Dr. FATİH ÇELİK | Niğde University (original) (raw)

Papers by Dr. FATİH ÇELİK

European Journal of Environmental and Civil Engineering, 2020

This paper evaluates the unconfined compressive strength (UCS), stability (bleeding), modulus of ... more This paper evaluates the unconfined compressive strength (UCS), stability (bleeding), modulus of elasticity and failure patterns of cement-based grout mixtures that were prepared by placing of rice husk ash (RHA) with cement at various water to binder (w/b) ratios. In order to investigate these parameters, UCS and bleeding tests were conducted on the soilcrete samples that prepared at 5, 10, 20 and 30% replacement level of RHA with cement for .75, 1.00 and 1.25 w/b ratios. Test results showed that the UCS values of the samples for 28 day curing are higher than 1 MPa and E/q u ratios obtained from soilcrete mixtures were less than the corresponding value from slurry clay-cement mixes given in the literature. In addition, all bleeding test results are lower than the level of .5%. Finally, most of the mixtures prepared for this study failed along foliations.

Key Engineering Materials, 2020

This study was carried out to undrestand some specific problems that limit safe design and constr... more This study was carried out to undrestand some specific problems that limit safe design and construction of structures on problematic soils. An experimental study was undertaken to examine the influence of the rate of loading and moisture content on shear strength of organic soil. Influece of moisture content on interface friction between organic soil and structural material was also attempted. A commonly used soil in Iraq was prepared at varying moisture contents of 39, 57 and 75 %. The experimental results showed that the increase in water content will decrease the shear stress and the internal friction angle. An increase of the shear rate was found to decrease the shear stress and internal friction angle at all percetanges of water contents. Further, direct shear tests were carried out to detect the interface shear stress behavior between the organic soil and structural material. The results revealed that the increase in water content was shown to have significant negetavie effects on the interface internal friction and angle shear strength. Introductıon Shear strength is a significant property alongside other geotechnical properties in design and construction of structures. Shear strength often plays an essential role when any civil engineering application comes across soils which contain organic matter. Shear resistance is a concern factor at the construction of a standing construction equipment as well as at the end of construction in supporting the structure. Generally, organic soils posess low shear strength, and can be catigorized as 'problematic soils'. Accuracy in calculating the shear strength of these types of soils is limited to some variables, namely; origin of soil, moisture content, organic content, shear rate and degree of humification [1]. In the case of organic soil, the interface friction between the soil and construction material, such as wood, concrete and steel is found to be another important factor. One can argue that the shear strength of organic soils and hence, the angle of internal friction (peak or residual) is governed by several factors including; soil composition, initial stress state of the sample, soil structure, specimen size and rate of loading. The rate of loading, i.e. rate of strain, has been found to be one of the prominent factors influencing the obtained shear strength parameter [2]. Impact of the shear rate on the residual strength of cohesive soils was studied by many researchers [3, 4, 5]. In these studies, three types of residual strengths were observed when a slow shear rate was applied under drained condition followed by a fast shear rate. These residual strengths named by the effect of positive rate, neutral rate and negative rate. In addition, considerable works have been carried out on the performance of cohesionless soils under different shear rates [5, 6, 7]. Cassagrande and Shannon [6] were among the first to obtain the effect of strain rate on the shear resistance of soil. The researchers carried out triaxial tests on sands at confining pressures ranged from 30 to 90 kPa with strain rates up to 115 % per second. Cassagrande and Shannon [6] found that shear resistance of the dry sand has increased by approximately 10 % from static levels when tested at high rates of loading. The generated pore water pressure was dependent on the strain rate in the undrained triaxial tests. Therefore, the pore water pressure in the residual state was more likely dependent on the shear rate. In other words, the dependence of effective Key Engineering Materials

Construction and Building Materials Journal, 2020

h i g h l i g h t s Rheology and workability of the cement based grout treated with bottom ash (B... more h i g h l i g h t s Rheology and workability of the cement based grout treated with bottom ash (BA) were investigated. The substitution of BA to the grout mixtures has considerable effects on the rheological and fluidity properties. Rheological features are so critical for evaluating permeation grouting design parameters. Water to binder ratio (w/b) is dominant factor affecting rheological and workability properties of cement based grouts. a b s t r a c t This study presents the effects of rheological and fluidity features of cement based grouts incorporated with bottom ash (BA) as mineral additive on permeation grouting method. In this context, some experimental and analytical analyses were conducted and their results were presented. In terms of rheological and workability tests, the test program included 28 different mixtures having 0% (for control purposes), 5%, 10%, 15%, 20%, 25% and 30% bottom ash content and four water to binder ratios (w/b = 0.75, 1.00, 1.25 and 1.50). Plastic viscosity, apparent viscosity, and the yield stress of the mixtures based on rheological properties were measured for all mixtures. At the same time, marsh cone flow time, plate cohesion, and mini slump diameter in terms of workability features were obtained. In second part of this study, all rhe-ological properties obtained from the mixtures were used for evaluating permeation grout method based on two analytical flow models (radial and spherical flow models). All test results showed that rheological parameters (especially plastic viscosity) and workability properties of the cement based grouts incorporated with BA are very important for determining of the permeation grouting design parameters such as injection pressure.

