Showing papers on "Soil stabilization published in 1999"

Effectiveness of Portland Cement and Lime in Stabilizing Clay Soils

Abstract: Pavement subgrades constructed with clay soils can cause significant pavement distress because of moisture-induced volume changes and low subgrade support values. Lime is well known for its ability to stabilize plastic clays; however, portland cement also provides highly effective clay stabilization, usually with the added benefit of higher strength gain. Stabilizing clays with cement or lime can improve subgrade properties at a lower cost than either removing and replacing material or increasing the base thickness to reduce subgrade stress. The clay soil stabilization mechanism for the calcium-based stabilizers portland cement and lime is reviewed. These materials modify soil properties through cation exchange, flocculation and agglomeration, and pozzolanic reaction. Additionally, cement provides hydration products, which increase the strength and support values of the subgrade materials as well as enhance the permanence of the treatment. Comparative laboratory and field performance studies by others, fo...

Use of deep cement mixing to reduce settlements at bridge approaches

Abstract: Differential settlements between a bridge and the backfill behind the abutment have been a major problem in the construction of expressway embankments over a soft clay foundation. Deep cement mixing (DCM) columns with varying lengths were used to reduce such differential settlements along the Fu-Xia Expressway, Fujian Province, China. The performance and the feasibility of the DCM method were investigated in a trial embankment constructed prior to the actual construction. This paper presents the results of the instrumentation including total settlements, multipoint settlements, soil pressures on both the DCM columns and soil surface, pore-water pressures, and lateral movements obtained from in situ monitoring. The strength of the soil-cement from laboratory mix tests and from in situ quality control tests on DCM columns is presented in the paper. Study results indicate that DCM columns with varying lengths were a simple and effective method to reduce the total and differential settlements from a soft clay foundation at a bridge approach.

Soil Stabilization with Sodium Chloride

Abstract: The potential of sodium chloride as a stabilizing agent for highway construction has been investigated. Literature covering laboratory and field studies since the early 1900s is briefly reviewed. The results of laboratory tests with mixtures of several soils and a gravel with a commercial montmorillonite clay stabilized with rock salt and brine are presented. The laboratory study included the Atterberg limits test, compaction test, unconfined compression test, California bearing ratio test, indirect tensile strength test, and cyclic triaxial test. The cyclic triaxial tests were conducted to determine resilient modulus and permanent deformation under cyclic loading as well as Poisson's ratio. The beneficial effects of sodium chloride stabilization are discussed.**The following article published in the Transportation Research Record: Journal of the Transportation Research Board (TRR): Soil Stabilization with Sodium Chloride, published in 1999 in TRR No. 1673 has been retracted due to unacknowledged overlap ...

Field and Laboratory Evaluation of the Use of Lime Fly Ash to Replace Soil Cement as a Base Course

Abstract: The performance of lime and fly ash-stabilized base as an alternative to soil-cement-stabilized base for flexible pavement systems on reconstructed highways in Louisiana is evaluated in this study. Historically Louisiana has used soil cement for most flexible base construction because of its low cost, high compressive strength, and ease of construction. However, soil cement is subject to excessive cracking due to shrinkage, which may decrease the expected pavement life. Lime and fly ash bases exhibit many of the same properties as soil-cement bases with potential for less shrinkage cracking. Lime and fly ash (Class C fly ash) test sections were installed on two Louisiana highway reconstruction projects in the northwestern part of the state. For each project, two 0.4-km (0.25-mi) test sections with different percentages of lime and fly ash were constructed. The remainder of each project was constructed with 8 percent soil-cement base by volume. On both projects, the first test section used 2 percent lime a...

