Unconfined Compressive Strength

The continuous growth in civilization and population have led to upsurge in generation of construction and demolition (C&D) wastes. A considerable part of C&D wastes is gypsum wastes that together with its derivatives are classified as a group of binding agents in soil stabilization and immobilization and upgrading soil durability. In this study, the possibility of using gypseous wastes as a binding agent was investigated. Moreover, soil stabilized with recycled gypsum was tested under different dry-wet cycles as well as multiple dry-rewetting to assess the stability of improved soil. Different amounts of gaseous waste (0, 5, 10, and 20%) and 5% cement and 5% lime were added to clay soil at various curing conditions (0, 7, 14, and 21 days). Then, durability of samples was tested by wetting/drying cycles (0, 1, 2, and 3 cycles). Soil characteristics including compaction, unconfined compression strength, Atterberg limits and soil durability were assessed for all samples. Results demonstrated significant increase of the unconfined compressive strength in clay by addition of gypsum waste, cement, and lime. However, we detected a significant reduction in the unconfined compressive strength of the samples in the third cycle of wetting-drying test.

To attain desirable strength of soil, soil reinforcement has been playing a pivotal role since many decades. Although there are many well established methods to reinforce the soil, but now-a-days people are looking for low-cost reinforcing materials. In Bangladesh jute waste is not being used effectively, although jute production is quite good in amount. From this point of view, in this study jute fiber is selected as reinforcing material and focused on improvement of compressive strength of soil with this. Varying proportions of Jute fiber as 1%, 2%, 3% and 4% have been mixed with soil to make the samples to be tested. The result indicated that the sample prepared with 3% of jute fiber gives the highest value in Unconfined Compressive Strength (UCS) test, and adding more than 3% of jute fiber tends to decrease the UCS value. As this study has been done keeping in mind about the embankment construction process in the coastal zones of Bangladesh, where grass turfing is done to protect soil from erosion and inorganic fertilizer is used to grow up the grass which has long term adverse effect on environment. On the other hand jute is 100% biodegradable, when it comes to contact of moist soil, after a certain period it acts as natural fertilizer that helps to grow up the grass and make the root of grass stronger to hold the soil.

Red mud is a waste material generated by the Bayer Process widely used to produce alumina from bauxite throughout the world. Approximately, 35% to 40% per ton of bauxite treated using the Bayer Process ends up as red mud waste. Because of storing issues, the waste negatively affects the environment. To solve this problem, it is essential to investigate different uses for red mud waste. The potential use of red mud for the preparation of stabilization material is presented in this study. This study examines the effects of red mud on the unconfined compressive strength, hydraulic conductivity, and swelling percentage of compacted clay liners as a hydraulic barrier. The test results show that compacted clay samples containing red mud and cement–red mud additives have a high compressive strength and decreased the hydraulic conductivity and swelling percentage as compared to natural clay samples. Consequently, it is concluded that red mud and cement–red mud materials can be successfully used for the stabilization of clay liners in geotechnical applications.

In the new age ground improvement techniques, pertaining to strengthen the weaker soils and to improve the strength characteristics and stiffness of these types of soils, cement stabilization is proved to be more effective. In the cement stabilization, the "curing time" is the key factor in the context of strength gain of the soilcement mixture. Limited literature shows the importance of the curing conditions, mainly time. Also, it has been found that in nature, where the ground water is deeper, the use of such mixtures, especially during grouting are never considered for curing. Keeping this in view, an attempt is made to study the effect of curing time on the strength characteristics of cement treated soil and also to show the engineering behavior in various properties which includes the compaction, compressibility and the shear strength parameters. To achieve this, laboratory tests have been conducted for various types of soils treated with different types of cements, varying the percentages were performed. The results show that the curing time has a significant effect on the unconfined compressive strength and it is found that on the addition of cement content, the engineering properties are also affected.

Cement-Treated Base (CTB) is a non-conventional method used in road bases materials to improve its engineering properties due to the hardening of cement when moisture is present and extends the period of curing times. This study investigates the effects of cement additive on properties of base layer using laboratory mechanistic evaluation of stabilized soil mixtures. Laboratory tests conducted were Unconfined Compressive Strength (UCS), Indirect Tension test for Resilient Modulus (ITRM) and Flexure Strength (FS) tests. The results revealed that by adding Portland cement, the mechanical properties of the mixture have improved where the UCS is found to be an important quality indicator. In addition, the variables that influenced these tests, which are cement content, curing time, moisture content, and dry density, play important role to determine the performance of CTB. This paper presents the finding of a correlation conducted to analyse the influences of these variables using regression and ANOVA to establish significant models with the aim of predicting the strength base on mixture parameters.

This paper reports the results of advanced data analysis involving artificial neural networks for the prediction of the unconfined compressive strength of granite using only two non-destructive test indexes. A data-independent site-independent unbiased database comprising 182 datasets from non-destructive tests reported in the literature was compiled and used to train and develop artificial neural networks for the prediction of the unconfined compressive strength of granite. The results show that the optimum artificial network developed in this research predicts the unconfined compressive strength of weak to very strong granites (20.3-198.15 MPa) with less than ±20% deviation from the experimental data for 70% of the specimen and significantly outperforms a number of available models available in the literature. The results also raise interesting questions with regards to the suitability of the Pearson correlation coefficient in assessing the prediction accuracy of models.