Arabian Journal of Geosciences, 2019

The piled-raft foundation systems have started to be a very popular design method that is commonl... more The piled-raft foundation systems have started to be a very popular design method that is commonly used for especially high-rise buildings. In this foundation system, both raft and piles share the applied loads coming from the supper structures. There are several methods proposed by researchers in order to solve piled-raft foundation problems by simplified methods, approximate methods, and more sophisticated computer-based methods. These sophisticated computer-based solutions are not simply adapted to geotechnical works, and accessing these programs by everyone is not easy. The main purpose of this study is to present an easy and new technique for solving piled-raft problems with using 2D-FEM analysis combined with equivalent pier. In this study, design concepts of a pile-raft system prepared by 2D-FEM analysis combined with equivalent pier were presented. Furthermore, the test results obtained from this method were compared with the results that were taken from equivalent raft method and equivalent pier with single pile response in a sandy soil. A generic example of a piled-raft system including 3 × 3 number piles was designed, and its some properties such as length of pile (10-28 m), pier-soil stiffness ratio (1000-5000), and spacing between the piles (2-4 m) were evaluated and compared as variables. It was concluded from this study that equivalent pier with 2D-FEM analysis can make very similar predictions for calculating settlements of piled-raft system regarding on equivalent pier with single pile response method. As a result of this study: (1) as aspect ratio of piled-raft system increases, raft to pile stiffness ratio gradually increases for all s/d ratios, (2) the efficiency exponents obtained from this study ranges between 0.46 and 0.58 values, (3) stiffness of the piled-raft system gradually increases with increase of slenderness ratio for both two equivalent pier methods, and (4) as slenderness ratio increases, stiffness ratio of the piled-raft system contrarily decreases.

Geomechanics and Engineering, 2019

This study concluded the results of a research on the features of cement based permeation grout, ... more This study concluded the results of a research on the features of cement based permeation grout, based on some important grout parameters, such as the rheological properties (yield stress and viscosity), coefficient of permeability to grout (kG) and the inject ability of cement grout (N and Nc assessment), which govern the performance of cement based permeation grouting in porous media. Due to the limited knowledge of these important grout parameters and other influencing factors (filtration pressure, rate and time of injection and the grout volume) used in the field work, the application of cement based permeation grouting is still largely a trial and error process in the current practice, especially in the local construction industry. It is seen possible to use simple formulas in order to select the injection parameters and to evaluate their inter-relationship, as well as to optimize injection spacing and times with respect to injection source dimensions and in-situ permeability. The validity of spherical and cylindrical flow model was not verified by any past research works covered in the literature review. Therefore, a theoretical investigation including grout flow models and significant grout parameters for the design of permeation grouting was conducted in this study. This two grout flow models were applied for three grout mixes prepared for w/c=0.75, w/c=1.00 and w/c=1.25 in this study. The relations between injection times, radius, pump pressure and flow rate for both flow models were investigated and the results were presented. Furthermore, in order to investigate these two flow model, some rheological properties of the grout mixes, particle size distribution of the cement used in this study and some geotechnical properties of the sand used in this work were defined and presented.

Peat is found in many countries throughout the world where it can be generally seen in thick laye... more Peat is found in many countries throughout the world where it can be generally seen in thick layers in limited areas. Peat is an extreme form of soft soil and is considered problematic due to the low shear strength and large compressibility. This project presents laboratory finding on the compressibility and shear strength characteristics of fibrous peat with sand column. The peat used in the study is classified as fibrous peat and H 1 –H 4 in Von Post scale. Its liquid limit is 119%. In all tests, the peat used for the tests passing 2 mm and remain on .15 mm. The rounded sand used for making sand column is poorly graded passing from 2 mm sieve size and retaining on 1 mm sieve size. The tests conducted to investigate effect of area ratio of sand column on shear strength and compressibility of the peat. Three different area ratios were used for both compressibility and shear strength tests. Consolidation test results showed that when the area ratio increases compressibility characteristic of the peat improved. Shear strength of the organic soil was also affected from the sand column.

This paper reports the results of a study conducted to investigate the effects of rice husk powde... more This paper reports the results of a study conducted
to investigate the effects of rice husk powder (RHP) on the
rheological properties and the fluidity of grout mixtures. The
experiments were carried out with the grout mixtures including
of 4, 8, 12, 16 and 20% content of RHP and 0.75, 1.00,
1.25 and 1.50 ratios of water–cement. The purpose of the
study is to provide a new knowledge about using RHP as a
filler in cement grouts in order to improve the grout methods
and services, and achieve a good product performance.
Test results showed that the increase in RHP content in the
mix increases the plastic viscosity with all water–cement
ratios. At 0.75, 1.00 and 1.25 ratios of water–cement, the
grout mixtures showed shear-thinning behavior. On the other
hand, this behavior changes to shear-thickening behavior at
w/c = 1.50 at all RHP percentages. Experimental results
indicated that this waste product can be utilized as a filler
in cement grout for geotechnical application such as filling
large voids.

