Soil stabilization

About: Soil stabilization is a research topic. Over the lifetime, 3161 publications have been published within this topic receiving 48437 citations.

Stabilization of weak pavement subgrades using cement kiln dust

Abstract: Clays are notoriously well known for giving rise to swelling problems and difficulties in construction due to excessive settlement and limited strength. Hence, such types of soils need to be stabilized before construction for improving their engineering properties. In soil stabilization, cement is commonly used as a stabilizing agent, to simultaneously increase the strength and stiffness of the originally weak, soft material. However cement is relatively expensive and potentially harmful to the environment when admixed with soils. The need for alternative stabilizing agents which could reduce the use of cement is therefore apparent. The objective of the present study is to investigate shear strength characteristics as well as mechanical strength of Kaolinite clay soil treated with 5, 10, 15, 20 and 25 % by weight of cement kiln dust. This has been done to make the soil suitable to build pavements over it. Standard Proctor tests have been conducted to determine optimum moisture content and maximum dry density of Kaolinite clay and Kaolinite clay stabilized with 5, 10, 15, 20 and 25 % of CKD passing 425 micron IS sieve. It has been observed that with increase in the percentage of cement kiln dust, OMC decreases and MDD increases. The decrease in OMC with increase in cement kiln dust content may be attributed to the addition of material which is classified as silty sand to the parent material. The presence of cement kiln dust having higher specific gravity may be the cause for increase in density. A series of unconfined compressive strength tests have been conducted to determine the strength characteristics of Kaolinite clay treated with various percentages of cement kiln dust. It has been observed that up to 20 % mixing of admixture, unconfined compressive strength (q u) and undrained shear strength (c u) increase significantly then decrease with further increase in percentage of stabilizer. It may be attributed to the addition of non-plastic silty material having free lime content. However, when the same samples were tested for mechanical strength by performing CBR tests, it has been observed that the CBR values increases with increase in percentage of CKD. It may also be attributed to the addition of non-plastic silty material having free lime content. Overall, it has been observed that the cement kiln dust effectively increases strength and hence make clays suitable for building pavements over it.

Effect of RBI-81 on CBR and Swell Behaviour of Expansive Soil

Abstract: Many ground improvement techniques have been evolved in the past decade in order to reduce the potential of severity of the expansive soils. Out of those techniques, soil stabilization is the most effective technique. This paper presents results of the investigation carried out to stabilize an expansive soil using RBI grade 81 stabilizer. Free swell index, CBR and SEM analysis were carried out on both untreated and treated soils. There was a considerable reduction in swell potential and an increase in the strength of the soil with the addition of stabilizer. Stabilization of soil involves the enhancement of soil properties by addition of stabilizer which may be organic or inorganic in nature. Among various ground improvement techniques, soil stabilization is an effective method that enables to re-use the in-situ soil upon application of stabilizer having the potentiality of modifying the existing property of a soil. Generally soils have varying engineering properties that may or may not be suitable for construction. As far as road construction is concerned, cohesive clayey soil is a tough challenge for highway engineers due to its swelling and shrinkage characteristics which are the sole reasons for pavement failures. Stabilization of such Kaolinite and Montmorrillonite soils by means of mechanical or chemical methods helps to re-use the soil instead of road cutting for replacing the in-situ soil with suitable carted earth as subgrade. Conventionally, lime stabilization, bitumen stabilization and cement stabilization were practiced as ground improvement techniques. There are other cementious stabilizers used for soil stabilization in case of soils having very low CBR. Reddy and Moorthy (2004) have shown that pond ash along with small amount of lime when added to poor clayey sub-grade, improves CBR and thereby increases the pavement life and reduces the thickness. In this study RBI grade 81 (Road building international) soil stabilizer is used for improving the soil properties of an A-7-6 (HRB classification) soil. RBI grade 81 is ecofriendly natural inorganic cementious soil stabilizer. Objective of the study deals with the comparison of the strength and microstructural changes of virgin soil sample and RBI grade 81 stabilized soil at various curing days mixed with various dosages i.e., 2%, 4% and 6%. II. Literature Review