Geotechnical characteristics of fly ash-soil mixtures

Abstract: This paper presents the results of laboratory experimental studies carried out on fly ash-soil mixtures. Two fly ashes, one from Rajghat thermal power station, New Delhi, India, and the other from a chemical manufacturing industry Baumineral near Bochum, Germany, were collected and their physical and chemical characteristics were studied. The fly ashes were mixed with the soils available near their respective areas in different proportions and their geotechnical characteristics were investigated. The laboratory test program included compaction tests, unconfined compression tests, direct shear tests, unconsolidated undrained triaxial shear tests, consolidaiton tests, permeability tests and CBR tests. The results obtained were of similar magnitude and showed comparable characteristics as those reported in the literature on fly ashes from other parts of the world. It might be possible to make a reasonable estimate of the maximum dry unit weight and the optimum moisture content of fly ash-soil mixtures from their specific gravity. (A)

Stabilization of desert sand with cement kiln dust plus chemical additives in desert road construction

Abstract: In desert areas where good material sources are limited, the environment is harsh, and the processing and haulage of conventional good quality materials to the site for pavement layers can be expensive and time-consuming. Alternative methods to use readily available materials, wind-blown sand in this case, should be considered. This paper presents the results of a laboratory investigation into the stabilization of desert sand with cement kiln dust (CKD) for use in road pavement structures. Stabilization of this sand with a waste product, CKD, was achieved, but as large amounts of CKD were needed to meet pavement layer standards, chemical additivies were used to reduce the CKD requirement. Potential additives - sodium metasilicate and calcium chloride - were selected on the basis of reports from earlier studies on sand-cement stabilization. (A)

Field Testing of Stabilized Soil

Abstract: Remediation of a Superfund site in Stratford, Connecticut, involved stabilization of the subgrade with portland cement Part of the remediation site was to be used as a parking area The stabilized soil was to be covered with natural base/subbase course materials and capped with an asphalt concrete cover During the course of the remediation, a base-course layer could not be placed prior to the onset of winter A field study was conducted to quantify any changes in the mechanical properties of the open stabilized subgrade subjected to freeze-thaw cycling during the winter of 1996-1997 Field evaluation was conducted with pavement industry tools: the Clegg impact hammer and the dynamic cone penetrometer Evaluation results show the viability of the Clegg hammer as an instrument for quality assurance and also show that there can be up to 50% loss in compressive strength of the subgrade within the uppermost layer of the material caused by freeze-thaw cycling

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.

Dry mix methods for deep soil stabilization : proceedings of the international conferece on dry mix methods for deep soil stabilization/stockholm/sweden/13-15 october 1999

Abstract: It is a truism that we can no longer freely pick areas with the most suitable ground conditions for building purposes. Soils must often be improved in order to take the loads from buildings, roads and other objects. This volume contains papers covering a range of relevant topics and issues.

Mixed-in-place stabilization of pavement structures with cement and additives

Abstract: The paper describes new developments of mixed-in-place stabilization of (sub-) base courses with cement. This method can be used in road and highway engineering as well as for airport runways. Essential are the mixing capacity of the site equipment, a precise scheduling, and proper suitability and acceptance tests. The minimizing of reflective cracking can be achieved by several methods, whereby micro-crack rolling of the fresh stabilization has proved very effective. This relaxation rolling can be optimized by means of continuous compaction control (CCC). Furthermore, CCC provides complete quality assurance - contrary to conventional random spot checking. The paper also reports on combined stabilizations: cement plus bitumen to minimize reflective cracking and lime plus cement for cohesive soils.

Geotextile reinforcement of low-bearing capacity soils: comparison of two design methods applicable to thawing soils

