Engineering and environmental evaluation of silty clay modified by waste fly ash and oil shale ash as a road subgrade material

Wei, Haibin; Zhang, Yangpeng; Cui, Jiuhui; Han, Leilei; Li, Ziqi

doi:10.1016/j.conbuildmat.2018.11.060

Cited by 49 publications

(24 citation statements)

References 28 publications

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“…Based on the existing research, the dry mass ratio of 2:1:2 for OSA/FA/SC and moisture content of 12.95% are selected to manufacture MSC because, through a series of conventional physical and mechanical property tests conducted by the authors, it was found that, under this ratio, the MSC has great shear strength, the smallest plasticity and the highest CBR value [20,21,29]. Table 2 lists the physical properties of MSC obtained from Refs [20,21,29]. The dry mass ratio of 2:1:2 for OSA/FA/SC and moisture content of 12.95% used in this study can be referred to Refs [20,21,29].…”

Section: Preparation Of Mixed Samples and Testing Samplesmentioning

confidence: 99%

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Experimental Research on Deformation Characteristics of Using Silty Clay Modified by Oil Shale Ash and Fly Ash as the Subgrade Material after Freeze-Thaw Cycles

Wei

Han

et al. 2019

Sustainability

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To achieve the purposes of disposing industry solid wastes and enhancing the sustainability of subgrade life-cycle service performance in seasonally frozen regions compared to previous research of modified silty clay (MSC) composed of oil shale ash (OSA), fly ash (FA), and silty clay (SC), we identified for the first time the axial deformation characteristics of MSC with different levels of cycle load number, dynamic stress ratio, confining pressure, loading frequency, and F-T cycles; and corresponding to the above conditions, the normalized and logarithmic models on the plastic cumulative strain prediction of MSC are established. For the effect of cycle load number, results show that the cumulative plastic strain of MSC after 1, 10, and 100 cycle loads occupies for 28.72%~35.31%, 49.86%~55.59%, and 70.87%~78.39% of those after 8000 cycle loads, indicating that MSC possesses remarkable plastic stability after 100 cycles of cycle loads. For the effect of dynamic stress ratio, confining pressure, loading frequency, and F-T cycles, results show that dynamic stress ratio and F-T cycles are important factors affecting the axial deformation of MSC after repeated cycle loads; and under the low dynamic stress ratio, increasing confining pressure and loading frequency have insignificant effect on the axial strain of MSC after 8000 loads. In term of the normalized and logarithmic models on the plastic cumulative strain prediction of MSC, they have a high correlation coefficient with testing data, and according to the above models, the predicted result shows that the cumulative plastic strain of MSC ranges from 0.38 cm to 2.71 cm, and these predicted values are within the requirements in the related standards of highway subgrades and railway, indicating that the cumulative plastic strain of MSC is small and MSC is suitable to be used as the subgrade materials.

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Section: Preparation Of Mixed Samples and Testing Samplesmentioning

confidence: 99%

“…Table 2 lists the physical properties of MSC obtained from Refs [20,21,29]. The dry mass ratio of 2:1:2 for OSA/FA/SC and moisture content of 12.95% used in this study can be referred to Refs [20,21,29]. Before manufacturing MSC, there are three steps.…”

Section: Preparation Of Mixed Samples and Testing Samplesmentioning

confidence: 99%

Experimental Research on Deformation Characteristics of Using Silty Clay Modified by Oil Shale Ash and Fly Ash as the Subgrade Material after Freeze-Thaw Cycles

Wei

Han

et al. 2019

Sustainability

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“…Turner [18] proved that the silty sand, which was processed with OSA, obtained significant improvement in strength, resilient modulus, and F-T durability. In previous literature, research on soil stabilization with both OSA and FA is inadequate, and it focuses on the author's previous research [11,15,23]. Wei et al [11,23] modified silty clay (SC) by OSA and FA (In the following interpretation, the silty clay, modified by OSA and FA, will be referred to as MC for short), and conducted a battery of laboratory tests to research the mechanical characteristics and environmental impacts of MC; research results showed that the modified SC was suitable for road construction in seasonally frozen areas.…”

Section: Raw Materialsmentioning

confidence: 99%

“…In previous literature, research on soil stabilization with both OSA and FA is inadequate, and it focuses on the author's previous research [11,15,23]. Wei et al [11,23] modified silty clay (SC) by OSA and FA (In the following interpretation, the silty clay, modified by OSA and FA, will be referred to as MC for short), and conducted a battery of laboratory tests to research the mechanical characteristics and environmental impacts of MC; research results showed that the modified SC was suitable for road construction in seasonally frozen areas. Li et al [15] proved the feasibility of using MC and the XPS board as a road subgrade thermal insulation layer, by the numerical modeling and environmental evaluation on an experiment road located in the Jilin province; however, in their numerical modeling, they viewed the specific heat capacity and thermal conductivity of the MC, XPS board, and SC under F-T cycles as a constant value, so their results could not show the real changes of their thermal insulation performance under freeze-thaw cycles, and thus, their research results exaggerated or belittled the thermal insulation effect of the MC and XPS board.…”

