Enhancing mechanical strength and reducing drying shrinkage in high-volume fly ash mortar: Synergistic effects of steel fibers and nano-SiO2

This study investigated the effects of steel fibers and nano-silica dioxide (nano-SiO2) on the fluidity, capillary water absorption, mechanical properties, and drying shrinkage of mortar when 50 % of the cement was replaced by fly ash. The mechanisms by which steel fibers and nano-SiO2 influence hig...

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Main Authors: Junliang Zhao, Jingjing Huang, Zhongkun Wang, Dongyan Wu, Gengying Li
Format: Article
Language:English
Published: Elsevier 2025-05-01
Series:Journal of Materials Research and Technology
Subjects:
Online Access:http://www.sciencedirect.com/science/article/pii/S223878542501186X
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author Junliang Zhao
Jingjing Huang
Zhongkun Wang
Dongyan Wu
Gengying Li
author_facet Junliang Zhao
Jingjing Huang
Zhongkun Wang
Dongyan Wu
Gengying Li
author_sort Junliang Zhao
collection DOAJ
description This study investigated the effects of steel fibers and nano-silica dioxide (nano-SiO2) on the fluidity, capillary water absorption, mechanical properties, and drying shrinkage of mortar when 50 % of the cement was replaced by fly ash. The mechanisms by which steel fibers and nano-SiO2 influence high-volume fly ash mortar were discussed based on macroscopic tests and microscopic structural analysis. The results show that while nano-SiO2 and steel fibers had negligible effects on the fluidity of fly ash mortar, they significantly enhanced its mechanical properties. When the steel fiber content was 1.0 % and the nano-SiO2 content was 2.0 %, the modified mortar exhibited increases in flexural and compressive strength by 86.4 % and 53.7 %, respectively, compared to the unmodified mortar at 28 days of age. Additionally, the incorporation of nano-SiO2 and steel fibers significantly reduced the capillary water absorption and drying shrinkage of the mortar. The capillary absorption rate of the 1.0 % steel fibers and 2.5 % nano-SiO2 composite mortar decreases 67.8 % compared to the fly ash mortar. At 90 days of age, the drying shrinkage of the modified mortar containing 1.0 % steel fibers and 2.5 % nano-SiO2 was reduced by 44.4 % compared to the unmodified mortar. Microstructural characterization through scanning electron microscopy (SEM) and X-ray diffraction (XRD) demonstrated that nano-SiO2 incorporation enhanced the hydration of both fly ash and cement, leading to a significant reduction in unhydrated fly ash particles. Furthermore, mercury intrusion porosimetry (MIP) tests demonstrated that the addition of nano-SiO2 and steel fibers markedly decreased the average and median pore sizes in the mortar, resulting in a more optimized pore structure distribution.
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spelling doaj-art-979f4a787c6142a7bddbca1bcd8df4e82025-08-20T03:48:51ZengElsevierJournal of Materials Research and Technology2238-78542025-05-01367351736010.1016/j.jmrt.2025.05.032Enhancing mechanical strength and reducing drying shrinkage in high-volume fly ash mortar: Synergistic effects of steel fibers and nano-SiO2Junliang Zhao0Jingjing Huang1Zhongkun Wang2Dongyan Wu3Gengying Li4College of Civil Engineering and Architecture, Wenzhou University, Wenzhou, 325035, Zhejiang, China; Key Laboratory of Engineering and Technology for Soft Soil Foundation and Tideland Reclamation of Zhejiang Province, Wenzhou, 325035, ChinaSchool of Civil Engineering & Architecture, Wenzhou Polytechnic, Wenzhou, 325035, China; Department of Civil Engineering and Smart Cities, Shantou University, Shantou, 515063, Guangdong, China; Corresponding author. School of Civil Engineering & Architecture, Wenzhou Polytechnic, Wenzhou, 325035, China.College of Civil Engineering and Architecture, Wenzhou University, Wenzhou, 325035, Zhejiang, China; Key Laboratory of Engineering and Technology for Soft Soil Foundation and Tideland Reclamation of Zhejiang