Soft clays are widely distributed in Missouri, United States. Due to their relatively low strength and high compressibility, subgrade construction in soft clays has encountered many difficulties. In recent practice, the use of fly ash (FA) along with lime to tackle soft subgrade problems has shown promising results. The effectiveness of Class C FA and lime kiln dust (LKD) in clay subgrade stabilization is examined in this research. Scanning electron microscopic (SEM) analysis, proctor compaction tests, unconfined compression tests, and resilient modulus tests were carried out on the FA and LKD modified soil mixtures. Test specimens were prepared at optimum water content and tested at various curing periods. The test specimens were reconstituted by static compression. Test results revealed that the addition of Class C FA could increase the dry unit weight of the FA treated soil, enhance the unconfined compressive strength, and improve the resilient modulus. Regression equations were developed to correlate the resilient modulus with curing time. The mechanism of FA stabilization was discussed based on the SEM results and the measurement of the electrical conductivity of the FA-soil-water system. Correlations between the unconfined compressive strength and resilient modulus were developed. It is concluded that subgrade stabilization with Class C FA and LKD are cost-effective for road-base construction. ASCE 04014199-1 J. Mater. Civ. Eng. J. Mater. Civ. Eng. Downloaded from ascelibrary.org by LIBRARY PERIODICALS on 08/22/14. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04014199-2 J. Mater. Civ. Eng. J. Mater. Civ. Eng. Downloaded from ascelibrary.org by LIBRARY PERIODICALS on 08/22/14. Copyright ASCE. For personal use only; all rights reserved. Atchison Soil Atchison 10%FA Atchison 15%FA Atchison 20%FA Atchison 4%LKD Atchison 8%LKD Putnam Soil Putnam 10%FA Putnam 15%FA Putnam 20%FA Putnam 4%LKD Putnam 8%LKD Fig. 2. Moisture-density relationships of the treated and untreated clays © ASCE 04014199-3 J. Mater. Civ. Eng. J. Mater. Civ. Eng. Downloaded from ascelibrary.org by LIBRARY PERIODICALS on 08/22/14. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04014199-4 J. Mater. Civ. Eng. J. Mater. Civ. Eng. Downloaded from ascelibrary.org by LIBRARY PERIODICALS on 08/22/14. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04014199-6 J. Mater. Civ. Eng. J. Mater. Civ. Eng. Downloaded from ascelibrary.org by LIBRARY PERIODICALS on 08/22/14. Copyright ASCE. For personal use only; all rights reserved. © ASCE 04014199-7 J. Mater. Civ. Eng. J. Mater. Civ. Eng. Downloaded from ascelibrary.org by LIBRARY PERIODICALS on 08/22/14.

Peaty soils due to high compressibility and low strength under loads are not suitable for engineering construction projects, road and building construction as well. Decrease of compressibility as well as increase in strength of peat can be obtained by chemical stabilization. Lime-stabilization is a common, applicable and economical approach that can improve geotechnical properties of peat soils. In this study, some important geotechnical properties of peat including compressive strength and elasticplastic behavior are investigated. In this paper, laboratory samples of soil with different percentage of soil and lime has been studied-besides, administration of different tests for improving the Geo technical properties of stabilized peat soil, as well. The results of this study indicate that the use of hydrated lime in peat stabilizing obviously can be improved geotechnical properties of these soils. Peat mixed with different percentages of hydrated lime and cured in different time. Unconfined compressive strength test was performed on untreated and treated sample. The stress-strain behavior of lime-stabilized mixes was plotted and the results indicate that the use of hydrated lime in the peaty soils obviously tends to increase the compression strength.

Adaptive neuro-fuzzy inference system (ANFIS) and artificial neural network (ANN) models have been extensively used to predict different soil properties in geotechnical applications. In this study, it was aimed to develop ANFIS and ANN models to predict the unconfined compressive strength (UCS) of compacted soils. For this purpose, 84 soil samples with different grain-size distribution compacted at optimum water content were subjected to the unconfined compressive tests to determine their UCS values. Many of the test results (for 64 samples) were used to train the ANFIS and the ANN models, and the rest of the experimental results (for 20 samples) were used to predict the UCS of compacted samples. To train these models, the clay content, fine silt content, coarse silt content, fine sand content, middle sand content, coarse sand content, and gravel content of the total soil mass were used as input data for these models. The UCS values of compacted soils were output data in these models. The ANFIS model results were compared with those of the ANN model and it was seen that the ANFIS model results were very encouraging. Consequently, the results of this study have important findings indicating reliable and simple prediction tools for the UCS of compacted soils.

This study compares the effects of different hydrated lime contents and curing periods in peat stabilization using unconfined compressive strength (UCS) and consolidated-undrained triax-ial (CU) tests which constitutes the first comprehensive experimental study on peat in Iran. Since it includes a novelty comparison between these tests along with providing experimental data for both test types. For this purpose, lime contents of 3, 6, 9, 12 and 15% were used with different curing periods of 7, 14, 28 and 90 days. The results obtained in these tests were then compared. In order to compare, for triaxial tests, a novelty value of equivalent unconfined strength, which is the strength in case of hypothetical zero confining pressure in a triaxial test, is introduced and calculated and then compared with UCS values. Results indicate that the equivalent unconfined strengths of CU tests are always lower than those of the UCS test which can be attributed to pore water pressure generation in CU tests which can decrease the equivalent unconfined strength of soil. Moreover, while the undrained cohesive strength is half of the UCS value, the undrained cohesive strength is 0.35 times the equivalent unconfined strength for peat. Such comparison between UCS test, which is quite common and easily conductible, and triaxial test, which provides the most comprehensive data in soil mechanics, could lead to credible results which can be widely applicable in forest areas and regions with much vegetation which is the case in northern parts of Iran. Moreover, based on the comparison, the optimum lime content for peat stabilization in this study was obtained between nine and twelve percent.

