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Öğe Cement Type Effect on Improvement of Clayey Soil Properties(Amer Concrete Inst, 2018) Mollamahmutoglu, Murat; Avcı, EyübhanIn this paper, some geotechnical properties of low-plasticity clay blended with calcium aluminate cement (CAC) at different contents were investigated and compared with those of sulfate-resistant cement (SRC)-blended law plasticity clay. As the liquid limits of CAC and SRC-blended low-plasticity clay decreased, their plastic limits increased. Additionally, the liquid limit and the plastic limit of CAC-blended low-plasticity clay were found to be lower than those of SRC-blended low-plasticity clay. The optimum moisture content and maximum dry density of low-plasticity clay were increased by both CAC and SRC agents. Moreover, the optimum moisture content and maximum dry density values of CAC-blended law plasticity clay were higher than those of SRC-blended low-plasticity clay. The shear strength of low-plasticity clay was also increased with the CAC and SRC additives. The internal friction angles of CAC-blended low-plasticity clay were higher than those of SRC-improved law plasticity clay under both the wet-cured and air-dried conditions. The cohesion intetrepts of CAC-improved low-plasticity clay under both the wet-cured and air-dried conditions were lower than those of SRC-improved low-plasticity clay. The compressibility and swell characteristics of law plasticity clay were considerably reduced with both CAC and SRC admixtures. However, the swell and compressibility of CAC-blended low-plasticity clay were lower than those of SRC-blended law plasticity clay. Generally; the CAC agent was more effective than the SRC agent in the improvement of aformentioned low-plasticity clay properties.Öğe Clinker Efficiency in the Treatment of Low-Plasticity Clay(Asce-Amer Soc Civil Engineers, 2018) Avcı, Eyübhan; Mollamahmutoglu, MuratThis paper presented some geotechnical characteristics of low plasticity clay (LPC) treated with clinker in comparison with those of ordinary portland cement (OPC) treated LPC. The chosen percentages of both additives were 10, 12, and 14% for the stabilization of LPC. While the liquid limits of clinker and OPC treated LPC decreased, their plastic limits increased. The liquid limit (LL) and the plastic limit (PL) of clinker treated LPC were found to be lower than those of OPC treated LPC. The optimum moisture content (OMC) and maximum dry density (MDD) of LPC were increased by both clinker and OPC treatment. In addition, the OMC values of clinker treated LPC were higher than those of OPC treated LPC. However, the MDD values of clinker and OPC treated LPC were almost the same. The shear strength of LPC was also increased with the clinker and OPC treatments under both the wet-cured and air-dried conditions. The compressibility and swell characteristics of LPC were considerably reduced by both clinker and OPC treatments. Nevertheless, the swell and compressibility of clinker treated LPC were lower than those of OPC treated LPC. It was found that the clinker was more effective than that of OPC in the treatment of LPC. (c) 2018 American Society of Civil Engineers.Öğe Dynamic compaction experience in alluvial soils of Carsamba (Turkey)(Maejo Univ, 2018) Mollamahmutoglu, Murat; Avcı, EyübhanA case study using dynamic compaction to improve alluvial soils of a collective housing project area in Carsamba, Turkey, is presented. In-situ field pilot tests were employed to determine the optimum number of tamping, the grid spacing, the effective depth of improvement and the degree of densification of compacted soil. Optimal compaction conditions were found to be: grid spacing - 6.0 m and tamping number under a weight of 15-ton mass falling freely from a height of 18 m - 6.0. Based on the measurements of Standard Penetration Test Numbers (SPT-N) values before and after the dynamic compaction, it was found that SPT-N values were increased by more than 100% near ground surface (including the effect of filling and levelling) at some points, and the depth of ground improvement was experimentally determined to be 9.5 m. Dynamic compaction had an unfavourable effect on thin clay layers of about 0.5 m thick found at varying depths in two different locations since SPT-N values for the clay layers were reduced by as much as 50% after dynamic compaction. However, soil layers beneath the clay layers could be improved to some extent.Öğe Effects of Particle Gradation, Relative Density and Curing on the Strength of Silicate Grouted Sand(Springer, 2020) Mollamahmutoglu, Murat; Avcı, EyübhanThis research paper presented the influence of variables such as sand gradation, relative density, curing time and condition and sodium silicate content on the strength characteristics of sodium silicate-formamide injected sand. To start with, the viscosity, gel time, and syneresis of sodium silicate-formamide grouts were studied. With the increase of sodium silicate content in the grout mix, the setting time of sodium silicate-formamide solutions decreased but the viscosity increased. Additionally, an increase in silicate content increased the amount of syneresis of grouts up to a specific point. The grouts with various silicate contents successfully penetrated the sand specimens with different grain size distributions and relative densities. The wet-cured and the air-dried samples were subjected to unconfined compressive (UC) and undrained-unconsolidated (UU) triaxial tests at various time intervals. The UC strengths of wet-cured as well as the air-dried specimens varied from 0.11 to 0.80 MPa and from 0.48 to 2.52 MPa respectively at the end of the 150th day. Moreover, as the internal friction angles of wet-cured and air-dried specimens ranged from 36 degrees to 43 degrees and from 41 degrees to 50 degrees the cohesion intercepts of wet-cured and air-dried specimens varied from 40.78 to 161.68 kPa and from 85.84 to 348.62 kPa respectively at the end of 150th day. As the silicate content of grouts increased, UC and UU strengths of air-dried and wet-cured samples increased. The UC and UU strengths of injected sand specimens under wet-cured condition reduced with time owing to syneresis. However, the UC and UU strengths of grouted specimens under air-dried condition increased with time. Though the strength of grouted sand samples was slightly increased with the increase of relative density, it was found to be highly variable with the grain size distribution.