Section: Raw Materialsmentioning

confidence: 99%

Experimental and Numerical Research on Utilizing Modified Silty Clay and Extruded Polystyrene (XPS) Board as the Subgrade Thermal Insulation Layer in a Seasonally Frozen Region, Northeast China

Wei

Zhou

et al. 2019

Sustainability

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For strengthening sustainability of subgrade life-cycle service performance and storing industry solid wastes in seasonally frozen regions, compared to previous research of modified silty clay (MC) which consisted of oil shale ash (OSA), fly ash (FA), and silty clay (SC), we identified for the first time, the variations in the thermal insulation capability of MC with different levels of dry density and moisture content. Taking into consideration the effects of 0–20 freeze-thaw (F-T) cycles by a laboratory test, and by the numerical simulation of coupling moisture-temperature, while considering the effects of F-T cycles, the thermal insulation capability of the MC board and the XPS board were studied quantitatively. The testing results show that the thermal conductivity of MC and SC gradually decreases as the number of F-T cycles increases, and that of the XPS board increases with the increased number of F-T cycles, and tend to be of a constant value of 0.061 W/m/K after 17 F-T cycles. The specific heat capacity of the solid particles of the MC, SC, and XPS board does not change regularly as their moisture content, and the number of F-T cycles change, and their variations are in the range of the test error (2%). Simulation results show that MC has the advantage of the thermal insulation property to reduce the frost-depth of 0.21 m, and the thermal insulation property of the composite layer consisting of the MC and XPS board is greater to reduce the frost-depth of 0.55 m, so that it can protect both the SC and sand gravel of the experimental road from the frost heave damage. The research methods and results are very significant in accurately evaluating the thermal insulation capacity and the sustainability of MC and the composite layer consisting of the MC and XPS board, strengthening the stability of the subgrade and increasing the availability of industrial waste.

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“…Then, the materials were mixed at the dry mass ratio of OSA/FA/SC of 2:1:2 in the optimum moisture of 15%. This dry mass ratio was determined by a serious of conventional physical and mechanical property tests [30,31]. The modified soil at this ratio possesses the highest CBR value, great shear strength, appropriate physical properties, and a balanced usage ratio of FA, OSA, and SC.…”

Section: Mixed Materialsmentioning

confidence: 99%

Experimental Research on Resilient Modulus of Silty Clay Modified by Oil Shale Ash and Fly Ash after Freeze-Thaw Cycles

et al. 2018

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To dispose of the large amount of OSA (oil shale ash) and FA (fly ash) in Northeast China, a novel subgrade material obtained by modifying SC (silty clay) with OSA and FA was produced. First, the effect of F-T (freeze-thaw) cycles and stress states on the resilient modulus of unmodified SC and the modified SC were investigated. Second, the damage ratio was introduced to describe the relationship of resilient modulus versus F-T cycles. Third, the effect of F-T cycles on the microstructure of soils was investigated. The results indicate that in addition to stress state, resilient modulus is significantly influenced by F-T cycles. For unmodified SC, the resilient modulus continually decreases with increasing F-T cycles. As for the modified soil, the resilient modulus decreases sharply after the first F-T cycle and then tends to be stable. The damage ratio and its fitting equation are effectively adopted to describe the variation characteristic of the resilient modulus after F-T cycles. As observed from SEM testing, the effect of F-T cycles on soils is to destroy the initial structure and increase the porosity of soils. It could be concluded that the microstructure change during F-T cycles is the main factor that results in the decrease of the resilient modulus.

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Engineering and environmental evaluation of silty clay modified by waste fly ash and oil shale ash as a road subgrade material

Cited by 49 publications

References 28 publications

Experimental Research on Deformation Characteristics of Using Silty Clay Modified by Oil Shale Ash and Fly Ash as the Subgrade Material after Freeze-Thaw Cycles

Experimental Research on Deformation Characteristics of Using Silty Clay Modified by Oil Shale Ash and Fly Ash as the Subgrade Material after Freeze-Thaw Cycles

Experimental and Numerical Research on Utilizing Modified Silty Clay and Extruded Polystyrene (XPS) Board as the Subgrade Thermal Insulation Layer in a Seasonally Frozen Region, Northeast China

Experimental Research on Resilient Modulus of Silty Clay Modified by Oil Shale Ash and Fly Ash after Freeze-Thaw Cycles

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