Current research emphasis is more on the utilization of materials that are considered as waste. Tailings and fly ash are major category of industrial wastes, whose disposal is problematic from environmental point of view. In this present research, Industrial byproducts, namely, lime (CaO) and class F type fly ash have been used as candidate materials along with the partial addition of ordinary Portland cement (OPC) in the Stabilization/solidification (S/S) of polymetallic iron ore mine tailings (TM). The effectiveness of S/S was assessed by comparing laboratory experimental values obtained from unconfined compressive strength (UCS), hydraulic conductivity and leaching propensity tests of S/S samples with regulatory standards for safe surface disposal of such wastes. Some S/S cured matrices were found unable to provide the required immobilization of pollutants. S/S and 28 days cured mine tailing specimens made with composite binders containing TM/10/0/0, TM/5/0/20, TM/10/0/40 and TM/0/10/40 significantly impaired the solubility of all contaminants investigated and proved successful in fixing metals within the matrix, in addition to achieving adequate UCS and hydraulic conductivity values, thus satisfying regulatory norms (U.S. EPA). Laboratory investigations revealed the TM blends (stabilized materials) were non-hazardous. The test results of this study are encouraging and it may be possible to undertake large-scale fill construction with stabilized tailing material that is sustainable and cost effective.

Soil is a base of structure, which actually supports the structure from beneath and distributes the load effectively. If the stability of the soil is not adequate then failure of structure occurs in form of settlement, cracks etc. Expansive soil also known as black cotton soil is more responsible for such situations and this is due to presence of montmorillonite mineral in it, which has ability to undergo large swelling and shrinkage. To overcome this, properties of soil must be improved by artificial means known as 'Soil Stabilization'. It is a technique which improvises one or more soil properties by mechanical, cementing and chemical use. Many research has been conducted for stabilization of soil by using cementing, chemical materials e.g. Fly ash, cement, Calcium chloride, Sodium chloride etc. Toady world is facing serious problem of disposal of agricultural waste. Western Maharashtra is popular for production of sugar cane in large quantity. Sugar factories produces waste after extraction of sugar cane in machines that waste when burnt, the resultant ash is known as 'Bagasse Ash'. It is a fibrous material with presence of silica (SiO 2 ) and can be used to improve the existing properties of black cotton soil. In this study laboratory experiments were conducted on black cotton soil with partial replacement by Bagasse Ash (3%, 6%, 9% and 12%). This paper highlights significant increase in properties of black cotton soil obtained at 6% replacement of Bagasse Ash without any chemical or cementing material.

Expansive soils are causing number of damages to the structures particularly light buildings and pavements compare to other natural hazards like earthquake, floods, etc. Thus, worldwide these soils are considered to be problematic soils and pose several challenges for engineers. So, as to utilize these soils in an effective way, proper treatment to the soil is required. With the same intention, an attempt is made to modify engineering properties of black cotton soils from Nagpur region, Maharashtra, India by using RBI Grade 81 and sodium silicate. Atterberg's limit, Compaction, California Bearing Ratio (C.B.R.), Unconfined Compressive Strength (U.C.S.) tests were carried out on the samples of soil and soil with stabilizers. Curing of samples is done for 7 days, 14 days and 28 days. RBI Grade 81 added to the soil in dry state in percentage (by weight) varying from 2% to 6% and sodium silicate 3% to 6% in solution (molar concentration). Comparisons of these two admixtures are done on the basis of test results obtained.

Soft clay soil can be stabilized by the adding of small percentages, by weight, of sodium silicate, thereby producing an improved construction material and enhancing many of the engineering properties of the soil. In order to explain such improvements, one of the most frequently occurring minerals in clay deposits, namely, kaolinite was subjected to a series of tests. As sodium silicate stabilization is most often used in relation to construction, the tests were chosen with this in mind. As results, addition of 5mol/L sodium silicate showed the highest unconfined compressive strength (UCS) results. However the effect of chemical molarities on UCS become less and less, with longer curing time.

Improvement of the Geotechnical properties<br> of expansive soils by mixing Lime and<br> Polypropylene Fibers is the main<br> concentration of this research. For this<br> research purpose, expansive soil samples were<br> collected from the North-East part of Dhaka.<br> The soil has been proved to be expansive<br> (Plasticity Index, Plastic Limit, Liquid Limit,<br> Swelling Pressure, Swell Index, and Swelling<br> Potential). In this study, polypropylene fibers<br> and lime were used with soil to observe its<br> effect on the strength and swelling properties<br> of expansive soil. The soil sample was<br> formulated with 2.5% to 10% lime by the<br> weight of soil and 2% polypropylene fiber<br> was mixed with soil. Compared with the raw<br> sample with swelling properties of the<br> stabilized samples decreases in the beginning<br> when lime content up to 7.5%, then it<br> i...

