The aim of this experimental study was to investigate the penetrability of ultrafine Portland cement suspensions with or without additives into sand specimens and the strength and permeability of grouted sand samples. It was shown that ultrafine Portland cement grouts with dispersive agent could be used to treat not only medium to fine sand but also 100% fine sand where chemical grouts can only penetrate The basic rheological properties of ultrafine Portland cement suspensions with or without additives were studied. The penetration performance of suspensions into various graded medium to fine sand specimens prepared at different relative densities was examined. The unconfined compressive strength and the permeability characteristics of sand specimens permeated with ultrafine Portland cement suspensions with or without additives were searched at different time intervals.

This research focused on the strength characteristics of superfine cement–grouted sand with various gradations and relative densities. At first, grout properties of superfine cement suspensions were studied. The sedimentation and the setting time increased but the viscosity decreased as the water–cement (W/C) ratio increased. Additionally, the groutability of superfine cement suspensions with different W/C ratios into various graded sand specimens having different relative densities was tried. The groutability of suspensions especially into the fine sand specimens was successful with certain W/C ratios and increased as the W/C ratio increased but decreased as the relative density increased. Grouted sand samples remained in tanks filled with water at a temperature of 20°C until testing time and subjected to unconfined compressive strength (UCS) tests at different time intervals. The UCS of grouted sand specimens decreased as the W/C ratio increased, but it increased as the relative density increase...

Effectiveness of Microfine Portland Cement Grouting on the Strength and Permeability of Medium to Fine Sands

A new chemical grouting formed by sodium silicate–boric acid mixtures was introduced. Initially, suitable sodium silicate and boric acid contents in the grout mixtures were studied. Gel time, initial viscosity, and syneresis properties of adopted grouts were determined. Strength and permeability of grouted sand specimens having different gradation, relative density, curing time, and condition were investigated. Gel time decreased but viscosity increased as the sodium silicate and boric acid contents increased. Syneresis of grouts increased with the increase in sodium silicate and boric acid contents. As the silicate content of the grout solutions increased, the unconfined compressive strengths of the wet-cured and air-dried specimens increased, but decreased with time as a result of syneresis. The permeability of the wet-cured sand specimens decreased by two to three orders of magnitude after grouting; it increased with increasing silicate content but decreased with increasing in boric acid content.

In this experimental study, the effect of silica fume on the grouting performance of superfine cement and the engineering properties of grouted sand was examined. The experiments were first launched with rheological property determination tests. Bleeding, setting time, and viscosity tests were performed on superfine-cement suspensions with or without silica fume in different water/cement (W/C) ratios. Then, groutability tests were performed on fine to medium sand mixtures prepared in various gradations. Finally, unconfined compression strength (UCS) and falling-head permeability tests were performed on the samples that were successful in the grout test at different time intervals. With the addition of silica fume to superfine cement, the initial and final setting times as well as viscosity values increased, whereas bleeding values decreased. With the addition of silica fume to the superfine cement, the groutability slightly decreased, but the grouting pressure values increased. With the addition of silica fume to superfine cement, UCS values increased, although the permeability values decreased. Sand samples grouted with a superfine-cement suspension with silica fume additive gained strength later than sand samples grouted with superfine-cement suspensions with no additive. Experimental studies have shown that the addition of silica fume to superfine cement improves the engineering properties of the grouted sands.

In this experimental study, the effect of sodium silicate (SS) added into an ultrafine-cement-suspension injection on the strength and permeability properties of grouted sand samples was investigated. The experiment started with a test for identifying the bleeding and viscosity values and setting times. This was followed by injecting sand samples prepared in different gradations with ultrafine cement (UC) with and without SS additive. In the experiments, 1.0, 1.5, 2.0, and 2.5 were used as the water:cement ratios, and 1%, 3%, and 5% were used as the SS additive ratios. Unconfined compression tests were performed on the sand specimens that were successful in the injection tests on days 3, 7, 14, 28, 56, and 90; and permeability tests were performed on days 7, 28, 56, and 90. While viscosity values increased with the addition of SS into the UC, bleeding values and setting times decreased. Injectability slightly decreased with the addition of SS into the UC. The addition of SS into the UC-suspension injection increased the unconfined compressive strength. Injected samples gained strength faster with the addition of SS into the UC. Adding sodium silicate into the UC-suspension injection reduced permeability values. In the experimental study, it was observed that the addition of SS additive into the UC improved the permeability and strength properties of sand samples after injection.