Transforming Waste Red-Bed Mudstone into Sustainable Controlled Low-Strength Materials: Mix Design for Enhanced Engineering Performance
Red-bed mudstone from civil excavation is often treated as waste due to its poor water stability and tendency to disintegrate. This study proposes a sustainable approach for its utilization in controlled low-strength material (CLSM) by blending it with cement and water. Laboratory tests evaluated th...
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2025-04-01
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| author | Wei Qi Na Fu Jianbiao Du Xianliang Wang Tengfei Wang |
| author_facet | Wei Qi Na Fu Jianbiao Du Xianliang Wang Tengfei Wang |
| author_sort | Wei Qi |
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| description | Red-bed mudstone from civil excavation is often treated as waste due to its poor water stability and tendency to disintegrate. This study proposes a sustainable approach for its utilization in controlled low-strength material (CLSM) by blending it with cement and water. Laboratory tests evaluated the fresh properties (i.e., flowability, bleeding rate, setting time, and subsidence rate) and hardened properties (i.e., compressive strength, drying shrinkage, and wet–dry durability) of the CLSM. The analysis focused on two main parameters: cement-to-soil ratio (<i>C</i>/<i>S</i>) and water-to-solid ratio (<i>W</i>/<i>S</i>). The results show that increasing <i>W</i>/<i>S</i> significantly improves flowability, while increasing <i>C</i>/<i>S</i> also contributes positively. Flowability decreased exponentially over time, with an approximately 30% loss recorded after 3 h. Bleeding and subsidence rates rose sharply with higher <i>W</i>/<i>S</i> but were only marginally affected by <i>C</i>/<i>S</i>. To meet performance requirements, <i>W</i>/<i>S</i> should be kept below 52%. In addition, the setting times remained within 24 h for all mixtures tested. Compressive strength showed a negative correlation with <i>W</i>/<i>S</i> and a positive correlation with <i>C</i>/<i>S</i>. When <i>C</i>/<i>S</i> ranged from 8% to 16% and <i>W</i>/<i>S</i> from 44% to 56%, the compressive strengths ranged from 0.3 MPa to 1.22 MPa, meeting typical backfilling needs. Drying shrinkage was correlated positively with water loss, and it decreased with greater <i>C</i>/<i>S</i>. Notably, cement’s addition significantly enhanced water stability. At a <i>C</i>/<i>S</i> of 12%, the specimens remained intact after 13 wet–dry cycles, retaining over 80% of their initial strength. Based on these findings, predictive models for strength and flowability were developed, and a mix design procedure was proposed. This resulted in two optimized proportions suitable for confined backfilling. This study provides a scientific basis for the resource-oriented reuse of red-bed mudstone in civil engineering projects. |
| format | Article |
| id | doaj-art-28fef410b4eb4a549392b8599de87c8b |
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| spelling | doaj-art-28fef410b4eb4a549392b8599de87c8b2025-08-20T01:50:45ZengMDPI AGBuildings2075-53092025-04-01159143910.3390/buildings15091439Transforming Waste Red-Bed Mudstone into Sustainable Controlled Low-Strength Materials: Mix Design for Enhanced Engineering PerformanceWei Qi0Na Fu1Jianbiao Du2Xianliang Wang3Tengfei Wang4Sichuan Engineering Research Center for Intelligent Operation and Maintenance of Rail Transit Lines, Chengdu Vocational & Technical College of Industry, Chengdu 610213, ChinaSchool of Intelligent Construction and Environmental Engineering, Chengdu Textile College, Chengdu 611731, ChinaMOE Key Laboratory of High-Speed Railway Engineering, School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, ChinaSichuan Engineering Research Center for Intelligent Operation and Maintenance of Rail Transit Lines, Chengdu Vocational & Technical College of Industry, Chengdu 610213, ChinaMOE Key Laboratory of High-Speed Railway Engineering, School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, ChinaRed-bed mudstone from civil excavation is often treated as waste due to its poor water stability and tendency to disintegrate. This study proposes a sustainable approach for its utilization in controlled low-strength material (CLSM) by blending it with cement and water. Laboratory tests evaluated the fresh properties (i.e., flowability, bleeding rate, setting time, and subsidence rate) and hardened properties (i.e., compressive strength, drying shrinkage, and wet–dry durability) of the CLSM. The analysis focused on two main parameters: cement-to-soil ratio (<i>C</i>/<i>S</i>) and water-to-solid ratio (<i>W</i>/<i>S</i>). The results show that increasing <i>W</i>/<i>S</i> significantly improves flowability, while increasing <i>C</i>/<i>S</i> also contributes positively. Flowability decreased exponentially over time, with an approximately 30% loss recorded after 3 h. Bleeding and subsidence rates rose sharply with higher <i>W</i>/<i>S</i> but were only marginally affected by <i>C</i>/<i>S</i>. To meet performance requirements, <i>W</i>/<i>S</i> should be kept below 52%. In addition, the setting times remained within 24 h for all mixtures tested. Compressive strength showed a negative correlation with <i>W</i>/<i>S</i> and a positive correlation with <i>C</i>/<i>S</i>. When <i>C</i>/<i>S</i> ranged from 8% to 16% and <i>W</i>/<i>S</i> from 44% to 56%, the compressive strengths ranged from 0.3 MPa to 1.22 MPa, meeting typical backfilling needs. Drying shrinkage was correlated positively with water loss, and it decreased with greater <i>C</i>/<i>S</i>. Notably, cement’s addition significantly enhanced water stability. At a <i>C</i>/<i>S</i> of 12%, the specimens remained intact after 13 wet–dry cycles, retaining over 80% of their initial strength. Based on these findings, predictive models for strength and flowability were developed, and a mix design procedure was proposed. This resulted in two optimized proportions suitable for confined backfilling. This study provides a scientific basis for the resource-oriented reuse of red-bed mudstone in civil engineering projects.https://www.mdpi.com/2075-5309/15/9/1439red-bed mudstonewaste utilizationcontrolled low-strength materialengineering performancefeasibilitymix design |
| spellingShingle | Wei Qi Na Fu Jianbiao Du Xianliang Wang Tengfei Wang Transforming Waste Red-Bed Mudstone into Sustainable Controlled Low-Strength Materials: Mix Design for Enhanced Engineering Performance Buildings red-bed mudstone waste utilization controlled low-strength material engineering performance feasibility mix design |
| title | Transforming Waste Red-Bed Mudstone into Sustainable Controlled Low-Strength Materials: Mix Design for Enhanced Engineering Performance |
| title_full | Transforming Waste Red-Bed Mudstone into Sustainable Controlled Low-Strength Materials: Mix Design for Enhanced Engineering Performance |
| title_fullStr | Transforming Waste Red-Bed Mudstone into Sustainable Controlled Low-Strength Materials: Mix Design for Enhanced Engineering Performance |
| title_full_unstemmed | Transforming Waste Red-Bed Mudstone into Sustainable Controlled Low-Strength Materials: Mix Design for Enhanced Engineering Performance |
| title_short | Transforming Waste Red-Bed Mudstone into Sustainable Controlled Low-Strength Materials: Mix Design for Enhanced Engineering Performance |
| title_sort | transforming waste red bed mudstone into sustainable controlled low strength materials mix design for enhanced engineering performance |
| topic | red-bed mudstone waste utilization controlled low-strength material engineering performance feasibility mix design |
| url | https://www.mdpi.com/2075-5309/15/9/1439 |
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