Öğe Engineering Properties of Slag-Based Superfine Cement-Stabilized Clayey Soil(Amer Concrete Inst, 2018) Mollamahmutoglu, Murat; Avcı, EyübhanThe aim of this research was to investigate such geotechnical properties as consistency limits, unconfined compressive strength (UCS), permeability, swelling potential, and the compressibility of slag-based, superfine cement (SSC)-stabilized, high-plasticity clayey soil. LICS ofhigh-plasticity clayey soil was increased by SSC stabilization under both wet-cured and air-dried conditions. UCS values of SSC stabilized specimens under both conditions increased with time. Additionally, UCS values of SSC-stabilized specimens under air-dried condition were higher than those of SSC- stabilized specimens under wet-cured condition. The permeability of high-plasticity clayey soil was reduced by the SSC stabilization, and the permeability of SSC-stabilized soil decreased with time. The swelling potential and the compressibility of high-plasticity clayey soil were also reduced by SSC stabilization.Öğe Evaluation of the Validity of Groutability Prediction Formulas by Means of Superfine Cement Grouts(Springer, 2019) Mollamahmutoglu, Murat; Avcı, EyübhanExtensive laboratory grouting tests were conducted using ultrafine cement suspensions to evaluate the validity and reliability of groutability prediction formulas proposed by several researchers for the cement based grouts of soils. Initially, such basic rheological properties as setting time, viscosity and stability of ultrafine cement suspensions with or without dispersive agent were studied. Next, the penetration performance of suspensions into various graded medium to fine sand specimens prepared at different relative densities was investigated. Finally, the grouting test results were compared with those obtained from groutability prediction formulas and it was found out that the proposed prediction formulas could not be used as a sole and exclusive criterion to predict the groutability of soils.Öğe Performance of Novel Chemical Grout in Treating Sands(Asce-Amer Soc Civil Engineers, 2017) Mollamahmutoglu, Murat; Avcı, Eyübhan; Tomac, Sercan Kerem; Kose, Dursun AliA 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. (C) 2017 American Society of Civil Engineers.Öğe PROPERTIES OF SUPERPLASTICIZER-AMENDED SUPERFINE CEMENT GROUTED SAND(Serban Solacolu Foundation, 2019) Mollamahmutoglu, Murat; Avcı, EyübhanThe effect of superplasticizer on the grouting performance of superfine cement and the engineering properties of grouted sand were investigated. At first, the bleeding, setting time, and viscosity tests were conducted to determine the theological characteristics of superfine cement grouts with or without superplasticizer at different water-cement ratios. Thereafter, the groutability of superfine cement grouts into various graded sand specimens with or without superplasticizer were tested. Those specimens grouted successfully were then subjected to unconfined compression tests at different time intervals. The addition of superplasticizer to superfine cement grouts increased their bleeding, initial and final setting times but decreased their viscosities. As the unconfined compressive strength (UCS) of superfine cement grouted sand specimens increased with the addition of superplasticizer. It was shown that the engineering properties of superfine cement grouted sand specimens were better improved with the addition of superplasticizer.Öğe Strength and Permeability Characteristics of Superfine Cement and Fine Fly Ash Mixture Grouted Sand(Amer Concrete Inst, 2020) Avcı, Eyübhan; Mollamahmutoglu, MuratThe strength and permeability properties of various graded sand specimens grouted with superfine cement suspensions containing an additive of fine fly ash were experimentally investigated. To start with, such rheological properties as viscosity, bleeding, and setting time of superfine cement and fine fly ash mixture suspensions with various water-cement ratios (w/c) were determined. Then, the injectability tests with the mixtures were conducted on various graded sand samples. Finally, the unconfined compressive strength and the falling head permeability tests were run on the grouted specimens at different time intervals. The setting times and viscosities of superfine cement and fine fly ash mixture suspensions increased, but their bleedings were reduced. The addition of fine fly ash to superfine cement suspensions reduced the groutability of suspensions and hence increased the grouting pressure of sand specimens. The unconfined compressive strength of superfine cement grouted sand samples were increased and their permeabilities were reduced with the addition of fine fly ash. Moreover, the addition of fine fly ash to superfine cement grouts accelerated the grouted specimens' strength gain.Öğe Syneresis dependent shear strength parameters of sodium silicate grouted sands(Geological Soc Publ House, 2019) Avcı, Eyübhan; Mollamahmutoglu, MuratThe 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.Öğe Time-Dependent Shear Strength Behavior of Superfine Cement-Stabilized Clayey Soil(Amer Concrete Inst, 2020) Mollamahmutoglu, Murat; Avcı, EyübhanIn this study, the goal was to investigate the shear strength properties of superfine cement (SC) stabilized clayey soil (CS). In this regard, standard compaction tests were run on the clayey soil specimens stabilized with 8, 10, and 12% SC to determine their optimum moisture contents and the maximum dry densities. Thereafter, unconsolidated undrained (UU) triaxial tests were conducted on them to find out their shear strength parameters and stress-strain characteristics at different time intervals under wet-cured and air-dried conditions. The shear strength parameters-namely the cohesion intercept and the internal friction angle of CS-increased with the stabilization of SC under both curing conditions. Additionally, the shear strength parameters of SC-stabilized CS were increased more with the increase of SC content and time under both curing conditions. The internal friction angles of air-dried specimens were higher than those of wet-cured specimens. On the other hand, the cohesion intercepts of wet-cured specimens were greater than those of air-dried specimens. The stress-strain behavior of CS was also influenced with the stabilization of SC such that as the stresses of CS were increased with the increase of SC content and time their strains decreased and they experienced brittle failures under both wet-cured and air-dried conditions.