Understanding the basic phenomena controlling the mobilization of friction at the soil-solid surf... more Understanding the basic phenomena controlling the mobilization of friction at the soil-solid surface contact is essential for such traditional foundation structures such as piles, micropiles and anchors. In this study, the interface frictional characteristics of organic soil and a variety solid construction materials, including concrete, steel, and wood, were investigated. The interface friction angles of organic soil-solid surfaces were determined for different water content and granular soil content. In addition, the relationship between surface roughnesses and interface friction was investigated. All tests in this study were performed using a direct shear test device under different normal stresses. The test results showed that the frictional resistance between construction material and organic soil is affected by the water and granular soil content of the organic soil, the type of material, and the surface roughness.

This study was carried out with an intention to observe any sign of improvement of clayey soil du... more This study was carried out with an intention to observe any sign of improvement of clayey soil due to addition of waste soda lime glass powder (WSLGP). Waste soda lime glasses were crushed and sieved through #200 (75 μm) sieve and mixed with clay in 3, 6, 9, and 12% in dry weight of the clay. Strength and consistency test were carried out on mixed samples after curing. The test results indicated that the addition of WSLGP into clay has a significant effect on the strength and consistency properties of the clay.

This work presents an investigation of the effect of waste aluminum beverage cans strips on stren... more This work presents an investigation of the effect of waste aluminum beverage cans strips on strength and swelling properties of lean clay. Waste beverage cans (WBC) were cut into 5 mm strips and mixed with soil in 2, 4, 6, 8, and 10 % (dry weight of soil) before use. Three standard tests were carried on the prepared samples: compaction, free swelling, and California Bering Ratio (CBR). Test results showed that WBC significantly affected the compaction characteristics, swelling and strength properties of the clay.

The paper presents the results of series of direct shear tests made on recycled waste expanded po... more The paper presents the results of series of direct shear tests made on recycled waste expanded polystyrene foams (EPS). Waste EPS were thermally modified in an oven at 130 o C through 15 minutes and crushed into aggregate size before tested. Heat treatment of the EPS increased its density from 15 kg/m 3 to nearly 200 kg/m 3. Shear strength behavior of modified EPS were investigated in loose and dense states under three different normal stresses. The test results showed that shear strength behavior of modified EPS is similar to that of sand. Internal friction angle of modified waste EPS in the dense state is higher than of loose state.

The fluidity and rheological properties of the grout mixtures treated with rice husk powder (RHP)... more The fluidity and rheological properties of the grout mixtures treated with rice husk powder (RHP) were studied. The experimen ts were
done by using different RHP content (%4, %8, %12, %16 and %20 respectively) with cement grouts proportioned with different water
to cement ratio (0.75, 1.00, 1.25 and 1.50). This experiment aims to help contribute to the industry in saving the environmen t, to
encourage the municipality to find solutions regarding the disposal to landfills of waste materials and save the environment, to
provide new knowledge to the contractors and developers on how to improve the grout methods and services by using rice husk, and
to sustain good product performance and meet recycling goals. Observations from the tests performed were conducted in the
laboratory where precise data were gathered and completely attained.

This paper investigates the fluidity and rheological properties of the cement based grout mixed w... more This paper investigates the fluidity and rheological properties of the cement based grout mixed with rice husk ash (RHA). The experimental program consisted of fifteen different mixture having 5%, 10%, 20%, and 30% RHA content and three different water to binder ratios (w/b = 0.75%, 1.00%, and 1.25%). Workability properties (marsh cone flow time, plate cohesion, and mini slump diameter), plastic viscosity, apparent viscosity, and the yield stress of the mixtures were determined. Test results showed that increasing replacement level for the RHA amount increases marsh cone flow time, plate cohesion, plastic and apparent viscosity, and the yield stress, but also decreases mini slump diameter. Shear thickening and pseudo-plastic behavior was observed for high RHA content for w/b ratios greater than 1.00.

The aim of this work; To observe the effect of rice husk powder (RHP) that is an organic waste ma... more The aim of this work; To observe the effect of rice husk powder (RHP) that is an organic waste material on the rheological and mechanical properties of the grout used as a soil improvement material at the soils that have bearing capacity and permeability problems. The investigates the fluidity and rheological properties of the cement based grout mixed with rice husk powder (RHP). The experimental program consisted of twenty-four different mixture having 4%, 8%, 12%, 16% and 20%. RHP content and four different water to cement ratios (w/c= 0.75, 1.00, 1.25 and 1.50). Workability properties (marsh cone flow time, plate cohesion, and mini slump diameter), plastic viscosity, apparent viscosity, and the yield stress of the mixtures were determined. Test results showed that increasing replacement level for the RHP amount increases marsh cone flow time, plate cohesion, plastic and apparent viscosity, and the yield stress, but also decreases mini slump diameter. Shear thickening and pseudo-plastic behavior was observed for high RHP content for w/c ratios greater than 1.25.

