Stabilization of Expansive Soil with Cement Kiln Dust and RBI Grade 81 at Subgrade Level

The present research work deals with an expansive high plastic clayey soil with cement kiln dust (CKD) and stabilizer (RBI Grade 81). The physical and engineering properties of soil are plasticity, compaction, unconfined compressive strength (UCS), consolidation and California bearing ratio (CBR) of the clayey soil and clay treated with CKD and stabilizer were determined. Soil chemistry was examined before and after treatment using scanning electron microscope (SEM) and elemental dispersive spectrometer. The clay mixed with CKD, CKD and RBI Grade 81 was found that optimum contents are 10 % (CKD), 15 % CKD with 4 % RBI Grade 81, respectively. The result indicates that CKD alone will decrease maximum dry density and increase optimum moisture content. CKD with RBI Grade 81 slightly increases maximum dry density and decreases optimum moisture content. UCS increased with CKD alone and CKD with RBI Grade 81 from 88.3 to 976 kN/m², respectively. CBR values were increased by the addition of CKD, CKD with RBI Grade 81 from 1.65 to 21.7 %. With the curing time of 3, 14 and 28 days, UCS and CBR values were increased due to pozzolanic reaction from cementations material. The treated soil has considerable reduction in compression index. SEM images clearly indicate the formation of CSH and CAH gel.     

Assessment of Ornamental Stone Waste as Expansive Soil Stabilizer

This work aims to assessment of the calcitic ornamental stone waste for the stabilization of expansive soil. Calcitic rock-derived waste together with different expansive soils from Egypt were characterized and processed for stabilizer optimization. The mineral, chemical and engineering characteristics of the waste and the soil samples were examined using XRD, DTA, TGA, SEM, XRF as well as geotechnical characteristics such as liquid, plastic and shrinkage limits, plasticity index, free swelling, and uni-axial compressive strength, respectively. The calcitic waste has been calcined in an electrical muffle furnace at 1000℃ for 1 hour. The samples were treated by 0–8% waste post calcination for soaking time1– 4 weeks.     

Analysis of Flexible Pavements Reinforced with Geogrids

Effectiveness of glass fiber grids as a reinforcement of the asphalt layer in a flexible pavement system was investigated. The study involved both laboratory experimental work and computer analysis of pavement sections. Twenty flexible pavement sections (with and without glass fiber grids) were constructed and tested in the laboratory as a part of the experimental study. The laboratory-scale pavement sections were instrumented with pressure cells, displacement gages, and strain gages. Test sections were subjected to 1,000,000 load applications at a frequency of 1.2 Hz. Static loading tests were conducted at intervals of 100,000 load applications. In thirteen experiments, glass fiber grids were used as reinforcement in the asphalt layer. Several computer analyses of flexible pavement sections were performed by using the finite element method (FEM). The laboratory data were compared with results obtained from the computer analyses. Results from this study show that glass fiber grids can be used to improve the performance of flexible pavement systems. It was also observed that the inclusion of glass fiber grid in the asphalt layer provided resistance to crack propagation. Overall, the flexible pavement sections reinforced with glass fiber grids showed better performance under laboratory test conditions.     

Use of Cement Kiln Dust on the Engineering Modification of Soil Materials,Nile Delta,Egypt

Cement kiln dust (CKD) is the by-product generated from the manufacture of Portland cement. Disposal quantities of CKD in construction project are required to protect the environment. In the recent construction experience in the area of study at the last years showed that, ground and underground engineering on the soft soil are susceptible to various types of cracking in buildings and roads. The improvement of engineering properties of two disturbed soils by using CKD in different percentages (5, 10 and 20 %) was discussed in this paper. The results indicated that CKD additives increased the pH values and decreased the plasticity index in both types of soils under investigation. The maximum dry density (MDD) decreased and optimum moisture content (OMC) increased with increasing the percentage of CKD in soil A. In soil B the MDD and OMC decreased.     

膨胀土胀缩特性试验研究

以南(宁)友(谊关)膨胀土大量的室内试验为基础,研究了膨胀土胀缩时程曲线特征,寻找膨胀土膨胀和收缩曲线的异同点,探求了土的初始含水量、干密度与膨胀变形量的定量关系等。     

Assessment of Lateritic Gravelled Materials for Use in Road Pavements in Cameroon

Geotechnical and Geological Engineering - Early surface and structural deterioration of new pavements are becoming increasingly perceptible in Cameroon. This raises serious concerns regarding the...     

Potential Application of Lateritic Soil Stabilized with Cement Kiln Dust (CKD) as Liner in Waste Containment Structures

This study evaluates the applicability of residually derived lateritic soil stabilized with cement kiln dust (CKD), a waste product from the cement manufacturing process as liner in waste repositories. Lateritic soil sample mixed with 0–16 % CKD (by dry weight of the soil) was compacted with the British Standard Light, West African Standard and British Standard Heavy compaction efforts at water contents ranging from the dry to wet of optimum moistures. Geotechnical parameters such as Atterberg limits, compaction characteristics, hydraulic conductivity, unconfined compressive strength and volumetric shrinkage strain were determined. Results indicate that the plasticity index, the maximum dry unit weight and hydraulic conductivity together with the volumetric shrinkage decreased with increased amount of CKD while the optimum moisture content and unconfined compressive strength increased with higher CKD content for all the efforts. When measured properties were compared with standard specifications adopted by most environmental regulatory agencies for the construction of barrier systems in waste containment structures, the resulting values showed substantial compliance. Besides developing an economically sustainable liner material, the present study demonstrated effective utilization of an industrial by-product otherwise considered as waste by the producers, in addition to a systematic expansion in the use of the lateritic soil for geotechnical works.     

