Mechanical Properties and Working Mechanism of UHTCC with Recycled Fine Aggregate

doi:10.12068/j.issn.1005-3026.2025.20240016

Abstract

Abstract:

To investigate the effect of recycled fine aggregate （RFA） on the workability and mechanical properties of ultra-high toughness cementitious composites （UHTCC）， flowability， compressive strength， and uniaxial tensile tests were conducted on UHTCC with RFA replacement ratios of 0， 25%， 50%， 75%， and 100% for silica sand. The results indicate that the RFA replacement ratio has little effect on the flowability of UHTCC. Both the compressive and uniaxial tensile strengths of UHTCC decrease with increasing RFA replacement ratios， with a more pronounced reduction observed after the RFA replacement ratio exceeds 50%， decreasing by 13.9%~19.9% and 11.3%~16.7%， respectively， compared to specimens with pure silica sand aggregate. Under direct tension， the ultimate strain and crack numbers in UHTCC increase with higher RFA replacement ratios. When the RFA replacement ratio reaches 50%， the ultimate strain increases by 27.2%~40.9% compared to specimens with pure silica sand aggregate， and the specimens gradually exhibit a “saturated” fine and dense multi-crack failure mode. Microstructural analysis indicates that increasing the RFA replacement ratio facilitates the pull-out of PVA fibers from the UHTCC matrix， enhancing the fiber bridging effect across cracks.

Key words: ultra-high toughness cementitious composite, recycled fine aggregate, workability, mechanical property, replacement ratio

CLC Number:

TU 528.572

Meng CHEN, Fu-cheng LIU, Tong ZHANG, Di WU. Mechanical Properties and Working Mechanism of UHTCC with Recycled Fine Aggregate[J]. Journal of Northeastern University(Natural Science), 2025, 46(9): 119-125.

Figures/Tables 14

Fig.1 Particle size distribution of raw materials

Fig.2 Microstructural images of silica sand and RFA

Table 1 Physical properties of PVA fibers

长度	直径	抗拉强度	弹性模量	密度
mm	μm	MPa	GPa	kg·m^-3
12	39	1 600	40	1 300

Table 2 Mix proportions of UHTCC

编号	水泥	粉煤灰	石英砂	RFA	水	减水剂	PVA纤维
S100R0	544	653	435	0	335	14	26
S75R25	544	653	326	109	335	14	26
S50R50	544	653	218	218	335	14	26
S25R75	544	653	109	326	335	14	26
S0R100	544	653	0	435	335	14	26