This paper investigates the fluidity and rheological properties of the cement based grout mixed w... more This paper investigates the fluidity and rheological properties of the cement based grout mixed with rice
husk ash (RHA). The experimental program consisted of fifteen different mixture having 5%, 10%, 20%, and
30% RHA content and three different water to binder ratios (w/b = 0.75%, 1.00%, and 1.25%). Workability
properties (marsh cone flow time, plate cohesion, and mini slump diameter), plastic viscosity, apparent
viscosity, and the yield stress of the mixtures were determined. Test results showed that increasing
replacement level for the RHA amount increases marsh cone flow time, plate cohesion, plastic and
apparent viscosity, and the yield stress, but also decreases mini slump diameter. Shear thickening and
pseudo-plastic behavior was observed for high RHA content for w/b ratios greater than 1.00.

This article presents the result of laboratory study conducted on expansive soil specimens treate... more This article presents the result of laboratory study conducted on expansive soil specimens
treated with lignin, rice husk powder (RHP) and rice husk ash (RHA). The amount of lignin produced from
paper industry and RHP were varied from 0 to 20% and RHA from 0 to 10% by weight. The treated
specimens were subjected to unconfined compressive strength (UCS),swelling test and Atterberg limit tests.
The effect of additives on UCS and atterberg limit test results were reported. It was observed that the
additives and curing duration had a significant effect on the strength value of treated specimens. Generally
(except the sample treated with 20% RHP for 3-day) with increasing additive and curing duration the UCS
value increases. A RHP content of 15% was found to be the optimum with regard to 3-day cure UCS.

This study focused on the effect of particle size of sandy soil on bacterial calcium carbonate pr... more This study focused on the effect of particle size of sandy soil on bacterial calcium
carbonate precipitation (BCCP) . Four samples of sandy soil in different particle size
(150-300), (300-600), (600-1mm) and (1mm-2mm), were prepared in glass boxes
having dimension of 6x6x2 cm were treated by immersing in bacterial medium (Bacillus
pasteurii, urea, and CaCl2) for 4 days. The samples were treated by urea medium and
CaCl2 every 6 hours during this treatment period. Throughout the treatment time change in
pH values were monitored each 6 hour. Also, amount of calcium carbonate in all samples
were determined by using calcimeter test at the end of treatment. The test results showed
that the pH values fluctuated between (9-9.3) during treatment stage for all samples. This
range of the pH values indicates that the treatment medium is appropriate for BCCP. It was
also found that the amount of precipitated calcium carbonate in occurred in all samples but
in different percentage, the maximum value of CaCo3 monitored in sandy sample with
particle siaze between (600-1mm) , while the minimum value monitored in sandy sample
with particle size between (1mm-2mm). The results were supported by Scanning electron
microscopy (SEM) analysis and energy-dispersive x-ray (EDX) analysis.

In past few years, the use of bacterial calcium carbonate precipitation (biocementation) has beco... more In past few years, the use of bacterial calcium carbonate precipitation (biocementation) has
become popular as a ground improvement technique for sandy soil. However, this technique was not applied
to organic soil. This study focused on bacterial calcium carbonate precipitation and its effect on permeability
in organic soil. A special injection system was prepared for inducing bacterial solution to the samples. The
bacterial solution supplied to the samples by gravity for 4 days in specific molds designed for this work.
Calcite precipitation was observed by monitoring pH value and measuring amount of calcium carbonate.
Change in the permeability was measured before and after biocementation. The test results showed that the
pH values indicates that the treatment medium is appropriate for calcite precipitation, and amount of
precipitated calcium carbonate in organic soil increased about 20% from untreated one. It was also found
that the biocementation can be considered as an effective method for reducing permeability of organic soil.
The results were supported by Scanning electron microscopy (SEM) analysis and energy-dispersive x-ray
(EDX) analysis.

In this study, the effect of sand content on compaction, shear strength, and compressibility of f... more In this study, the effect of sand content on compaction,
shear strength, and compressibility of fibrous peat
was investigated. The sand used for the study is rounded
and poorly graded passing 2-mm sieve and retaining on 1-
mm sieve. Samples were prepared by adding 10, 20, 30, 40,
and 50%sand by weight, respectively. Standard Proctor tests
were carried out for each mixture to determine the optimum
moisture content and maximum dry densities of the samples.
Shear strength and consolidation tests were performed on five
different mixtures that were prepared at their optimum moisture
content andmaximumdry densities.Tests results showed
that the amount of sand content has a significant effect on
compaction, shear strength, and compressibility parameters
of fibrous peat.

In this study, effect of different sand content on compaction properties of organic soil was inve... more In this study, effect of different sand content on compaction properties of organic soil was investigated. Organic soil used in the study was taken from Sakarya region, Turkey. Compaction test was carried out with standard 2.5 kg hammer. Five different sand content was used that are 10%, 20%, 30%, 40% and 50%. Test results showed that sand content has an important effect on both dry density and optimum moisture content. When the sand content incresed in the organic soil optimum moisture content reduced and the maximum dry density increased.