Assessing Stabilization Effectiveness of Combined Cement Kiln Dust and Quarry Fines on Pavement Subgrades Dominated by Black Cotton Soil

In developing technically viable and economically sustainable methods of improving soil properties to suit the requirements of engineering structures, designers/engineers are to take into consideration the availability and cost effectiveness of materials required for such improvement scheme. In line with this, the present study evaluates stabilization effectiveness of combined quarry fines (QF) and cement kiln dust (CKD) on subgrades dominated by black cotton soil (BC soil). The experimental programme included Atterberg limits, compaction and California bearing ratio (CBR) tests on soil mixtures prepared with a representative BC soil at constant dosage of 10 % QF and 0, 4, 8, 12 and 16 % CKD. Prior to testing, soil mixtures for CBR test prepared at optimum moistures and compacted with British standard light compaction effort were soaked for 96 h after curing for 28 days. Test data show that the addition of QF and CKD together reduced the plasticity index that resulted in rapid textural changes and eventual improvement in constructability, led to an increase in the optimum moisture content and a decrease in the maximum dry unit weight. Furthermore, the coupled effects of QF and CKD resulted in substantial increase in CBR strength of the composite specimens. Overall, mixtures created using the proposed QF and CKD ratios rendered the soil physically and mechanically stable producing results that are compatible with desired values for engineering performance typically required by various user agencies for pavement subgrades. This improvement scheme is not only cost effective, but it is capable of lessening the demand on non renewable resources thereby reducing the footprint of road construction projects in the environment.     

Optimization of Multi-additives for Expansive Soil Improvement Using Response Surface Methodology

Geotechnical and Geological Engineering - Central composite design, a type of response surface methodology (RSM), was combined with Derringer and Suich desirability function approach (DFA) in this...     

高速公路膨胀土路基改良的试验和分析

对膨胀土路基填料存在问题进行探讨分析。以广东某高速公路为例，对比了膨胀土路基填料改良的试验方法及其效果，提出了掺石灰和粉煤灰等方案的最佳选用建议。试验分析表明，对膨胀土改良的测试和评价不宜采用单一方法，应根据膨胀土的胀缩等级、地方材料及施工工艺等进行综合技术与经济比较，选定最优方案。     

合肥地区膨胀土注浆试验研究

针对合肥地区膨胀土进行劈裂注浆试验 ,分析了注浆及复合土体形成的过程 ;对注浆后形成的复合土体进行三轴固结排水剪试验 ,结果表明经注浆后土体的强度得到显著改善 ,同时 ,复合土体应力应变关系仍符合邓肯模型规律。     

Effect of Lime Stabilized Soil Cushion on Strength Behaviour of Expansive Soil

An experimental investigation was undertaken to study the effects of lime-stabilized soil-cushion on the strength behavior of expansive soil. In the present investigation, a series of laboratory tests (Unconfined compression tests and CBR tests) were conducted on both expansive soil alone and expansive soil cushioned with lime-stabilized non-expansive cohesive soil. Lime contents of 2, 4, 6, 8 and 10% by dry weight of cohesive non-swelling soil was used in the stabilized soil cushion. Both expansive soil and lime stabilized soil cushion were compacted to Standard Proctor’s optimum condition with thickness ratio 2:1. Tests on cushioned expansive soils were conducted at different curing and soaking periods i.e., 7, 14, 28 and 56 days. The test results revealed that maximum increase in strength was achieved after 14 days of curing or soaking period with 8% of lime content.     

Engineering Properties of Cement Kiln Dust-Modified Soils in Western Washington State

The Portland cement manufacturing process produces considerable amount of cement kiln dust (CKD). While many facilities are able to reuse a significant portion of CKD in their production lines, a large percentage is removed as industrial waste and placed in landfills. Because of the large amount of material potentially available for use, and in an effort to cut disposal costs, alternative and beneficial uses for CKD need to be investigated. This study presents experimental results of the use of CKD in modification and stabilization of soils from the Aberdeen and Everett areas in the state of Washington. These soils are typically wet of the optimum water content and pose problems during geotechnical construction. CKD was added in percentages of 5, 10, 15, and 20% by dry weight of the soils. Laboratory tests, including drying rate of the soils, Atterberg limits, standard proctor and unconfined compressive strength were conducted. Results of the investigation showed significant improvement in drying rate and unconfined compressive strength of the CKD treated specimens as the percentage of CKD increased. It was also found that lower percentages of CKD can be used for modification purposes, whereas higher percentages of CKD can be used for both modification and stabilization purposes in geotechnical construction.     

