The in-situ deep mixing technique has been established as a means to effect columnar inclusions into soft ground to enhance the bearing capacity and reduce settlement. Since the inception of this method, developments in the plant and machinery, as well as associated field techniques, have surpassed the basic understanding of strength developments in high water-content clays admixed with cementing agents.In this paper an attempt is made to identify the critical factors governing the engineering behavior of cement-stabilized clay, which helps not only to control the input of cementing agent to attain strength development with curing time and clay water content, but also to understand the subsequent engineering behavior. It is revealed that the clay-water/cement ratio, $wc/ c$ is the prime parameter for the above purposes .

Engineering Behavior of Cement Stabilized Clay at High Water Content (IS-YOKOHAMA 2000「沿岸域の地盤工学における理論と実際」特集号〔英文〕)

Red mud is highly alkaline slurry produced during alumina extraction from bauxite. Its disposal generates serious environmental pollution. The best way to solve red mud disposal issues is to develop economic utilization technologies that consume significant amounts of red mud. This paper reviews the possibility of utilizing red mud as a road base material, weak subgrade soil stabilizer as well as a subgrade material. Results showed that red mud can be used for those purposes. It was also found that the stabilizing content needed to meet a certain standard differs due to differences in requirements from one country to another. Therefore, there is a need to design proportions with UCS, CBR, leaching characteristics required by the country in which red mud is intended for use. The effect of various stabilizers on performance of red mud is discussed and it transpired that lime showed the best performance followed by dolime fine, ground granulated blast furnace slag, cement kiln dust and fly ash. Findings indicated that red mud shows better performance as a subgrade material than natural soil. Also the synergistic use of red mud and other wastes also improves the mechanical and durability properties of the material compared with using red mud alone. Based on mechanical, economic and environmental benefits, it is recommended to use red mud in road base structure rather than in subgrade despite higher red mud consumption in subgrade than in road base. The scope for future research in this area is also suggested.

Utilization of red mud in road base and subgrade materials: A review

Foundations on Expansive soils

The Department of Civil and Environmental Engineering offers a minor program in Geotechnical Engineering. Geotechnical Engineering is traditionally an interdisciplinary field, drawing on elements of geology, geophysics, and the mechanics of fluids and solids. This breadth can be obtained by combining an undergraduate major in physical and mathematical sciences with a minor in Geotechnical Engineering. This minor is suitable for students interested in either professional practice or in graduate studies within the Department of Civil and Environmental Engineering at Berkeley, and elsewhere.

Geotechnical engineering - i

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The Foundation Engineering Handbook

The performance of pavement is very responsive to the characteristics of the soil subgrade. For that reason, weak subgrade is enhanced by adopting the most efficient stabilization technique. Based on the literature review, stabilization with fly ash activated with cement was found to be an effective option for improvement of soil properties. In this regard an experimental program was undertaken to study the effect caused by the combined action of fly ash and cement stabilization on the geotechnical characteristics of expansive subgrade soils. Expansive soil treated with varying percentages of fly ash, 0, 5, 10, 15, and 20 percent combined with 5% cement content were studied. Consistency limits, compaction, California Bearing Ratio, swell potential and swell pressure tests were conducted on treated and untreated soils. The experimental results show that addition of cement-fly ash admixture to the soil has great influence on its properties. It was found that the optimum dosage of fly ash is 15% mixed with 5% cement revealed in significant improvement in strength and durability and reduction in swelling and plasticity properties of the soil. Based on the results, it is recommended that cement-fly ash admixture be considered a viable option for the stabilization of expansive subgrades.

/pdf/stabilization-of-pavement-subgrade-by-using-fly-ash-3s0e71pvps.pdf

Stabilization of Pavement Subgrade by Using Fly Ash Activated by Cement

Steel slag is a by-product of the steel industry and can be used potentially as aggregate in asphalt mixture. This study evaluates the use of Steel Slag Aggregates (SSA) as substitute for natural aggregates in the production of hot mix asphalt (HMA) for road construction. Based on intensive laboratory testing program, the characteristic properties of SSA were assessed to determine its suitability to be used in HMA. Four different percentages (0, 50, 75 and 100%) of SSA were used, and the proposed mix designs for HMA were conducted in accordance with Marshall mix design. The experiments results revealed that the addition of SSA has significant improvement on the properties of HMA. An increase in density and stability and a reduction in flow and air voids values were clearly observed in specimens prepared with 100% SSA. It is concluded that the steel slag can be considered reasonable alternative source of aggregate for concrete asphalt mixture production.

Experimental Study of Steel Slag Used as Aggregate in Asphalt Mixture

/pdf/prediction-of-in-situ-cbr-of-subgrade-cohesive-soils-from-97tveyewse.pdf

Prediction of In-situ CBR of Subgrade Cohesive Soils from Dynamic Cone Penetrometer and Soil Properties

The Swelling tendencies of expansive soils are quantified by the swelling potential and/or free swell. Swelling potential or volume change is defined as the ratio of increase in thickness to the initial thickness of the soil sample compacted at optimum moisture content in a consolidation ring and soaked under a token surcharge of 6.9 k Pa, Seed et al. (1962) so that the sample undergoes free swell.

/pdf/swelling-potential-of-compacted-expansive-soils-j8jmcfx9tn.pdf

Swelling Potential of Compacted Expansive Soils

This paper investigates the improvements in the properties of expansive soils, as road subgrade stabilized with lime and fly ash in varying percentages. Laboratory tests were undertaken to study the swelling and strength characteristics of expansive soils stabilized with lime, fly ash and a combination of both. Lime and fly ash were added separately to expansive soil at ranges 0-15% and 040%, respectively. Index property, compaction, California Bearing Ratio (CBR), Unconfined Compression Strength (UCS), free swell and swelling pressure tests were performed on natural and treated soil samples. For the investigated admixture lime-fly ash; the amount of lime added 5% and 8% combined with the fly ash content 0%, 5% and 10%. Comparing the results obtained of the natural and treated samples, the CBR and UCS of lime-fly ash treated samples increased significantly, coupled with the swelling reduction, depending on additive content. It could be concluded that stabilization of expansive subgrade soils by lime-fly ash admixture is successful and more economical.

https://www.ijsr.net/archive/v3i12/U1VCMTQ2MDg=.pdf

Magdi M. E. Zumrawi

Papers

Stabilization of Pavement Subgrade by Using Fly Ash Activated by Cement

Experimental Study of Steel Slag Used as Aggregate in Asphalt Mixture

Prediction of In-situ CBR of Subgrade Cohesive Soils from Dynamic Cone Penetrometer and Soil Properties

Swelling Potential of Compacted Expansive Soils

Improving the Characteristics of Expansive Subgrade Soils Using Lime and Fly Ash