European Journal of Environmental and Civil Engineering, 2020

This paper evaluates the unconfined compressive strength (UCS), stability (bleeding), modulus of ... more This paper evaluates the unconfined compressive strength (UCS), stability (bleeding), modulus of elasticity and failure patterns of cement-based grout mixtures that were prepared by placing of rice husk ash (RHA) with cement at various water to binder (w/b) ratios. In order to investigate these parameters, UCS and bleeding tests were conducted on the soilcrete samples that prepared at 5, 10, 20 and 30% replacement level of RHA with cement for .75, 1.00 and 1.25 w/b ratios. Test results showed that the UCS values of the samples for 28 day curing are higher than 1 MPa and E/q u ratios obtained from soilcrete mixtures were less than the corresponding value from slurry clay-cement mixes given in the literature. In addition, all bleeding test results are lower than the level of .5%. Finally, most of the mixtures prepared for this study failed along foliations.

Key Engineering Materials, 2020

This study was carried out to undrestand some specific problems that limit safe design and constr... more This study was carried out to undrestand some specific problems that limit safe design and construction of structures on problematic soils. An experimental study was undertaken to examine the influence of the rate of loading and moisture content on shear strength of organic soil. Influece of moisture content on interface friction between organic soil and structural material was also attempted. A commonly used soil in Iraq was prepared at varying moisture contents of 39, 57 and 75 %. The experimental results showed that the increase in water content will decrease the shear stress and the internal friction angle. An increase of the shear rate was found to decrease the shear stress and internal friction angle at all percetanges of water contents. Further, direct shear tests were carried out to detect the interface shear stress behavior between the organic soil and structural material. The results revealed that the increase in water content was shown to have significant negetavie effects on the interface internal friction and angle shear strength. Introductıon Shear strength is a significant property alongside other geotechnical properties in design and construction of structures. Shear strength often plays an essential role when any civil engineering application comes across soils which contain organic matter. Shear resistance is a concern factor at the construction of a standing construction equipment as well as at the end of construction in supporting the structure. Generally, organic soils posess low shear strength, and can be catigorized as 'problematic soils'. Accuracy in calculating the shear strength of these types of soils is limited to some variables, namely; origin of soil, moisture content, organic content, shear rate and degree of humification [1]. In the case of organic soil, the interface friction between the soil and construction material, such as wood, concrete and steel is found to be another important factor. One can argue that the shear strength of organic soils and hence, the angle of internal friction (peak or residual) is governed by several factors including; soil composition, initial stress state of the sample, soil structure, specimen size and rate of loading. The rate of loading, i.e. rate of strain, has been found to be one of the prominent factors influencing the obtained shear strength parameter [2]. Impact of the shear rate on the residual strength of cohesive soils was studied by many researchers [3, 4, 5]. In these studies, three types of residual strengths were observed when a slow shear rate was applied under drained condition followed by a fast shear rate. These residual strengths named by the effect of positive rate, neutral rate and negative rate. In addition, considerable works have been carried out on the performance of cohesionless soils under different shear rates [5, 6, 7]. Cassagrande and Shannon [6] were among the first to obtain the effect of strain rate on the shear resistance of soil. The researchers carried out triaxial tests on sands at confining pressures ranged from 30 to 90 kPa with strain rates up to 115 % per second. Cassagrande and Shannon [6] found that shear resistance of the dry sand has increased by approximately 10 % from static levels when tested at high rates of loading. The generated pore water pressure was dependent on the strain rate in the undrained triaxial tests. Therefore, the pore water pressure in the residual state was more likely dependent on the shear rate. In other words, the dependence of effective Key Engineering Materials

Construction and Building Materials Journal, 2020

h i g h l i g h t s Rheology and workability of the cement based grout treated with bottom ash (B... more h i g h l i g h t s Rheology and workability of the cement based grout treated with bottom ash (BA) were investigated. The substitution of BA to the grout mixtures has considerable effects on the rheological and fluidity properties. Rheological features are so critical for evaluating permeation grouting design parameters. Water to binder ratio (w/b) is dominant factor affecting rheological and workability properties of cement based grouts. a b s t r a c t This study presents the effects of rheological and fluidity features of cement based grouts incorporated with bottom ash (BA) as mineral additive on permeation grouting method. In this context, some experimental and analytical analyses were conducted and their results were presented. In terms of rheological and workability tests, the test program included 28 different mixtures having 0% (for control purposes), 5%, 10%, 15%, 20%, 25% and 30% bottom ash content and four water to binder ratios (w/b = 0.75, 1.00, 1.25 and 1.50). Plastic viscosity, apparent viscosity, and the yield stress of the mixtures based on rheological properties were measured for all mixtures. At the same time, marsh cone flow time, plate cohesion, and mini slump diameter in terms of workability features were obtained. In second part of this study, all rhe-ological properties obtained from the mixtures were used for evaluating permeation grout method based on two analytical flow models (radial and spherical flow models). All test results showed that rheological parameters (especially plastic viscosity) and workability properties of the cement based grouts incorporated with BA are very important for determining of the permeation grouting design parameters such as injection pressure.

