Problematic soils, especially clayey soil, are problematic for engineering projects in their natural state because of clay's swell-shrinkage phenomenon. Numerous methods and stabilizer materials have been used to enhance clay's geotechnical properties and make them appropriate for construction. One of the significant methods of stabilization of problematic soil is using waste materials like waste glass, waste stone, waste plastic, etc. Due to the waste stone's consistency reducing water content and increasing the soil's strength, it has been employed in many civil engineering studies. Waste stone is available in various forms, including waste stone powder (WSP). WSP is produced by blasting tunnels or cutting huge stone blocks. Hence, the main aim of this study is to review the influence of WSP on improving the geotechnical properties of problematic soils treated with WSP, for this purpose, the treated problematic soils with various percentages of WSP are compared with natural soils. This study evaluates physical properties (i.e., Index properties, linear shrinkage/swelling, optimum moisture content, and maximum dry density) and mechanical properties (i.e., unconfined compressive strength and California bearing ratio). Also, the effect of WSP on decreasing the thickness of pavement layers was reviewed
Determinations of unsaturated soil parameters using experimental procedures are time consuming and difficult. In recent years, the soil–water characteristic curve (SWCC) has become an important tool in the interpretation of the engineering behavior of unsaturated soils. Difficulties associated with determining such parameters have justified the use of indirect determination. This paper presents the general nature of the SWCC for soils with different plasticity limits, index and gradation, in terms of gravimetric water content and degree of saturation versus soil matric suction from Anbar governorate. In order to investigate possible relationships between the plasticity limits, index, percent passing no.200 and SWCC, 7 type of soils were tested to find its SWCC experimentally and compared the result with the curves obtained from different model presented in the literature. The objectives of the paper were to check the validity of these models with the experimental results. The results shows a good agreement and to present a simple method for inferring the SWCC for soils, taking into account the liquid limit, plastic limit, plasticity index and percent of fines passing sieve no.200.
Water treatment sludge (WTS) is a byproduct generated during the treatment of wastewater. In recent years, researchers have explored the potential of using WTS as a soil stabilizer to improve the geotechnical properties of soils. In this review, we will examine the current state of knowledge on the use of WTS for this purpose. The organic matter content of WTS is usually high and can range from 30% to 60%. The high organic matter content makes WTS a potential source of nutrients for plants, and it can also enhance soil structure and water retention. Another important consideration is the environmental impact of using WTS. The use of WTS can be an eco-friendly alternative to chemical stabilizers, which can have adverse effects on the environment. However, there are concerns about the potential for heavy metal contamination in WTS. To mitigate this risk, it is recommended to conduct thorough testing of WTS before using it as a soil stabilizer. Finally, the use of WTS as a soil stabilizer has the potential to improve the geotechnical properties of soils. However, it is essential to consider factors such as the type and dosage of WTS, the soil type, and the environmental impact before using it. Further research is also needed to explore the potential of using WTS in different soil types and environmental conditions.
The focusing in this study was on the contaminated-uncontaminated soils' properties whichstudied by performing experimental tests included, Atterberg’s limit, specific gravity, compaction,unconfined compression, and direct shear tests. Different % of crude oil was used in thecontaminated soils which are performed by mixing the soils using different percent of were oilof 3 %, 6 % and 9 % by dry weight. The main effect of oil contamination causes a reduction in theliquid and plastic limit values for clayey soil. Besides oil contamination gives a reduction in themaximum dry unit weight as well as a decreasing the optimum water content with comparisonto original soil (clayey and sandy soil). The angle of internal friction is decreased for sand whileit increases for clay is one of oil contamination results.
The studying of the distribution of wetting patterns in soils having a stratified profile is of great importance due to the presence of this type of profile in abundance in agricultural lands, including greenhouses. Therefore, there was a need to develop a numerical program that predicts the dimensions of the wet area of the subsurface drip irrigation system under different operating conditions for purpose design and manage these systems properly to avoid water losses resulting from evaporation or deep penetration. The present study aims to develop a two-dimension model simulates the wetting pattern in stratified soils using (HYDRUS-2D) software and study the effect of soil hydraulic properties and different operating conditions on the progress of the wetness pattern and the interference pattern between two wetting fronts. Laboratory experiments were carried out for the system of subsurface drip irrigation in stratified soils that consisted of three layers (silty clay loam soil, loamy sand soil, and sand soil) arranged from bottom to up. Three different emitter flow rates 0.5, 1, and 2 l/h were tested, as well as three different initial moisture contents for each soil layer were considered. The interference pattern between two wetting fronts of two emitters with different spacing between emitters 30, 40, and 50 cm was studied. A numerical model was developed to guess the horizontal and vertical dimensions of the wetting zone for the single emitter and the pattern of interference between the two wetting fronts of two emitters. The predicted values obtained from the numerical model were compared with those obtained from laboratory experiments. Statistical analysis of the obtained data showed that the developed numerical model has a good ability to guess the dimensions of the wet pattern of the single and the two emitters and there were good agreements between the predicted and the experiments results and minimum values of RMSE ranged between 0. 5 and 3.6 were achieved.