高速公路路基膨胀土改性处理的实验研究

膨胀土工程地质性质很差,在被用作高等级公路的路基填料时,要进行改性处理.通过对一种典型膨胀土物理力学性质的研究及掺加石灰进行改性处理试验,得出了不同掺灰量、不同含水量及不同压实度对膨胀土性能的影响规律.在采用掺灰土填筑路基时,最好在大于最佳含水量的条件下压实,并且在可压实的情况下尽可能提高压实含水量及压实度,这样可大大减少路基的膨胀量及膨胀力.     

膨胀土地基强夯处理效果的研究

本文研究了河南某工地膨胀土地基的强夯处理效果,着重研究了强夯处理前后其工程地质、性质、胀缩特性等的差异,同时还讨论了这些差异与粘土矿物组成之间的关系。研究结果表明,经强夯处理后的膨胀土,其膨胀等级提高,膨胀压力明显增加,而不同荷载下的膨胀率或收缩率在一定深度内明显降低。     

膨胀土干缩变形特性试验研究

膨胀土是一种典型的问题性土,对气候变化非常敏感,在干旱气候条件下,极易发生体积收缩变形,引发各种工 程地质问题。为了研究膨胀土的干缩变形特性,开展了一系列室内干燥试验,测定了膨胀土的收缩特征曲线,重点分析 了初始含水率和干密度对干缩变形过程的影响,并进一步探讨了水泥固化抑制膨胀土干缩变形的效果和机理。结果表 明：（1） 膨胀土的干缩变形过程存在三个典型阶段：正常收缩、残余收缩和零收缩;（2） 初始含水率越高,试样蒸发速 率越快,且干缩变形完全后试样孔隙比越小而最终收缩应变越大,干缩变形越明显;（3） 初始干密度越大,试样蒸发速 率和最终体积收缩应变越小,提高初始干密度对试样干缩变形具有一定的抑制作用;（4） 在膨胀土中掺入适量的水泥能 显著降低试样的体积收缩应变,对干缩变形具有良好的抑制效果;（5） 膨胀土的干缩变形具有明显的各向异性特征,并 且与初始状态有关。     

膨胀土干缩变形特性试验研究

膨胀土是一种典型的问题性土，对气候变化非常敏感，在干旱气候条件下，极易发生体积收缩变形，引发各种工 程地质问题。为了研究膨胀土的干缩变形特性，开展了一系列室内干燥试验，测定了膨胀土的收缩特征曲线，重点分析 了初始含水率和干密度对干缩变形过程的影响，并进一步探讨了水泥固化抑制膨胀土干缩变形的效果和机理。结果表 明：（1） 膨胀土的干缩变形过程存在三个典型阶段：正常收缩、残余收缩和零收缩；（2） 初始含水率越高，试样蒸发速 率越快，且干缩变形完全后试样孔隙比越小而最终收缩应变越大，干缩变形越明显；（3） 初始干密度越大，试样蒸发速 率和最终体积收缩应变越小，提高初始干密度对试样干缩变形具有一定的抑制作用；（4） 在膨胀土中掺入适量的水泥能 显著降低试样的体积收缩应变，对干缩变形具有良好的抑制效果；（5） 膨胀土的干缩变形具有明显的各向异性特征，并 且与初始状态有关。     

Desiccation-Induced Volumetric Shrinkage of Compacted Foundry Sand Treated with Cement Kiln Dust

Foundry sand, an industrial waste, was treated with up to 12 % cement kiln dust content at comparative energy levels of British standard light, West African standard or “intermediate” (WAS) and British standard heavy (BSH) efforts at molding water contents ?2, 0, 2, 4 and 6 % of optimum moisture content. Samples were extruded from the compaction molds and allowed to air dry in the laboratory in order to assess the effect of desiccation-induced shrinkage on the material for use as a hydraulic barrier in waste containment application. Results recorded show that volumetric shrinkage strain (VSS) values were large within the first 5 days of drying; VSS values increased with higher molding water content, water content relative to the optimum moisture content. VSS generally increased with higher initial degree of saturation for all compactive efforts, irrespective of the level of cement kiln dust (CKD) treatment. A compaction plane of acceptable zones for VSS based on the regulatory value is ≤4 %. The influence of CKD treatment generally showed a decrease in the desiccation-induced volumetric shrinkage strain with increasing CKD content. This is largely due to the pozzolanic input of CKD. Finally, only the BSH compactive effort gave successful results of volumetric shrinkage strain at CKD treatment content of between 4 and 8 %, while 12 % CKD content produced successful volumetric shrinkage strain results at WAS and BSH compactive effort, respectively.     

土体腐殖质对水泥土固化的影响

结合软土工程实例,探讨了腐殖质对水泥土作用的规律性.试验结果表明:水泥土中结合态腐殖酸均与原土差异较大;水泥土中腐殖酸光密度E465 /E665 值变大,松结态w(C)FA /w(C)HA 变大,稳结态w(C)FA /w(C)HA 减小.在水泥土水化反应中,土体腐殖质与Ca 2 、Al 3 等生成钙键、铝键等复合体.