Arabian Journal of Geosciences, 2019

The piled-raft foundation systems have started to be a very popular design method that is commonl... more The piled-raft foundation systems have started to be a very popular design method that is commonly used for especially high-rise buildings. In this foundation system, both raft and piles share the applied loads coming from the supper structures. There are several methods proposed by researchers in order to solve piled-raft foundation problems by simplified methods, approximate methods, and more sophisticated computer-based methods. These sophisticated computer-based solutions are not simply adapted to geotechnical works, and accessing these programs by everyone is not easy. The main purpose of this study is to present an easy and new technique for solving piled-raft problems with using 2D-FEM analysis combined with equivalent pier. In this study, design concepts of a pile-raft system prepared by 2D-FEM analysis combined with equivalent pier were presented. Furthermore, the test results obtained from this method were compared with the results that were taken from equivalent raft method and equivalent pier with single pile response in a sandy soil. A generic example of a piled-raft system including 3 × 3 number piles was designed, and its some properties such as length of pile (10-28 m), pier-soil stiffness ratio (1000-5000), and spacing between the piles (2-4 m) were evaluated and compared as variables. It was concluded from this study that equivalent pier with 2D-FEM analysis can make very similar predictions for calculating settlements of piled-raft system regarding on equivalent pier with single pile response method. As a result of this study: (1) as aspect ratio of piled-raft system increases, raft to pile stiffness ratio gradually increases for all s/d ratios, (2) the efficiency exponents obtained from this study ranges between 0.46 and 0.58 values, (3) stiffness of the piled-raft system gradually increases with increase of slenderness ratio for both two equivalent pier methods, and (4) as slenderness ratio increases, stiffness ratio of the piled-raft system contrarily decreases.

Geomechanics and Engineering, 2019

This study concluded the results of a research on the features of cement based permeation grout, ... more This study concluded the results of a research on the features of cement based permeation grout, based on some important grout parameters, such as the rheological properties (yield stress and viscosity), coefficient of permeability to grout (kG) and the inject ability of cement grout (N and Nc assessment), which govern the performance of cement based permeation grouting in porous media. Due to the limited knowledge of these important grout parameters and other influencing factors (filtration pressure, rate and time of injection and the grout volume) used in the field work, the application of cement based permeation grouting is still largely a trial and error process in the current practice, especially in the local construction industry. It is seen possible to use simple formulas in order to select the injection parameters and to evaluate their inter-relationship, as well as to optimize injection spacing and times with respect to injection source dimensions and in-situ permeability. The validity of spherical and cylindrical flow model was not verified by any past research works covered in the literature review. Therefore, a theoretical investigation including grout flow models and significant grout parameters for the design of permeation grouting was conducted in this study. This two grout flow models were applied for three grout mixes prepared for w/c=0.75, w/c=1.00 and w/c=1.25 in this study. The relations between injection times, radius, pump pressure and flow rate for both flow models were investigated and the results were presented. Furthermore, in order to investigate these two flow model, some rheological properties of the grout mixes, particle size distribution of the cement used in this study and some geotechnical properties of the sand used in this work were defined and presented.

Peat is found in many countries throughout the world where it can be generally seen in thick laye... more Peat is found in many countries throughout the world where it can be generally seen in thick layers in limited areas. Peat is an extreme form of soft soil and is considered problematic due to the low shear strength and large compressibility. This project presents laboratory finding on the compressibility and shear strength characteristics of fibrous peat with sand column. The peat used in the study is classified as fibrous peat and H 1 –H 4 in Von Post scale. Its liquid limit is 119%. In all tests, the peat used for the tests passing 2 mm and remain on .15 mm. The rounded sand used for making sand column is poorly graded passing from 2 mm sieve size and retaining on 1 mm sieve size. The tests conducted to investigate effect of area ratio of sand column on shear strength and compressibility of the peat. Three different area ratios were used for both compressibility and shear strength tests. Consolidation test results showed that when the area ratio increases compressibility characteristic of the peat improved. Shear strength of the organic soil was also affected from the sand column.

This paper reports the results of a study conducted to investigate the effects of rice husk powde... more This paper reports the results of a study conducted
to investigate the effects of rice husk powder (RHP) on the
rheological properties and the fluidity of grout mixtures. The
experiments were carried out with the grout mixtures including
of 4, 8, 12, 16 and 20% content of RHP and 0.75, 1.00,
1.25 and 1.50 ratios of water–cement. The purpose of the
study is to provide a new knowledge about using RHP as a
filler in cement grouts in order to improve the grout methods
and services, and achieve a good product performance.
Test results showed that the increase in RHP content in the
mix increases the plastic viscosity with all water–cement
ratios. At 0.75, 1.00 and 1.25 ratios of water–cement, the
grout mixtures showed shear-thinning behavior. On the other
hand, this behavior changes to shear-thickening behavior at
w/c = 1.50 at all RHP percentages. Experimental results
indicated that this waste product can be utilized as a filler
in cement grout for geotechnical application such as filling
large voids.