Deep mixing technology is used to improve the engineering properties of soil. In this review, previous studies on the properties and problems of weak soils were collected and explained, focusing on silty soils found globally and locally. The study also includes a discussion of physical and chemical improvement methods, specifically (cement columns). The advantages of deep mixing technology are also covered from an engineering and economic point of view, as well as its relationship to the environmental impact, as it is one of the sustainable development techniques due to its use of environmentally friendly materials. In addition, one of the objectives of this research is to study the methods of adding cement, whether in the form of powder (dry method) or mortar (wet method). A comparison was made between them to clarify the advantages and disadvantages. It was found that what distinguishes the use of the dry method from the wet method is that the former is more common. The method's effectiveness depends on the soil's moisture content, so the technique is ineffective in soils with less than 30% water content. As cement hydration produces a cementitious gel (CSH) that binds soil particles together, leading to early strength gain, pozzolanic reactions cause increased shear strength and decreased soil compressibility. Finally, some recommendations are included in this article to understand the behavior of cement columns in improving soil and avoiding problems
In this study the effect of sodium hydroxide on the strength of clayey soil-cement mixtures was investigated. Clay soils from three various locations of Kirkuk governorate namely Erbil, Laylan and Hawija check points were used. The effect of cement content, curing age, curing temperature and concentration of sodium hydroxide on the strength of soil-cement mixtures were investigated, through carrying out unconfined compressive strength, Triaxial compression and C.B.R tests. It was found that the use of sodium hydroxide markedly improves the strength of soil-cement mixtures. The addition of about 1% of sodium hydroxide by weight of soil could reduce about 5% of cement content by weight of soil required to stabilize the soils effectively.
Concrete structures suffer from the impact of many harmful attacking materials that affect theproperties of the main material in them, which is concrete. These structures are also, exposedto the negative impact of many hostile environments such as soils containing harmful salts andharmful acids. A number of precautions should be considered in order to protect the concreteused in such structures. Adding polymer to concrete components as a percentages weight ofcement is one of the methods for producing polymer-modified concrete, which has lowpermeability, better mechanical properties and is more resistant to the negative effects ofharmful environmental factors. The utilization of polymers could help in protecting structuresand enhancing concrete strength. In this study, concrete mixes were prepared with inclusion ofstyrene butadiene rubber (SBR) polymer at four percentages (0%, 5%, 7% and 10% by cementweight). Co-polymers of butidine with styrene (styrene-butadine rubber (SBR)), are a group oflarge-volume synthetic rubbers. High adhesion occurs between the polymer films that formand cement hydrates. This action gives improves the properties of concrete such as flexuraland compressive strength and gives also a higher durability. The investigation was extended toevaluate the compressive strength of the SBR concrete mixes immersed in three types ofwaters: tap, drainage and ground water, at three different ages. The results showed that SBRpolymer enhanced the compressive strength of concrete significantly. A comparison betweenreduction in strength of concretes immersed in these three types of waters was also presented.Moreover, the presence of SBR polymer led to reduced loss in strength of concrete specimensimmersed in drainage and ground water. A proposed model to determine the compressivestrength of concrete specimens immersed in drainage and ground waters was deduced. Thismodel could be a helpful tool for rapid and easy estimation of the strength of concretespecimens immersed in drainage and ground water at different contents of SBR polymer. Theresults showed the highest improve in compressive strength to be associated with 7% SBRmixes at the three tested ages. The increases in this strength at days 7, 28 and 56 with inclusionof 7% SBR polymer were 112.8%, 113.9% and 116%, respectively, compared to OPC mix.
The construction of pavement layers on subgrade soil with good characteristics decreases the thickness of these layers, which in turn lowers the cost of building and maintaining roadways. However, it is impossible to avoid constructing pavements on unsuitable subgrade due to a number of limitations. Using conventional additives like lime and cement to improve subgrade properties results in additional costs. As a result, utilizing by-products (cement kiln dust and reclaimed asphalt pavement) in this field has benefits for the environment, economy, and technology. Large amounts of cement kiln dust (CKD), a by-product material, are produced in Portland cement factories. On the other hand, large amounts of reclaimed asphalt pavement (RAP) are accumulated as a result of the rehabilitation of old roads. This paper discusses using CKD and RAP to improve the characteristics of poor subgrade layers by conducting a series of Unconfined Compressive Strength (UCS) and California Bearing Ratio (CBR) tests on samples of natural soil and soil stabilized with different percentages of CKD and RAP with different curing times to investigate their impacts on soil properties. The curing was carried out by wrapping the stabilized samples with several layers of nylon and then placing them in plastic bags at room temperature. The compaction results illustrated that the addition of CKD increases OMC and decreases MDD, in contrast to RAP, which decreases OMC and increases MDD. The addition of CKD and RAP led to a significant and unexpected increase in the CBR values. The results show that the soaked and unsoaked CBR values improve from 3.4% and 12.1% for natural soil to 220.1% and 211%, respectively, after adding 20% CKD and curing the samples for 28 days. Also, the addition of 25% RAP to soil-20% CKD blend increased the soaked and unsoaked CBR values to 251% and 215%, respectively. All the additions resulted in a significant reduction in swelling.