Geotechnical engineers face various problems while designing foundation because of clayey soil due to poor bearing capacity and excessive settlement. So, we rectify that with various engineering works but in this project we choose fibers for improving soil parameters, this method is cost-effective and eco-friendly one. The clay sample was collected from Devakottai, Tamil Nadu, and India. Sisal, polypropylene, and hybrid of these two fibers were used for soil stabilization. The sisal fiber was mixed 0 .1%, 0.2%, 0.3% and 0.4% by weight of the soil samples. Similarly, polypropylene fiber was mixed 0.5%, 1%, 1.5% and 2% by weight of the soil samples and hybrid fiber mixed soil samples randomly distributed. The effect of fiber addition on soil stabilization was evaluated by conducting tests such as Atterberg’s limits, Standard Proctor compaction test, Unconfined Compressive strength test, Specific gravity test, and California bearing ratio test.

Improvement of the Geotechnical properties of expansive soils by mixing Lime and Polypropylene Fibers is the main concentration of this research. For this research purpose, expansive soil samples were collected from the NorthEast part of Dhaka. The soil has been proved to be expansive (Plasticity Index, Plastic Limit, Liquid Limit, Swelling Pressure, Swell Index, and Swelling Potential). In this study, polypropylene fibers and lime were used with soil to observe its effect on the strength and swelling properties of expansive soil. The soil sample was formulated with 2.5% to 10% lime by the weight of soil and 2% polypropylene fiber was mixed with soil. Compared with the raw sample with swelling properties of the stabilized samples decreases in the beginning when lime content up to 7.5%, then it increased. Polypropylene fiber was used to reduce the axial and lateral expansion of this soil. The results show that the untrained shear strength and unconfined compressive strength of improved samples with the addition of lime and fiber concentration is substantially higher than the unimproved samples. Whereas, axial compression decreases finally, it may be said that the stabilization of expansive soils with lime and polypropylene fiber could be a practicable method.

Abstract: The object of this paper is to investigate the effect of adding different chloride compounds including (NaCl, CaCl2, and MgCl2) on the engineering properties of silty clay soil.  Various amounts of salts (2%, 4%, 8%) were added to the soil to study the effect of salts on the compaction characteristics, consistency limits and compressive strength.The main findings of this study were that the increase in the percentage of each of the chloride compounds increase the maximum dry density, decrease the optimum moisture content. The liquid limit, plastic limit and plasticity index decreased with the increase in salt content. The unconfined compressive strength increased as the salt content increased.
Keywords: Soil Stabilization, Silty Clay Soil, Consistency Limit, Unconfined Compressive Strength
Title: A Laboratory Evaluation of Stabilization of Salty Clay Soil by Using Chloride Compounds
Author: Tamadher Abood, Mohamed A. S. Mohamed
International Journal of Civil and Structural Engineering Research
ISSN 2348-7607 (Online)
Research Publish Journals

Due to growing environmental awareness, as well as stricter regulations on managing industrial waste, the world is increasingly turning to researching properties of industrial waste and finding solutions on using its valuable component parts so that those might be used as secondary raw material in other industrial branches. Although iron and steel slag is still today considered waste and is categorized in industrial waste catalogues in most countries in the world, it is most definitely not waste, neither by its physical and chemical properties nor according to data on its use as valuable material for different purposes. Moreover, since the earliest times of the discovery and development of processes of iron and other metals production, slag as by-product is used for satisfying diverse human needs, from the production of medicines and agro-technical agents to production of cement and construction element. Considering the specificity of physical and chemical properties of metallurgical slags and a series of possibilities for their use in other industrial branches and in the field of civil constructions, this report demonstrates the possibilities of using iron slag as partial replacement of sand in concrete. Iron and steel making slag are by products of the iron making and steelmaking processes. To date, these types of slag have been widely used in cement and as aggregate for civil works. The report presents an investigation of mechanical and durability properties of concrete by adding iron slag as replacement of sand in various percentages. The results show that the strength properties of concrete increase significantly when sand is partially replaced by iron slag.

This paper reports the results of advanced data analysis involving artificial neural networks for the prediction of the unconfined compressive strength of granite using only two non-destructive test indexes. A data-independent site-independent unbiased database comprising 182 datasets from non-destructive tests reported in the literature was compiled and used to train and develop artificial neural networks for the prediction of the unconfined compressive strength of granite. The results show that the optimum artificial network developed in this research predicts the unconfined compressive strength of weak to very strong granites (20.3-198.15MPa) with less than ±20% deviation from the experimental data for 70% of the specimen and significantly outperforms a number of available models available in the literature. The results also raise interesting questions with regards to the suitability of the Pearson correlation coefficient in assessing the prediction accuracy of models.

Large quantities of sawdust waste are generated daily by the logging and lumbering industries, and their safe disposal is a major concern worldwide, whereas the properties of some lateritic soils make them undesirable for use in engineering construction. This paper presents the results of a laboratory evaluation of the characteristics of lateritic soil (LS) stabilized with sawdust ash (SDA), subjected to British standard light (BSL) compactive effort to determine their index, compaction, unconfined compressive strength (UCS), and California Bearing Ratio (CBR) results. The results of the laboratory tests show that the properties of LS improved when stabilized with SDA. The particle-size distribution improved from poorly graded, sandy, gravelly material for 100% lateritic soil and silty material for 100% SDA to the gradation with 94.9-99.9% coarse aggregates of sand and gravel, described as gravelly sand and sandy gravel material for SDA-stabilized LS. The CBR results obtained from the study show that, using the Nigerian general specifications, the maximum CBRs of 19.4% (soaked for 24 h) and 24.1% (unsoaked) achieved for the mix proportion (70% LS + 30% SDA), which falls under American highway and transportation industry standards, can be used as subgrade material. This research provides results for the evaluation of SDA-stabilized LS as highway construction material, as it is based on CBR determination, a limited parameter that does not provide information concerning all important solicitations that flexible pavement materials are subjected to, even if still used in developing countries. Further work may be encouraged to assess the resilient modulus of this material under cyclic load as well as the assessment of permanent deformation of SDA-stabilized LS.