Understanding the basic phenomena controlling the mobilization of friction at the soil-solid surf... more Understanding the basic phenomena controlling the mobilization of friction at the soil-solid surface contact is essential for such traditional foundation structures such as piles, micropiles and anchors. In this study, the interface frictional characteristics of organic soil and a variety solid construction materials, including concrete, steel, and wood, were investigated. The interface friction angles of organic soil-solid surfaces were determined for different water content and granular soil content. In addition, the relationship between surface roughnesses and interface friction was investigated. All tests in this study were performed using a direct shear test device under different normal stresses. The test results showed that the frictional resistance between construction material and organic soil is affected by the water and granular soil content of the organic soil, the type of material, and the surface roughness.

This study was carried out with an intention to observe any sign of improvement of clayey soil du... more This study was carried out with an intention to observe any sign of improvement of clayey soil due to addition of waste soda lime glass powder (WSLGP). Waste soda lime glasses were crushed and sieved through #200 (75 μm) sieve and mixed with clay in 3, 6, 9, and 12% in dry weight of the clay. Strength and consistency test were carried out on mixed samples after curing. The test results indicated that the addition of WSLGP into clay has a significant effect on the strength and consistency properties of the clay.

This work presents an investigation of the effect of waste aluminum beverage cans strips on stren... more This work presents an investigation of the effect of waste aluminum beverage cans strips on strength and swelling properties of lean clay. Waste beverage cans (WBC) were cut into 5 mm strips and mixed with soil in 2, 4, 6, 8, and 10 % (dry weight of soil) before use. Three standard tests were carried on the prepared samples: compaction, free swelling, and California Bering Ratio (CBR). Test results showed that WBC significantly affected the compaction characteristics, swelling and strength properties of the clay.

The paper presents the results of series of direct shear tests made on recycled waste expanded po... more The paper presents the results of series of direct shear tests made on recycled waste expanded polystyrene foams (EPS). Waste EPS were thermally modified in an oven at 130 o C through 15 minutes and crushed into aggregate size before tested. Heat treatment of the EPS increased its density from 15 kg/m 3 to nearly 200 kg/m 3. Shear strength behavior of modified EPS were investigated in loose and dense states under three different normal stresses. The test results showed that shear strength behavior of modified EPS is similar to that of sand. Internal friction angle of modified waste EPS in the dense state is higher than of loose state.

The fluidity and rheological properties of the grout mixtures treated with rice husk powder (RHP)... more The fluidity and rheological properties of the grout mixtures treated with rice husk powder (RHP) were studied. The experimen ts were
done by using different RHP content (%4, %8, %12, %16 and %20 respectively) with cement grouts proportioned with different water
to cement ratio (0.75, 1.00, 1.25 and 1.50). This experiment aims to help contribute to the industry in saving the environmen t, to
encourage the municipality to find solutions regarding the disposal to landfills of waste materials and save the environment, to
provide new knowledge to the contractors and developers on how to improve the grout methods and services by using rice husk, and
to sustain good product performance and meet recycling goals. Observations from the tests performed were conducted in the
laboratory where precise data were gathered and completely attained.

This paper investigates the fluidity and rheological properties of the cement based grout mixed w... more This paper investigates the fluidity and rheological properties of the cement based grout mixed with rice husk ash (RHA). The experimental program consisted of fifteen different mixture having 5%, 10%, 20%, and 30% RHA content and three different water to binder ratios (w/b = 0.75%, 1.00%, and 1.25%). Workability properties (marsh cone flow time, plate cohesion, and mini slump diameter), plastic viscosity, apparent viscosity, and the yield stress of the mixtures were determined. Test results showed that increasing replacement level for the RHA amount increases marsh cone flow time, plate cohesion, plastic and apparent viscosity, and the yield stress, but also decreases mini slump diameter. Shear thickening and pseudo-plastic behavior was observed for high RHA content for w/b ratios greater than 1.00.

The aim of this work; To observe the effect of rice husk powder (RHP) that is an organic waste ma... more The aim of this work; To observe the effect of rice husk powder (RHP) that is an organic waste material on the rheological and mechanical properties of the grout used as a soil improvement material at the soils that have bearing capacity and permeability problems. The investigates the fluidity and rheological properties of the cement based grout mixed with rice husk powder (RHP). The experimental program consisted of twenty-four different mixture having 4%, 8%, 12%, 16% and 20%. RHP content and four different water to cement ratios (w/c= 0.75, 1.00, 1.25 and 1.50). Workability properties (marsh cone flow time, plate cohesion, and mini slump diameter), plastic viscosity, apparent viscosity, and the yield stress of the mixtures were determined. Test results showed that increasing replacement level for the RHP amount increases marsh cone flow time, plate cohesion, plastic and apparent viscosity, and the yield stress, but also decreases mini slump diameter. Shear thickening and pseudo-plastic behavior was observed for high RHP content for w/c ratios greater than 1.25.