Abstract: : Thawing fine-grained soils are often saturated and have extremely low bearing capacity. Geosynthetics are used to reinforce unsurfaced roads on weak, saturated soils and therefore are good candidates for use in stabilization of thawing soils. To stabilize the soil, a geotextile is placed on it, then the geotextile is covered with aggregate. Design involves selection of aggregate thickness and geotextile. There are two commonly used design techniques for geotextile reinforcement of low-volume roads, and the Army uses one of them. The theory and use of the two design methods for static loading (i.e., up to 100 vehicle passes) are presented and compared in this report. The design method not used by the Army offers the potential to reduce aggregate thickness over the geotextile because it accounts for the fact that the geotextile helps support the traffic load (when in tension) and confines the soil between the wheels and the subgrade. However, this alternative method appears to be unconservative with respect to stresses estimated at the subgrade surface. Thus, the current Army design technique should be used until more research is conducted. In the meantime, straightforward design curves for Army 10- and 20-ton trucks as well as vehicle loading and tire pressure information for a number of other vehicles are included in this report to help make the current design method easy to use. Future work should consider adopting a hybrid design method that provides realistic estimates of stresses at the subgrade and accounts for the tensile properties of geotextiles.

Pavement materials in road building: guidelines for making better use of local materials

Abstract: Locally available road construction materials, particularly in rural areas, are often of marginal quality. Best performance may not always be achieved due to the often limited technical knowledge of the material being used. The guidelines include information on how soil types perform across Australia with information gathered from practical, local experiences, laboratory soil testing and case studies. Detailed advice is provided about 50 different soil types available across Australia. Maps and references make it easy to locate soil types and climatic information. Simple low cost techniques are described on how to test soils to arrive at a better understanding of a given soil type. Guidance is given on how to best treat a soil for particular use as a sub-base or base course and as a wearing course in the case of unsealed roads. Additionally general advice is provided on stabilisation techniques and calculation of mix blends. Appendices cover pavement design and construction and the Thornthwaite Moisture Index. A comprehensive list of references is included to guide the reader to further information. (a)

Soft soil improvement by mixing with sand or cement

Abstract: Soil improvement by mechanical and chemical stabilization is modeled by laboratory testing clay-sand mixtures and cement-treated sand, respectively. In the first case, the transition from "clayey" into "sandy" behavior was recorded at mixing ratios that depend on soil porosity. In the second case, debonding was investigated with sand containing a small admixture (from 2%) of Portland cement. Sand-clay mixtures may model the behavior of natural clayey-sandy soils while cement treated sand models debonding of natural cemented soils.

Soil-binding agent affinity in soil stabilisation with cement and/or lime

Abstract: The use of lime and/or cement for treating originally unsuitable soils, used in the construction of infrastructural soil works, is a technique which presents a remarkable contribution to the safeguard of environmental wealth. During the preliminary studies for the construction of the Milan-Naples High Speed railroad line, an experimental research, aimed at determining a reliable criterion for both the selection of those soils which should be improved or stabilized, and the choice of the most suitable binding agent for this aim, has been performed. The results achieved are of great scientific and technical interest. The grain size distribution, plasticity, bearing capacity and resistance variations recorded in the soil, both before and after the addition of the binding agent, have shown the different affinity of soils towards various binding agents and the important influence of the mineralogical composition.

Six rows of high capacity removable anchors support soil mix cofferdam

Abstract: The use of high capacity soil anchors in lieu of internal props to support the cofferdam walls allowed rapid bottom-up construction of new rail tunnels with unimpeded progress. Innovative techniques in the use of a 38 m (124 ft) deep soil mix wall and 200 kN working capacity fully removable anchors were utilized.

Effects of fly ash admixture on the mechanical behaviour of silty clay

Abstract: The significant part of the electrical power in Turkey is produced in coal consuming thermal plants. About 15 million tons of fly ash is produced as by-product while the annual total cement production is about 25 million tons. As with other industrial wastes, it leads to stocking and environmental problems. Low cost availability and chemical properties of fly ash give opportunity to look for opportunities in the geotechnical engineering field and to minimize the hazard to the environment. In this paper, the effect of the fly ash admixture on the strength of silty clay has been experimentally investigated and the possibility of using fly ash in road construction is discussed.