Investigation of mobility and bioavailability of arsenic in agricultural soil after treatment by various soil amendments using sequential extraction procedure and multivariate analysis

Abstract: Arsenic (As) partitioning in soil stabilization processes responded differently to various application factors. This research reported on the use of multivariate analysis to assist in the investigation of As partitioning after treatment by various soil amendments. The soil samples were taken from an agricultural area located in a mountainous region of Chiang Mai province in Northern Thailand. The soil amendments were FeSO4, FeCl3, Fe-EDTA and CaCO3 with the application rates of 0 (control), 0.1, 0.5 and 1% w/w. A Sequential Extraction Procedure (SEP), resulting in a total of 8 fractions, was performed on the amended soils to monitor As partitioning. Using the established Partial Least Squares (PLS) model, the distribution pattern of the As partitioning was revealed. It was possible to visualize the stabilization characteristics of the soil amendments. Fe-EDTA had the smallest effect on the soil pH. Notably, CaCO3 possessed the ability to reduce the bioavailability of As; however, it failed to reduce the mobility of the As in the soil. Furthermore, FeSO4 has proven to be the most effective stabilizing agent with regard to the reduction of the bioavailability and mobility of the As in contaminated soil. These findings corresponded to the quantitative results wherein bioavailable As was decreased by up to 60–95% in soil amended with Fe-based amendments, whereas CaCO3 only led to the reduction of 38% when compared with the amount of As in the control soil. In addition, FeSO4 effectively immobilized As with a total increase of 282% for As mobility. However, the degree of As mobility of the soil amended with CaCO3 was not notably different from that of the control soil. The reported procedure is expected to be a new tool for visualizing and predicting the potential effects of the soil amendments in terms of controlling the mobility and bioavailability of As in contaminated agricultural areas.

Forensic Investigation of Pavement Distortions Using Soil Suction

Abstract: State Highway 6 in Brazos County, Tex., is experiencing significant changes in surface profile at several locations. The changes in surface profile were noticed within a few months after construction. They quickly became severe enough to adversely affect vehicle safety. The longitudinal distance between the peak of the undulations is usually greater than 30 m. Patching to maintain a reasonably safe surface profile has been performed at least annually since construction. Routine site investigations prior to construction did not reveal underlying soil conditions that could produce these kinds of pavement distresses that appeared relatively soon after the pavement subgrade was stabilized with lime. In this study, the area was investigated using soil suction profiles to determine the origin(s) of the pavement distresses manifested at the surface. Findings indicated the swells were not caused by lime stabilization of sulfate bearing soils but were the result of surface water flowing through deep cracks and/or permeable soil layers to highly plastic expansive clays. Researchers used soil suction profiles to analyze the problem and recommended remedial measures to reduce subsequent swelling.

Role of Sodium Silicate Additive in Cement-Treated Kuttanad Soil

Abstract: This study aims at understanding various parameters that influence the performance of the sodium silicate (SS) additive along with cement in treating the soft Kuttanad soil. The change in soil structure in the presence of SS additive during cement treatment has been correlated with the engineering properties of cement-treated Kuttanad soil. The unconfined compressive strength (UCS) of samples was measured to study the additive dosage effect and to evaluate the impact of the clay water to cement (W/C) ratio on the additive performance. Microstructural and mineralogical investigations were carried out using X-ray diffraction (XRD) studies, scanning electron microscopy (SEM), pH, and zeta potential measurements. The results show that the presence of SS additive notably impacts the strength behavior of Kuttanad soil treated with cement by more than one mechanism. SS additive accelerates and augments the formation of calcium silicate hydrate (CSH). Further, it is found to induce changes in fabric and pore water chemistry that favor enhanced cementation imparting substantial strength to the cemented soil matrix. (C) 2016 American Society of Civil Engineers.