Province, Wenzhou, 325035, ChinaCollege of Civil Engineering and Architecture, Wenzhou University, Wenzhou, 325035, Zhejiang, China; Key Laboratory of Engineering and Technology for Soft Soil Foundation and Tideland Reclamation of Zhejiang Province, Wenzhou, 325035, ChinaCollege of Water Conservancy and Civil Engineering, South China Agricultural University, Guangzhou, 510642, ChinaThis study investigated the effects of steel fibers and nano-silica dioxide (nano-SiO2) on the fluidity, capillary water absorption, mechanical properties, and drying shrinkage of mortar when 50 % of the cement was replaced by fly ash. The mechanisms by which steel fibers and nano-SiO2 influence high-volume fly ash mortar were discussed based on macroscopic tests and microscopic structural analysis. The results show that while nano-SiO2 and steel fibers had negligible effects on the fluidity of fly ash mortar, they significantly enhanced its mechanical properties. When the steel fiber content was 1.0 % and the nano-SiO2 content was 2.0 %, the modified mortar exhibited increases in flexural and compressive strength by 86.4 % and 53.7 %, respectively, compared to the unmodified mortar at 28 days of age. Additionally, the incorporation of nano-SiO2 and steel fibers significantly reduced the capillary water absorption and drying shrinkage of the mortar. The capillary absorption rate of the 1.0 % steel fibers and 2.5 % nano-SiO2 composite mortar decreases 67.8 % compared to the fly ash mortar. At 90 days of age, the drying shrinkage of the modified mortar containing 1.0 % steel fibers and 2.5 % nano-SiO2 was reduced by 44.4 % compared to the unmodified mortar. Microstructural characterization through scanning electron microscopy (SEM) and X-ray diffraction (XRD) demonstrated that nano-SiO2 incorporation enhanced the hydration of both fly ash and cement, leading to a significant reduction in unhydrated fly ash particles. Furthermore, mercury intrusion porosimetry (MIP) tests demonstrated that the addition of nano-SiO2 and steel fibers markedly decreased the average and median pore sizes in the mortar, resulting in a more optimized pore structure distribution.http://www.sciencedirect.com/science/article/pii/S223878542501186XHigh-volume fly ash mortarNano-SiO2Steel fibersFluidityMechanical propertiesDrying shrinkage
spellingShingle Junliang Zhao
Jingjing Huang
Zhongkun Wang
Dongyan Wu
Gengying Li
Enhancing mechanical strength and reducing drying shrinkage in high-volume fly ash mortar: Synergistic effects of steel fibers and nano-SiO2
Journal of Materials Research and Technology
High-volume fly ash mortar
Nano-SiO2
Steel fibers
Fluidity
Mechanical properties
Drying shrinkage
title Enhancing mechanical strength and reducing drying shrinkage in high-volume fly ash mortar: Synergistic effects of steel fibers and nano-SiO2
title_full Enhancing mechanical strength and reducing drying shrinkage in high-volume fly ash mortar: Synergistic effects of steel fibers and nano-SiO2
title_fullStr Enhancing mechanical strength and reducing drying shrinkage in high-volume fly ash mortar: Synergistic effects of steel fibers and nano-SiO2
title_full_unstemmed Enhancing mechanical strength and reducing drying shrinkage in high-volume fly ash mortar: Synergistic effects of steel fibers and nano-SiO2
title_short Enhancing mechanical strength and reducing drying shrinkage in high-volume fly ash mortar: Synergistic effects of steel fibers and nano-SiO2
title_sort enhancing mechanical strength and reducing drying shrinkage in high volume fly ash mortar synergistic effects of steel fibers and nano sio2
topic High-volume fly ash mortar
Nano-SiO2
Steel fibers
Fluidity
Mechanical properties
Drying shrinkage
url http://www.sciencedirect.com/science/article/pii/S223878542501186X
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AT zhongkunwang enhancingmechanicalstrengthandreducingdryingshrinkageinhighvolumeflyashmortarsynergisticeffectsofsteelfibersandnanosio2
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