This paper investigates the fluidity and rheological properties of the cement based grout mixed w... more This paper investigates the fluidity and rheological properties of the cement based grout mixed with rice
husk ash (RHA). The experimental program consisted of fifteen different mixture having 5%, 10%, 20%, and
30% RHA content and three different water to binder ratios (w/b = 0.75%, 1.00%, and 1.25%). Workability
properties (marsh cone flow time, plate cohesion, and mini slump diameter), plastic viscosity, apparent
viscosity, and the yield stress of the mixtures were determined. Test results showed that increasing
replacement level for the RHA amount increases marsh cone flow time, plate cohesion, plastic and
apparent viscosity, and the yield stress, but also decreases mini slump diameter. Shear thickening and
pseudo-plastic behavior was observed for high RHA content for w/b ratios greater than 1.00.

This article presents the result of laboratory study conducted on expansive soil specimens treate... more This article presents the result of laboratory study conducted on expansive soil specimens
treated with lignin, rice husk powder (RHP) and rice husk ash (RHA). The amount of lignin produced from
paper industry and RHP were varied from 0 to 20% and RHA from 0 to 10% by weight. The treated
specimens were subjected to unconfined compressive strength (UCS),swelling test and Atterberg limit tests.
The effect of additives on UCS and atterberg limit test results were reported. It was observed that the
additives and curing duration had a significant effect on the strength value of treated specimens. Generally
(except the sample treated with 20% RHP for 3-day) with increasing additive and curing duration the UCS
value increases. A RHP content of 15% was found to be the optimum with regard to 3-day cure UCS.

This study focused on the effect of particle size of sandy soil on bacterial calcium carbonate pr... more This study focused on the effect of particle size of sandy soil on bacterial calcium
carbonate precipitation (BCCP) . Four samples of sandy soil in different particle size
(150-300), (300-600), (600-1mm) and (1mm-2mm), were prepared in glass boxes
having dimension of 6x6x2 cm were treated by immersing in bacterial medium (Bacillus
pasteurii, urea, and CaCl2) for 4 days. The samples were treated by urea medium and
CaCl2 every 6 hours during this treatment period. Throughout the treatment time change in
pH values were monitored each 6 hour. Also, amount of calcium carbonate in all samples
were determined by using calcimeter test at the end of treatment. The test results showed
that the pH values fluctuated between (9-9.3) during treatment stage for all samples. This
range of the pH values indicates that the treatment medium is appropriate for BCCP. It was
also found that the amount of precipitated calcium carbonate in occurred in all samples but
in different percentage, the maximum value of CaCo3 monitored in sandy sample with
particle siaze between (600-1mm) , while the minimum value monitored in sandy sample
with particle size between (1mm-2mm). The results were supported by Scanning electron
microscopy (SEM) analysis and energy-dispersive x-ray (EDX) analysis.

In past few years, the use of bacterial calcium carbonate precipitation (biocementation) has beco... more In past few years, the use of bacterial calcium carbonate precipitation (biocementation) has
become popular as a ground improvement technique for sandy soil. However, this technique was not applied
to organic soil. This study focused on bacterial calcium carbonate precipitation and its effect on permeability
in organic soil. A special injection system was prepared for inducing bacterial solution to the samples. The
bacterial solution supplied to the samples by gravity for 4 days in specific molds designed for this work.
Calcite precipitation was observed by monitoring pH value and measuring amount of calcium carbonate.
Change in the permeability was measured before and after biocementation. The test results showed that the
pH values indicates that the treatment medium is appropriate for calcite precipitation, and amount of
precipitated calcium carbonate in organic soil increased about 20% from untreated one. It was also found
that the biocementation can be considered as an effective method for reducing permeability of organic soil.
The results were supported by Scanning electron microscopy (SEM) analysis and energy-dispersive x-ray
(EDX) analysis.

In this study, the effect of sand content on compaction, shear strength, and compressibility of f... more In this study, the effect of sand content on compaction,
shear strength, and compressibility of fibrous peat
was investigated. The sand used for the study is rounded
and poorly graded passing 2-mm sieve and retaining on 1-
mm sieve. Samples were prepared by adding 10, 20, 30, 40,
and 50%sand by weight, respectively. Standard Proctor tests
were carried out for each mixture to determine the optimum
moisture content and maximum dry densities of the samples.
Shear strength and consolidation tests were performed on five
different mixtures that were prepared at their optimum moisture
content andmaximumdry densities.Tests results showed
that the amount of sand content has a significant effect on
compaction, shear strength, and compressibility parameters
of fibrous peat.

In this study, effect of different sand content on compaction properties of organic soil was inve... more In this study, effect of different sand content on compaction properties of organic soil was investigated. Organic soil used in the study was taken from Sakarya region, Turkey. Compaction test was carried out with standard 2.5 kg hammer. Five different sand content was used that are 10%, 20%, 30%, 40% and 50%. Test results showed that sand content has an important effect on both dry density and optimum moisture content. When the sand content incresed in the organic soil optimum moisture content reduced and the maximum dry density increased.