Abstract While post grouting of drilled shaft tips is an acknowledged means of mobilizing shaft base resistance at low values of displacement, much uncertainty exists among engineering professionals as to the conditions under which this option may be entertained. The impact of diverse factors such as soil gradation and soil relative density, overburden pressures, and grouting methods utilized needs to be properly understood. This paper details the laboratory test set-up utilized by researchers toward studying the impact of such factors on post grouting and resultant shaft base capacity increase. The focus of this paper is on the different components of the test set-up considered during the design and implementation stage. Several unique aspects dealt with as a part of this study and elaborated on herein include the testing chamber dimensions, method of overburden pressure application, soil deposition technique, grouting methodology employed for the low mobility compaction grout utilized, load testing protocol, and instrumentation. Sample test results included indicate satisfactory load resistance increase through grouting with a low mobility compaction grout. The performance of this set-up during the testing phase indicated applicability for use in large scale laboratory testing of low mobility grouts and drilled shaft foundations.

Compaction Grouting Test Program for Liquefaction Control

Following the 1989 Loma Prieta earthquake a detailed analysis of liquefaction risk was carried out for an industrial site near the Pajaro River at Watsonville, Calif. A ground improvement project, by grouting, was proposed to prevent lateral spreading and a compaction grout test program was undertaken to validate and refine the project design. In phase 1 of the test program the grout hole spacing was 2.5 and 1.8 m (8 and 6 ft). In phase 2, a closer hole spacing was used, 1.5 and 1.2 m (5 and 4 ft.) The test program employed cone penetration tests and standard penetration tests measurements for evaluation before and after each phase. The results showed the relationship of ground improvement versus grout hole spacing, grout take, and grout pressure. The test program showed that a zone of susceptible soils at the site could be effectively improved to increase their strength and resistance to liquefaction and thus prevent lateral spreading during severe earthquakes.