Fig.3 Schematic diagram of uniaxial tensile test device and specimen dimensions

Fig.4 Variation of RFA replacement ratio on flowability of UHTCC

Fig.5 Variation of RFA replacement ratio on compressive strength of UHTCC

Fig.6 Variation of RFA replacement ratios on stress-strain curves of UHTCC

Fig.7 Microscopic morphology of PVA fibers at UHTCC crack

Fig.8 Variation of RFA replacement ratio on crack distribution of UHTCC

Fig.9 Variation of RFA replacement ratio on tensile strength of UHTCC

Fig.10 Variation of RFA replacement ratio on ultimate strain of UHTCC

Fig.11 Schematic illustration of action mechanism of RFA in UHTCC

Fig.12 SEM images of PVA fibers in fractured specimen

References 19

[1]	徐世烺，李贺东. 超高韧性水泥基复合材料直接拉伸试验研究［J］. 土木工程学报， 2009， 42（9）： 32-41.
	Xu Shi-lang， Li He-dong. Uniaxial tensile experiments of ultra-high toughness cementitious composite［J］. China Civil Engineering Journal， 2009， 42（9）： 32-41.
[2]	Li V C. Engineered cementitious composites （UHTCC）： bendable concrete for sustainable and resilient infrastructure［M］.Germany： Springer， 2019： 1-15.
[3]	肖建庄，叶涛华，隋同波，等. 废弃混凝土再生微粉的基本问题及应用［J］．材料导报， 2023， 37（10）：5-14.
	Xiao Jian-zhuang， Ye Tao-hua， Sui Tong-bo， et al. Fundamental problems and applications of recycled fine powder derived from waste concrete［J］. Materials Reports， 2023， 37（10）： 5-14.
[4]	Duan Z H， Hou S D， Xiao J Z， et al. Study on the essential properties of recycled powders from construction and demolition waste［J］. Journal of Cleaner Production， 2020， 253： 119865.
[5]	Cuenca-Moyano G M， Martín-Pascual J， Martín-Morales M， et al. Effects of water to cement ratio， recycled fine aggregate and air entraining/plasticizer admixture on masonry mortar properties［J］. Construction and Building Materials， 2020， 230： 116929.
[6]	Ju M， Park K， Park W J. Mechanical behavior of recycled fine aggregate concrete with high slump property in normal- and high-strength［J］. International Journal of Concrete Structures and Materials， 2019， 14（1）： 109-121.
[7]	Bai M Y， Wu Y C， Xiao J Z， et al. Workability and hardened properties of 3D printed engineered cementitious composites incorporating recycled sand and PE fibers［J］. Journal of Building Engineering， 2023， 71： 106477.
[8]	曹明莉，许玲，张聪. 高延性纤维增强水泥基复合材料的微观力学设计、性能及发展趋势［J］. 硅酸盐学报， 2015， 43（5）： 632-642.
	Cao Ming-li， Xu Ling， Zhang Cong. Review on micromechanical design， performance and development tendency of engineered cementitious composite［J］. Journal of the Chinese Ceramic Society， 2015， 43（5）： 632-642.
[9]	Yokota H， Rokugo K， Sakata N. Recommendations for design and construction of high performance fiber reinforced cement composite with multiple fine cracks （HPFRCC）［J］. Japan Society of Civil Engineers， 2008， 82： 6-10.
[10]	Lotfy A， Al-Fayez M. Performance evaluation of structural concrete using controlled quality coarse and fine recycled concrete aggregate［J］. Cement and Concrete Composites， 2015， 61： 36-43.
[11]	Leite M B， Figueire do Filho J G L， Lima P R L. Workability study of concretes made with recycled mortar aggregate［J］. Materials and Structures， 2013， 46（10）： 1765-1778.
[12]	杜婷．高性能再生混凝土微观结构及性能试验研究［D］．武汉：华中科技大学，2006．
	Du Ting. Experimental study on the microstructure and basic behaviors of recycled high performance concrete［D］. Wuhan： Huazhong University of Science and Technology， 2006.
[13]	Wang X J， Wu Y J， Zhu P H， et al. Improvement of mechanical properties and carbonation durability of recycled fine aggregate engineered cementitious composites for structural strengthening［J］. Journal of Building Engineering， 2023， 76： 107277.
[14]	Liu J， Ma K L， Shen J B， et al. Influence of recycled concrete aggregate enhancement methods on the change of microstructure of ITZs in recycled aggregate concrete［J］. Construction and Building Materials， 2023， 371： 130772.
[15]	闫增辉. 低温养护再生混凝土粉超高韧性水泥基复合材料力学性能研究［D］. 郑州：郑州大学， 2021.
	Yan Zeng-hui. Study on mechanical properties of ultra-high toughness cement-based composites with recycled concrete powder cured at low temperature［D］. Zhengzhou： Zhengzhou University， 2021.
[16]	Tosun-Felekoğlu K， Felekoğlu B， Ranade R， et al. The role of flaw size and fiber distribution on tensile ductility of PVA-ECC［J］. Composites Part B： Engineering， 2014， 56： 536-545.
[17]	Adesina A， Das S. Development of sustainable engineered cementitious composites using recycled concrete aggregates—feasibility study based on mechanical properties［J］. ACI Materials Journal， 2021， 118（4）： 97-107.
[18]	Curosu I， Liebscher M， Alsous G， et al. Tailoring the crack-bridging behavior of strain-hardening cement-based composites （SHCC） by chemical surface modification of poly（vinyl alcohol）（PVA） fibers［J］. Cement and Concrete Composites， 2020， 114： 103722.
[19]	Bai M Y， Xiao J Z， Gao Y， et al. Pore structure characteristics and mechanical property of engineered cementitious composites （ECC） incorporating recycled sand［J］. Construction and Building Materials， 2023， 408： 133721.