Sets of nonlinear formulations together with an energy-based damage index (DI) are proposed to model the behavior and quantify the damage of the confined and unconfined concretes under monotonic and cyclic loading. The proposed formulations and DI can be employed in numerical simulations to determine the stresses and the damages to the fibers or the layers within the sections of reinforced concrete (RC) components. To verify the proposed formulations, an adaptive finite element computer program was generated to simulate the RC structures subjected to monotonic and cyclic loading. By comparing the simulated and the experimental test results, on both the full-scale structural members and concrete cylindrical samples, the proposed uniaxial behavior modeling formulations for confined and unconfined concretes under monotonic and cyclic loading, based on an iterative process, were accordingly adjusted, and then validated. The proposed formulations have strong mathematical structures and can readily be adapted to achieve a higher degree of precision by improving the relevant coefficients based on more precise tests. To apply the proposed DI, the stress-strain data of concrete elements is required. It can easily be calculated by using the proposed nonlinear stress-strain models for confined and unconfined concretes in this paper.

Soil stabilization can be done in a number of ways. Chemical stabilization methods are highly effective when compared with mechanical stabilization. But the cost of the chemicals makes the process to be a costly one. The present experimental work studies the feasibility of using textile effluent for the stabilization of black cotton soil. Soil sample taken for the study is highly plastic and requires stabilization. Textile effluent from the local industries is to be disposed after several stages of treatment to minimize the environmental risk. Textile effluent is found to be alkaline and also has the cations that can be utilized in chemical stabilization of clayey soil. Different percentages of textile effluent are added to the soil sample and observations are made for the changes in the properties of soil such as plasticity index, swell index, Unconfined Compressive Strength and California Bearing Ratio. The swelling, plasticity and strength characteristics are considerably increased with addition of effluent. From the observation of geotechnical properties 100% of effluent is observed to be optimum for use in practical purposes. Treatment with effluent is recommended for the improvement of clayey sub grade.

The unconfined compressive strength (UCS) of rocks is an important design parameter in rock engineering and geotechnics, which is required and determined for rock mechanical studies in mining and civil projects. This parameter is usually determined through a laboratory UCS test. Since the preparation of high-quality samples is difficult, expensive and time consuming for laboratory tests, development of predictive models for determining the mechanical properties of rocks seems to be essential in rock engineering. In this study, an attempt was made to develop an artificial neural network (ANN) and multivariable regression analysis (MVRA) models in order to predict UCS of rock surrounding a roadway. For this, a database of laboratory tests was prepared, which includes rock type, Schmidt hardness, density and porosity as input parameters and UCS as output parameter. To make a database (including 93 datasets), different rock samples, ranging from weak to very strong types, are used. To compare the performance of developed models, determination coefficient (R 2 ), variance account for (VAF), mean absolute error (E a ) and mean relative error (E r ) indices between predicted and measured values were calculated. Based on this comparison, it was concluded that performance of the ANN model is considerably better than the MVRA model. Further, a sensitivity analysis shows that rock density and Schmidt hardness were recognized as the most effective parameters, whereas porosity was considered as the least effective input parameter on the ANN model output (UCS) in this study.

This paper represents an investigation on the microstructures of soil stabilised with binary blending using two different types of waste fly ashes. The microanalysis was conducted in order to realise the improvement in the strength of the stabilised soil. The soil used in this study was an intermediate plasticity silty clayey soil with medium organic matter content. FA1 was optimised in a previous study dependant on the unconfined compression strength (UCS) test conducted on specimens of soil treated with various percentages of FA1. The optimum percentage of FA1 was 12% of the dry weight of the soil. In this study, UCS test was conducted on specimens of soft soil treated with 12% of binder produced by binary blending of FA1 and FA2 with different proportions and the specimens were kept for curing at different periods (3, 7, 14, and 28 days) prior to being subjected to UCS testing. Scanning electronic microscopy (SEM) testing was employed to investigate the mechanism of strength improvement in the most remarkable soil-binder mixture. The results showed a significant development in stabilised soil strength. Moreover, the bond building sequences and subsequent changes in the microstructures of the stabilised soil due to the chemical reaction of the added fly ashes were observed.

Four rock types (quartz mica gneiss, schist, quartzite and calc-silicate) located in the Satluj and Alaknanda valleys were used to test whether a Schmidt hammer can be used to distinguish rock surfaces affected by various natural and man-induced processes like manual smoothing of rock surfaces by grindstone, surface weathering, deep weathering, fluvial polishing and blasting during road construction. Surfaces polished by fluvial process yielded the highest Schmidt hammer rebound (R-) values and the blast-affected surfaces yielded the lowest R-values for the same rock type. Variations in R-value also reflect the degree of weathering of the rock surfaces. It has been further observed that, for all the rock types, the strength of relationship between R-values for the treated surfaces (manual smoothing of rock surface by grindstone) and the unconfined compressive strength (UCS) is higher than for the fresh natural surfaces.

