Shear capacity of reinforced recycled aggregate concrete: Roles of fracture-surface roughness and matrix strength

IF 6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics Pub Date : 2026-04-01 Epub Date: 2026-02-07 DOI:10.1016/j.tafmec.2026.105498

Sourav Chakraborty , Kolluru V.L. Subramaniam

{"title":"Shear capacity of reinforced recycled aggregate concrete: Roles of fracture-surface roughness and matrix strength","authors":"Sourav Chakraborty , Kolluru V.L. Subramaniam","doi":"10.1016/j.tafmec.2026.105498","DOIUrl":null,"url":null,"abstract":"<div><div>Recycled coarse aggregate (RCA) has gained popularity as a sustainable alternative to natural aggregate (NA) in concrete. However, for RCA to be widely adopted in structural applications, it is crucial to develop a thorough understanding of its behavior under various loading conditions. In particular, attention must be paid to the mechanisms governing failure and to the capacity of recycled aggregate concrete (RAC) under brittle failure modes. Two critical scenarios in this context are mode-I fracture, which is associated with tensile cracking, and flexure-shear loading conditions, which often dictate the ultimate strength and serviceability of reinforced concrete members. This paper investigates cracking under mode-I fracture and failure under flexure-shear loading in RAC for two different concrete matrix strengths. While RAC exhibited lower mechanical strengths than natural aggregate concrete (NAC), the 3D mapping of crack profiles revealed that shear performance is dictated by crack morphology. Increasing the matrix strength produces rougher crack surfaces in RAC, enhancing stress transfer. The progression of flexure-shear cracks is analyzed using digital image correlation (DIC). The failure is identified with a loss of shear stress transfer across the primary shear crack. Tensile strength (<em>f</em><sub>t</sub>), represented by the square root of compressive strength, does not capture the observed variation in the shear capacity in RAC. This study demonstrates that the reduced crack roughness in RCA results in an overall reduction in flexure-shear capacity in lower-strength mixes, while increased roughness offsets reduced tensile strength in higher-strength RAC. Consequently, compressive-strength-based conventional design criteria provide an inconsistent margin of safety because crack roughness is not accounted for. Design equations for consistent safety need to consider surface roughness as an input variable.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"143 ","pages":"Article 105498"},"PeriodicalIF":6.0000,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Theoretical and Applied Fracture Mechanics","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0167844226000649","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2026/2/7 0:00:00","PubModel":"Epub","JCR":"Q1","JCRName":"ENGINEERING, MECHANICAL","Score":null,"Total":0}

引用次数: 0

Abstract

Recycled coarse aggregate (RCA) has gained popularity as a sustainable alternative to natural aggregate (NA) in concrete. However, for RCA to be widely adopted in structural applications, it is crucial to develop a thorough understanding of its behavior under various loading conditions. In particular, attention must be paid to the mechanisms governing failure and to the capacity of recycled aggregate concrete (RAC) under brittle failure modes. Two critical scenarios in this context are mode-I fracture, which is associated with tensile cracking, and flexure-shear loading conditions, which often dictate the ultimate strength and serviceability of reinforced concrete members. This paper investigates cracking under mode-I fracture and failure under flexure-shear loading in RAC for two different concrete matrix strengths. While RAC exhibited lower mechanical strengths than natural aggregate concrete (NAC), the 3D mapping of crack profiles revealed that shear performance is dictated by crack morphology. Increasing the matrix strength produces rougher crack surfaces in RAC, enhancing stress transfer. The progression of flexure-shear cracks is analyzed using digital image correlation (DIC). The failure is identified with a loss of shear stress transfer across the primary shear crack. Tensile strength (f_t), represented by the square root of compressive strength, does not capture the observed variation in the shear capacity in RAC. This study demonstrates that the reduced crack roughness in RCA results in an overall reduction in flexure-shear capacity in lower-strength mixes, while increased roughness offsets reduced tensile strength in higher-strength RAC. Consequently, compressive-strength-based conventional design criteria provide an inconsistent margin of safety because crack roughness is not accounted for. Design equations for consistent safety need to consider surface roughness as an input variable.

查看原文本刊更多论文

钢筋再生骨料混凝土抗剪承载力：裂缝表面粗糙度和基体强度的作用

再生粗骨料（RCA）作为混凝土中天然骨料（NA）的可持续替代品而受到欢迎。然而，为了在结构应用中广泛采用RCA，深入了解其在各种载荷条件下的行为是至关重要的。特别是，必须注意控制破坏的机制和再生骨料混凝土（RAC）在脆性破坏模式下的能力。在这种情况下，两种关键情况是i型断裂，这与拉伸开裂有关，以及弯曲-剪切加载条件，这通常决定了钢筋混凝土构件的极限强度和使用能力。本文研究了两种不同混凝土基体强度下RAC型断裂开裂和弯剪荷载下的破坏。虽然RAC表现出比天然骨料混凝土（NAC）更低的机械强度，但裂缝剖面的三维映射显示，剪切性能由裂缝形态决定。在RAC中，增加基体强度会使裂纹表面变得粗糙，从而增强应力传递。利用数字图像相关（DIC）分析了弯剪裂纹的演化过程。破坏是通过主剪切裂缝上剪切应力传递的损失来确定的。抗拉强度（ft），由抗压强度的平方根表示，不能捕获在RAC中观察到的剪切能力变化。该研究表明，在低强度混合料中，RCA中裂纹粗糙度的降低导致弯曲-剪切能力的整体降低，而在高强度RAC中，粗糙度的增加抵消了抗拉强度的降低。因此，基于抗压强度的传统设计标准提供了不一致的安全裕度，因为没有考虑裂纹粗糙度。一致性安全的设计方程需要考虑表面粗糙度作为输入变量。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

Theoretical and Applied Fracture Mechanics 工程技术-工程：机械

CiteScore

8.40

自引率

18.90%

发文量

435

审稿时长

37 days

期刊介绍： Theoretical and Applied Fracture Mechanics'' aims & scopes have been re-designed to cover both the theoretical, applied, and numerical aspects associated with those cracking related phenomena taking place, at a micro-, meso-, and macroscopic level, in materials/components/structures of any kind. The journal aims to cover the cracking/mechanical behaviour of materials/components/structures in those situations involving both time-independent and time-dependent system of external forces/moments (such as, for instance, quasi-static, impulsive, impact, blasting, creep, contact, and fatigue loading). Since, under the above circumstances, the mechanical behaviour of cracked materials/components/structures is also affected by the environmental conditions, the journal would consider also those theoretical/experimental research works investigating the effect of external variables such as, for instance, the effect of corrosive environments as well as of high/low-temperature.