Murat Mollamahmutoğlu

Engineering Properties of Medium-to-Fine Sands Injected with Microfine Cement Grout

This article investigates the penetrability of microfine cement suspensions prepared with Rheocem 900 with and without superplasticizer additive into various graded fine-to-medium sands into which chemical grout permeation is only possible. Initially, the basic rheological properties such as viscosity, setting time, and stability of microfine cement suspensions are studied. In addition, penetration performance of the suspensions into various graded fine to medium sand specimens under different grouting pressures is examined. Finally, the strength and permeability characteristics of various graded fine-to-medium sand specimens permeated with microfine cement suspensions are studied. It is found that a superplasticizer additive greatly increases the grouting performance of microfine cement and reduces the grouting pressure. Moreover, it is seen that the unconfined compressive strengths of sand specimens permeated with a cement grout without additive are slightly less than those of sand specimens permeated with cement grout and superplasticizer additive. Furthermore, permeability tests on specimens permeated with cement grouts with or without a superplasticizer reveals that all specimens are impermeable (k < 1 × 10−7 m/s).

Characterization of Liquefaction Susceptibility of Sands by Means of Extreme Void Ratios and/or Void Ratio Range

The liquefaction susceptibility of various graded fine to medium saturated sands are evaluated by stress controlled cyclic triaxial laboratory tests. Cyclic triaxial tests are performed on reconstituted specimens having global relative density of 60%. In all cyclic triaxial tests, loading pattern is selected as a sinusoidal wave form with 1.0 Hz frequency and effective consolidation pressure is chosen as 100 kPa. Liquefaction resistance is defined as the required cyclic stress ratio causing initial liquefaction in 10 cycles during the cyclic triaxial test. The results are used to draw conclusions on the effect of the extreme void ratios and void ratio range on the liquefaction resistance of various graded sands.

Liquefaction-related building damage in Adapazari during the Turkey earthquake of August 17, 1999

The goal of this paper is to present especially the source and the type of liquefaction-related failures of those buildings which satisfied the structural codes of buildings and practices but experienced settlement, tilting and overturning in Adapazari during the Turkey earthquake of August 17, 1999. In this context, the Adapazari region is first evaluated in terms of geological setting, tectonics, seismicity and liquefaction susceptibility based on in situ and laboratory test data. In addition, the number of stories, types of buildings and their related failures have been mapped accordingly. Furthermore, laboratory model tests are conducted to enforce and/or confirm the type of buildings failures with particular reference to their geometrical shape and the number of stories assuming that the models representing buildings satisfy the structural codes of buildings and practices.

Treatment of Medium- to Coarse-Grained Sands by Fine-Grained Portland Cement (FGPC) as an Alternative Grouting Material to Silicate-Ester Grouts

Due to the inability of Ordinary Portland Cement (OPC) grouts to permeate such soil formations as fine- to medium-grained and/or medium- to coarse-grained sands and the problems associated with permanence and toxicity of chemical grouts, advanced studies have shown that fine grained portland cement (FGPC) based grouts may be used to overcome the difficulties mentioned above and hence, an opening in the market has appeared for the manufacture of very fine-grained cements. In this context, comparative laboratory studies were conducted on commercially available OPC, FGPC, and silicate-ester grouts, and it has been found that FGPC has better flow properties and bleed characteristics than OPC. Furthermore, its permeation into medium- to coarse-grained sand is as effective as silicate-ester grout and the strength of the sand gained by the injection of FGPC is higher than that of silicate-ester grouted sand.

UCS Properties of Superfine Cement–Grouted Sand

AbstractThis 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...

Performance of Novel Chemical Grout in Treating Sands

AbstractA 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 tim...

Syneresis dependent shear strength parameters of sodium silicate grouted sands

The influence of syneresis on the shear strength parameters of both sodium silicate-formamide and sodium silicate-glyoxal grouted sands was investigated under wet-cured as well as air-dried conditions. Syneresis of sodium silicate-formamide and sodium silicate-glyoxal grout gels increased with the increase of sodium silicate content up to a certain point. After which, as the silicate content of both grout gels increased, their syneresis decreased. In general, syneresis of sodium silicate-glyoxal grout gels was higher than those of sodium silicate-formamide grout gels. Syneresis of sands injected by the above-mentioned grouts was also observed and found to be less compared to the related grout gels. Triaxial tests were run on both wet-cured and air-dried sand specimens at different time intervals to determine the effect of syneresis on the internal friction angle and cohesion intercept of grouted sands. Due to syneresis, the shear strength parameters of wet-cured sand specimens decreased with time to some extent and then ceased to have an effect. In contrast, the shear strength parameters of air-dried sand specimens increased with time up to a certain point, even though they underwent syneresis, and then became stable.

Syneresis effect on the permeability of chemically grouted sand

The aim of this research was to investigate the permeability of sodium silicate grouted sand specimens having various gradations and relative densities. Initially, rheological properties of sodium silicate grouts were studied. The gel time decreased as the sodium silicate content increased. Viscosities of sodium silicate grouts increased as the silicate content increased. Syneresis of sodium silicate grout gels increased with the increase of silicate content up to a point and then started decreasing sharply. The penetrability of chemical grouts with different sodium silicate contents into various graded sand specimens prepared at different relative densities was highly successful. Grouted sand samples were kept in humid conditions at a temperature of 20°C until testing time and were subjected to permeability tests at different time intervals. In general, sodium silicate grouting reduced the permeability of various graded sand specimens. The permeability of grouted sand specimens slightly increased with time as a result of syneresis.