Concrete is an ancient material of construction, first used during Roman Empire. Concrete is the second most consumed substance in the world after water. Plastic is a common material which finds its application in day today life. Lack of proper disposal methods for plastic waste is one of the main hazards faced by present the world. Plastic is of man made material and is a stable polymer which is light in weight. The reduction of waste plastic is essential as it creates various environmental problems. This paper deals with the partial replacement of fine aggregate with plastic granules and using a fixed proportion of steel and polypropylene fibers. Experimental program includes two stages. In the first stage fine aggregate is replaced with 4%,8%,12% plastic granules in an M30 grade of concrete and its percentage was optimized and in the second stage, the residual strength of the above mixes were found out by heating the specimens to200 0 c,300 0 c and 400 0 c for one hour duration. Strength parameters studied includes compressive strength, flexural strength, split tensile strength, residual strength.

Sodium bentonite is recognized as a natural pozzolan that can improve the mechanical properties of cemented materials due to its fineness and high content of silica and alumina. When mixed with cement paste in an appropriate amount, it is capable to impart pozzolanic effect which is vital to ensure continuous strength gain of cemented materials. Besides, the fineness of sodium bentonite enables the clay to bring filler effect on cemented materials, thus refining its pore spaces and reinforcing its structures. For stabilization of highly organic soil such as peat, research works that aim to quantify these effects with sodium bentonite as a natural pozzolan are relatively few. This article focuses on laboratory investigation on the application of sodium bentonite to maximize the filler and pozzolanic effects of stabilized peat. The outcome of the laboratory investigation is an optimal mix design of stabilized peat, which can be effectively applied to improve peat in a geological condition of swampy area for highway construction. Other than sodium bentonite, calcium chloride, Portland Composite Cement (PCC) and silica sand were used as additives to stabilize the peat sampled from Sri Nadi village, which is located in the area of Klang, Malaysia. To develop the optimal mix design, specimens of stabilized peat were tested in unconfined compression, direct shear and falling head tests. Both elemental composition and microstructure of the stabilized soil were examined using energy dispersive X-ray (EDX) apparatus and scanning electron microscope (SEM). It was found that test specimen of stabilized peat containing 10% partial replacement of PCC with sodium bentonite has the maximum unconfined compressive strength at 7days of curing in water and under the application of 50kPa initial pressure. Besides peat, the test specimen was formulated with a 300kgm-3 binder dosage and a 596kgm-3 silica sand dosage. At the same mix design, test specimens of stabilized peat have high values of cohesion, high values of angle of internal friction and very low rates of permeability, which are comparable to that of intact clay with a practically impervious drainage characteristic. Also, it was discovered that after testing, the test specimens showed a progressive increase in the direct shear parameters and a continuous decrease in the rate of permeability with increasing curing time in water. In the EDX and SEM analyses, high peaks of calcium, silicon, aluminum and oxide elements, and insignificant pore spaces of the stabilized peat were observed. This proves the existence of cementation products of mainly calcium silicate hydrate (CSH) and calcium aluminate hydrate (CAH) crystals that were responsible to bind the organic and soil particles together to form stabilized peat. © 2012 Elsevier B.V.

http://ac.els-cdn.com/S0013795212003043/1-s2.0-S0013795212003043-main.pdf?_tid=a2053ce6-66e4-11e3-9514-00000aacb361&acdnat=1387261970_2f749daf097c804708e4906fc2c5f939 
http://www.sciencedirect.com/science/article/pii/S0013795212003043

Kayseri Volcanic slag (VC) is a natural material containing soil-sized rock fragments, pozzolanic minerals and volcanic ash formed as a result of explosive volcanic activity. Volcanic slag exists as ready aggregate in nature in the form of conical slag hills or as waste from building foundation excavations. The purpose of this study is to investigate the potential use of volcanic slags, which are found naturally in Kayseri, as a construction material in large volume filling projects and in the base, subbase and various fillings of flexible paved roads, either directly or after being improved with cement. Based on the results obtained, it was concluded that VC is convenient for use in sub-surface and sub-base layers, but it is not suitable and cannot be used in the base layer without improving the soil properties due to its low CBR value. In order to investigate the use of VC in the base layer of roads, uniaxial compressive strength (UCS) and CBR tests were performed by stabilizing with 3% and 5% cement. As the best result, with 5% cement mixture by weight, 7 and 28 days UCS strength of 3.1 MPa and 4.97 MPa were obtained, respectively, and CBR strength was obtained at 108.4% and 148.6%, respectively. These values meet the minimum strength requirement specified in the standards for the base layer. As a result, it has been revealed that the geotechnical properties of volcanic slags, which are readily available in nature, can be improved after stabilizing with 5% cement and can be used as construction material in in base, subbase and various fillings in flexible pavement.

With rapid growth of population, fast urbanization and more construction of highway, buildings and other structures has resulted in reduction of good quality available land. The mechanical behavior of such nature of soil has to be improved by employing stabilization of Black Cotton Soil (BC soil) is studied by using Lime and Sawdust. Black Cotton soils are highly clayey soils (Montmorillonite clay mineral). The moisture changes in Black Cotton soils, compressibility and plasticity nature can be greatly improved with the addition of Lime and Sawdust. This paper includes the evaluation of soil properties like Optimum moisture content, dry density, and strength parameter (California Bearing ratio value). Different quantities of Lime and Sawdust (% by weight) are added to the BC soil and the experiments conducted on these soil mixes. The result shows that the use of Lime and Sawdust increases the California Bearing Ratio values i.e. the strength of soil to a great extent.