Geotechnics of the austrian-hungarian highway a4

Abstract: The Austrian-Hungarian Highway A4 runs through a region with extremely heterogeneously geological conditions. Consequently, extensive soil exchanges and a careful separation of suitable material according to its re-use was necessary. Comprehensive testing was required in order to select frost resistant material for the sub-base and suitable material for cement stabilization mixed in place. The cement content had to be determined separately for different materials in order to achieve constant strength parameters. Controls and acceptance testing were performed both with conventional spot tests and roller integrated continuous compaction control with a vibratory roller. The work-integrated method provided an improved quality, and weak spots could be detected and repaired immediately.

Swelling behaviour of stabilized soils

Abstract: Soil deposits stabilized with waste materials - wood-ash and organic mater (leaves, grass, etc) exist in black cotton soil areas in North Karnataka. The wood-ash modified BC soils are apparently stabilized by hydrated lime produced by biochemical, dissolution and hydration reactions. The influence of cyclic wetting and drying on the swelling behaviour of wood-ash modified black cotton soil (BCS) and a laboratory stabilized black cotton (BC) soil are examined in this study. The laboratory stabilized BC soils were stabilized using 2 to 7% (on weight basis) hydrated lime. The study was required to assess the long-term behaviour of earth structures and foundations on stabilized soils. Experimental results showed that chemical stabilization controlled the wetting induced volume changes of the ash-modified soil specimens and laboratory stabilized BCS specimens in the compacted state. Cyclic wetting and drying however caused the ash-modified soil specimens to collapse significantly at the experimental pressures. Experimental results with laboratory stabilized BCS specimens indicated that if a soil is stabilized with inadequate lime content, then the beneficiary effect of lime stabilization is lost on cyclic wetting and drying. (A) For the covering abstract see ITRD E105041.

Extensive mixed in place soil improvement for the botlekspoortunnel

Abstract: A large percentage of the Botlek rail tunnel under the Oude Maas is being bored using an EPB shield boring machine. Part of the route passes through saturated, soft, peat and clay layers. These layers were considered too weak to support a bored tunnel. Large scale soil improvement is to be carried out, mixing the existing soil with cement and possibly with additives. Full scale field trials were carried out beforehand, using various mortars and two techniques - one dry, one wet. Design aspects and the tests are discussed.

Comparison of effectiveness and economic feasibility of bitumen, lime and cement as stabilising agents for reduction of swell potential of a clayey soil

Abstract: The excessive heave, settlement, low shear strength, and internal erosion of some soils may damage engineering structures in the following cases: (1) footings founded on expansive or collapsible soils; (2) roads and runways constructed on an expansive or collapsible subgrade; and (3) earth dams constructed from erodible soil. To avoid such damage, it may help to stabilise the natural soil using appropriate agents. 'Soil stabilisation' is any combination of physical, chemical, and biological methods to improve certain properties of natural soils so that an intended purpose can be served. Bitumen, lime, and cement are possible stabilising materials. This paper presents research to compare the effectiveness and economic feasibility of bitumen, lime, and cement as stabilising agents for reducing the swell potential of a clayey soil. A laboratory testing programme was conducted on a swelling soil from Northern Jordan. Mixtures of soil with these materials were prepared at concentrations of 3%, 6%, and 9% by dry weight of soil. The paper describes the properties of the soils used, sample preparation and testing, the swelling test, and the results of the tests. For soils with a high fines content, bitumen reduced swell potential more than cement and less than lime, but was the least economical stabilising material.

Liquefaction Failure and Remediation: King Harbor Redondo Beach, California

Abstract: A discussion of a paper with the aforementioned title by S.T. Kerwin and J.J. Stone, published in this journal (Volume 123, Number 8, August 1997), is presented. The discussion is directed at the authors' use of Seed and Booker's (1977) design charts for evaluating the secondary benefits of drainage provided by the stone columns at Redondo Beach King Harbor during the 1994 Northridge earthquake. The discussion concludes that the drainage capacity of stone columns or gravel drains during earthquake shaking is strongly affected by the drain resistance and suggests that the importance of drainage for the remedial work at Redondo Beach needs to be carefully reevaluated by the authors, taking the effects of drain resistance into account.