Cement-stabilised rammed earth (CSRE) is a popular building material in Australia due to its natural aesthetic, good thermal properties and environmental appeal. However, little work has been done investigating the effect of long term exposure to environmental conditions on its durability. This paper presents a case study investigating the aged properties of material obtained from a 32-year old CSRE wall in Perth, WA. Core samples were obtained for unconfined compressive strength (UCS) testing and compared to results found for 28-day old specimens, manufactured using the same material and nominal compaction regime, to investigate changes in material strength over time. Sample wall sections were also obtained to determine material volume losses due to erosion. Results found for 32-year and 28-day old material are compared taking into account local climate conditions to comment on the suitability of current laboratory methods for predicting degradation of CSRE materials. Loss of strength due to exposure is found to be significant in this study. This result suggests that, when designing for the longevity of exposed CSRE materials, aging strength is an important factor that should not be neglected.

Red mud is an industrial waste material which is obtained from the refining of bauxite into the form of Aluminium oxide called alumina. In the present study for the use of Red mud with Fly Ash in geotechnical application with various percentages of cement were added. Tests like compaction, grain size distribution analysis, unconfined compressive strength, permeability were conducted to study the interaction of Fly Ash , Red mud and cement particles. Unconfined compressive strength were determined for the curing periods  3, 7, 28days with various combinations of  Fly Ash and  Red Mud mixed with various percentages of cement (0, 2, 4, 6, 8, and 10). From the test results it is identified that as the percentage of cement increases compression strength increases and maximum values attained at 28 days curing periods. Hence Flyash- Red mud- cement stabilized material can be used in the Geo technical applications like Embankments and Liners.

The aim of this paper is to evaluate the unconfined compressive strength of cemented peat in comparison to that of untreated peat. A laboratory study on the unconfined compressive strength of cemented peat is important in order to formulate a suitable and economical mix design for stabilized peat columns developed in deep peatland to support highway construction. To characterize the strength behavior of cemented peat, 14 test specimens of different mix designs of the cemented soil were prepared and tested in unconfined compression tests. The results revealed that test specimen with a mix design of 300 kg m-3 binder dosage by mass of wet peat (90 % MASCRETE and 10 %3 kaolinite in composition), 4 % calcium chloride by mass of binder, and 25 % siliceous sand by volume of wet peat gave the highest unconfined compressive strength of 413.0 kPa after 7 curing days in water. Such positive finding was largely attributed to the reactivity of the binder, calcium chloride and siliceous sand with wet peat. Thus, it can be concluded that high strength cemented peat can be produced when the MASCRETE and kaolinite stabilized peat admixture with siliceous sand acting as a filler, was activated by calcium chloride that accelerated the rate of cement hydration in the soil. © 2009, INSInet Publication.

www.ajbasweb.com/ajbas/2009/3850-3856.pdf

Unconfined compression tests are performed in this study to evaluate the effect of matric suction on the strength and the deformation characteristics of dynamically and statically compacted silt soils. In order to estimate the suction stress, the change in suction and the volume change of the soil samples are measured, and the relationship between suction stress and unconfined strength is established. Under different conditions of the initial degree of saturation and the dry density in soils, the relationship between suction and the degree of saturation at failure can be expressed by a unique soil-water characteristic curve. This result shows a similar tendency to that of a predicted equation using the same parameters for the soil-water characteristic curves. The unconfined compressive strength is also affected by the suction stress which seems to work as a confining pressure for unsaturated conditions. These results demonstrate that the suction stress can be used for estimating the relationship between suction and the unconfined compression test.

Static Parameters of soil such as the Static Elastic modulus (E_s) and the
Unconfined Compressive Strength (UCS) are important parameters used to predict the
behavior of soil under static load. However, the tests to obtain such parameters are
time-consuming and destructive. By correlating the static parameters to the dynamic
ones, one can use a nondestructive method such as the ultrasonic test to predict the
needed parameters. This study presents the results of experiments conducted on clayey
soil samples in the aim of investigating possible correlations between their mechanical
properties and ultrasonic pulse velocities of Primary wave and Shear wave. Uniaxial
Compression and ultrasonic tests were carried out on 20 clayey soil samples retrieved
by wash coring from different sites. A regression analysis was done to find the best fit
equations for predicting the static parameters of the tested clay. The obtained equations
provide high correlation coefficients and can be used to predict certain parameters
(modulus of elasticity, shear modulus and unconfined compressive strength) with
acceptable accuracy.

In this paper weathered coal fly ash has been used in polycondensation processes aimed at the production of geopolymer-based low temperature ceramic bricks. The ash has been employed both "as received" and after drying, showing favorable reactivity in any case. Different curing conditions with a variable period at 60 °C have been tested. Samples obtained have been characterized by measuring Unconfined Compressive Strength (UCS) and by SEM observations. Good strength values have been obtained with the systems tested. Furthermore, it has been found that mechanical performance increases as the time during which samples are kept at 60 °C increases.

Recently, ground improvement has become much more feasible. Chemical stabilization is a quick and affordable approach to enhancing soil characteristics. An important avenue of research is discovering alternative materials for use in soil enhancement. Pulverized fuel ash (PFA), which is a waste byproduct of coal power plants, has been shown to reduce the environmental risks and costs involved in construction. In this study, a series of unconfined compressive tests were performed for various mixtures of cement, PFA, and sand; the tests considered both the curing period and the optimum moisture content (OMC). In addition, multiple variable linear regression was used to analyze laboratory data in order to obtain an empirical relationship that can be used to predict the unconfined compressive strength (UCS) of a PFA–cement–sand mixture. The accuracy of the model was verified using statistical indices. The first objective of this study was to assess the effects of PFA content on the UCS of the mixture. The second was to investigate the impact of the OMC on the UCS. The focal point of this study was its derivation of a relationship that can be used to estimate the UCS on the basis of existing variables. The results indicated that PFA can strengthen sand in terms of the UCS and that excessive PFA in a mixture may adversely affect the UCS of a medium. Therefore, a mixture must have an optimum proportion of compounds. The OMC plays a vital role in enhancing UCS. The UCS of different mixtures can be predicted with an acceptable level of accuracy by using the relationship derived in this study.

Studies on microorganisms in soils is necessary for understanding the behaviour of soils and mechanism developing for deciding the nature of the soil. The microorganisms may exist in soil or induced into the soil. These studies are referred to with different names based on the intended purpose. Soil Microbiology encompasses the study of microorganisms and their processes in soil The interaction of organisms with each other and their environments involve Soil Ecology. Soil Biochemistry includes microbial processes, soil enzymes, and the formation and turnover of soil organic matter. Microorganisms/ Microbes are classified as Bacteria and Virus. Most of the Bacteria are useful to humankind and virus have provoking effects on the environment as well as on human beings. At present bacteria is used in several civil engineering applications as listed in recent research work in literature. From the Civil Engineering perspective, When the water content of some soils changes, problems arise in structures resting on swelling soils, mainly the strength of swelling soils decrease drastically. In the present paper chemical stabilization using bacteria is considered to improve the strength and reduce swelling behaviour by mixing different dosages of Bacteria to selected soil and waiting for different curing periods. The methodology is used for induction of microbes into selected soil and inspect the strength, based on the results of Unconfined Compressive Strength(UCS). The mechanism that occurred is analyzed using Scanning Electron Microscope (SEM) studies. Bacteria is isolated from vegetable peel waste and induced to the selected soil for finding variation in the strength of soil so as to ascertain the optimum dosage for bacteria induction and curing time for better strength improvement. The test results show an intensification of the strength of the soil as a result of the process of enzymatic Calcium Carbonates (CaCO3) precipitation.

Recently, ground improvement has become much more feasible. Chemical stabilization is a quick and affordable approach to enhancing soil characteristics. An important avenue of research is discovering alternative materials for use in soil enhancement. Pulverized fuel ash (PFA), which is a waste byproduct of coal power plants, has been shown to reduce the environmental risks and costs involved in construction. In this study, a series of unconfined compressive tests were performed for various mixtures of cement, PFA, and sand; the tests considered both the curing period and the optimum moisture content (OMC). In addition, multiple variable linear regression was used to analyze laboratory data in order to obtain an empirical relationship that can be used to predict the unconfined compressive strength (UCS) of a PFA-cement-sand mixture. The accuracy of the model was verified using statistical indices. The first objective of this study was to assess the effects of PFA content on the UCS of the mixture. The second was to investigate the impact of the OMC on the UCS. The focal point of this study was its derivation of a relationship that can be used to estimate the UCS on the basis of existing variables. The results indicated that PFA can strengthen sand in terms of the UCS and that excessive PFA in a mixture may adversely affect the UCS of a medium. Therefore, a mixture must have an optimum proportion of compounds. The OMC plays a vital role in enhancing UCS. The UCS of different mixtures can be predicted with an acceptable level of accuracy by using the relationship derived in this study.

A study has been undertaken to investigate the strength of stabilized clay-soil reinforced with randomly distributed discrete plastic waste fibers by carrying out unconfined compressive strength and tensile-split strength test. In this study, the clay soil was stabilized with lime and rice husk ash mixtures. The effect of the fiber length and content on the compressive and split tensile strength was investigated. The laboratory investigation results show that inclusion of the plastic waste fiber increased significantly both the unconfined compressive strength and tensile-split strength of the stabilized clay soil. The fiber length plays a significant contribution in increasing the soil strength. To contribute for any significant improvement on compression as well as tensile strength, the fiber length should be in range of 20 mm to 40 mm. Fiber reinforcements also reduced soil brittleness by providing smaller loss of post-peak strength.

One of the main problems in industrial applications is the handling of fine cohesive materials. This cohesion can cause hang-ups in process equipment and stop or slow down processing. Conversely, just a small quantity of cohesion in a bulk powder can prevent particle size segregation. It is obvious that understanding cohesion from a fundamental point of view is useful in describing process flow behavior. Capillary force between particles is one source of cohesion between particles. This paper presents a theory that can be used to model the cohesive behavior of bulk materials based on capillary forces between particles.

It has been a common practice to estimate the Unconfined Compressive strength (UCS) of rock through correlations that relate it to other index parameters such as the Brazilian Tensile Strength (BTS) and the Ultrasonic Pulse Velocity í µí±‰ í µí± ; nonetheless, selecting the most appropriate equation to use has always been a challenge considering the heterogeneity of rocks and their variant behaviour. Therefore, the use of equations which are especially developed for certain rock type at a specific location is recommended. This paper suggests 3 equations to predict UCS from BTS, bulk density (í µí¼Œ) and í µí±‰ í µí± for marlstone of the Eastern Province of Saudi Arabia. 35 core samples are collected and tested in the laboratory for UCS, BTS and í µí±‰ í µí±. Statistical analysis is performed on the experimental results, and subsequently 3 statistical models that relate BTS, í µí±‰ í µí± , and rock bulk density í µí¼Œ to UCS are developed. Corrected correlation coefficients of th...