Flexural and fracture performance of fiber reinforced self compacting alkali activated concrete– A DOE approach

IF 5 2区 工程技术 Q1 ENGINEERING, MECHANICAL
{"title":"Flexural and fracture performance of fiber reinforced self compacting alkali activated concrete– A DOE approach","authors":"","doi":"10.1016/j.tafmec.2024.104630","DOIUrl":null,"url":null,"abstract":"<div><p>Owing to their much-reduced carbon footprint and lower embodied energy, compared to conventional Portland Cement (OPC-based) Concrete mixes, Alkali Activated Concrete (AAC) mixes represent a pivotal advancement towards achieving sustainability goals. The fracture properties were investigated using Three-Point Bending Tests (3-PBT) under the mode I failure mechanism. This study utilises Taguchi analysis to analyse and optimise Self-Compacting Alkali-Activated Concrete (SAAC), focusing mainly on its flexural strength and fracture characteristics. An L-16 orthogonal array of experiments with three input parameters − replacement of Blast Furnace Slag (BFS) with Fly ash (FA) (0 %, 30 %, 40 %, and 50 %), Steel Fibers (SF) volume content (0 %, 0.25 %, 0.5 % and 0.75 %) and Notch to Depth (a<sub>0</sub>/d) ratio (0.2,0.3,0.4 and 0.5), at four levels each, was adopted. The Work of Fracture Method (WFM) and Double K Fracture Criterion (DKFC) were utilised to determine the Fracture Energy (G<sub>F</sub>) and fracture toughness, respectively. The results obtained from all the sixteen mixes showed that the F0-S0.75-N0.5 mix demonstrated better values in several parameters, such as flexural strength of 7.82 MPa,<span><math><mrow><mspace></mspace><msubsup><mtext>K</mtext><mrow><mtext>IC</mtext></mrow><mtext>ini</mtext></msubsup></mrow></math></span> of 0.928 MPa√m, <span><math><mrow><msubsup><mrow><mspace></mspace><mtext>K</mtext></mrow><mrow><mtext>IC</mtext></mrow><mtext>uns</mtext></msubsup></mrow></math></span> of 6.99 MPa√m and <span><math><mrow><msubsup><mtext>K</mtext><mrow><mtext>IC</mtext></mrow><mtext>ini</mtext></msubsup></mrow></math></span>/ <span><math><mrow><msubsup><mtext>K</mtext><mrow><mtext>IC</mtext></mrow><mtext>uns</mtext></msubsup></mrow></math></span> of 0.133. A maximum G<sub>F</sub> of 2350 N/m was obtained with F50-S0.75-N0.2 mix. However, all the inferior values of these parameters were observed with F50-S0-N0.5 mix, which recorded a flexural strength of 4.90 MPa, <span><math><mrow><msubsup><mtext>K</mtext><mrow><mtext>IC</mtext></mrow><mtext>ini</mtext></msubsup></mrow></math></span> of 0.612 MPa√m,<span><math><mrow><msubsup><mrow><mspace></mspace><mtext>K</mtext></mrow><mrow><mtext>IC</mtext></mrow><mtext>uns</mtext></msubsup></mrow></math></span> of 1.16 MPa√m, <span><math><mrow><msubsup><mtext>K</mtext><mrow><mtext>IC</mtext></mrow><mtext>ini</mtext></msubsup></mrow></math></span>/ <span><math><mrow><msubsup><mtext>K</mtext><mrow><mtext>IC</mtext></mrow><mtext>uns</mtext></msubsup></mrow></math></span> of 0.528 and G<sub>F</sub> of 125 N/m. Through Taguchi analysis, the optimal combination for flexural strength was identified as FA 0 %, SF 0.75 %, and a<sub>0</sub>/d 0.5 and for both Initial Fracture Toughness (<span><math><mrow><msubsup><mtext>K</mtext><mrow><mtext>IC</mtext></mrow><mtext>ini</mtext></msubsup></mrow></math></span>) and Unstable Fracture Toughness (<span><math><mrow><msubsup><mtext>K</mtext><mrow><mtext>IC</mtext></mrow><mrow><mtext>un</mtext><mtext>s</mtext></mrow></msubsup></mrow></math></span>) at FA 0 %, SF 0.75 % and a<sub>0</sub>/d 0.4. For both the ratio of initial to unstable fracture toughness (<span><math><mrow><msubsup><mtext>K</mtext><mrow><mtext>IC</mtext></mrow><mtext>ini</mtext></msubsup></mrow></math></span>/ <span><math><mrow><msubsup><mtext>K</mtext><mrow><mtext>IC</mtext></mrow><mrow><mtext>un</mtext><mtext>s</mtext></mrow></msubsup></mrow></math></span>) and fracture energy (G<sub>F</sub>), the optimum combination was FA 0 %, SF 0.75 % and a<sub>0</sub>/d 0.2. Furthermore, the results indicate that FA significantly influences <span><math><mrow><msubsup><mtext>K</mtext><mrow><mtext>IC</mtext></mrow><mtext>ini</mtext></msubsup></mrow></math></span>, while SF predominantly affects all other parameters. The predictive performance of the regression equations demonstrates good agreement with experimental outcomes.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0000,"publicationDate":"2024-08-18","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/S016784422400380X","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENGINEERING, MECHANICAL","Score":null,"Total":0}
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Abstract

Owing to their much-reduced carbon footprint and lower embodied energy, compared to conventional Portland Cement (OPC-based) Concrete mixes, Alkali Activated Concrete (AAC) mixes represent a pivotal advancement towards achieving sustainability goals. The fracture properties were investigated using Three-Point Bending Tests (3-PBT) under the mode I failure mechanism. This study utilises Taguchi analysis to analyse and optimise Self-Compacting Alkali-Activated Concrete (SAAC), focusing mainly on its flexural strength and fracture characteristics. An L-16 orthogonal array of experiments with three input parameters − replacement of Blast Furnace Slag (BFS) with Fly ash (FA) (0 %, 30 %, 40 %, and 50 %), Steel Fibers (SF) volume content (0 %, 0.25 %, 0.5 % and 0.75 %) and Notch to Depth (a0/d) ratio (0.2,0.3,0.4 and 0.5), at four levels each, was adopted. The Work of Fracture Method (WFM) and Double K Fracture Criterion (DKFC) were utilised to determine the Fracture Energy (GF) and fracture toughness, respectively. The results obtained from all the sixteen mixes showed that the F0-S0.75-N0.5 mix demonstrated better values in several parameters, such as flexural strength of 7.82 MPa,KICini of 0.928 MPa√m, KICuns of 6.99 MPa√m and KICini/ KICuns of 0.133. A maximum GF of 2350 N/m was obtained with F50-S0.75-N0.2 mix. However, all the inferior values of these parameters were observed with F50-S0-N0.5 mix, which recorded a flexural strength of 4.90 MPa, KICini of 0.612 MPa√m,KICuns of 1.16 MPa√m, KICini/ KICuns of 0.528 and GF of 125 N/m. Through Taguchi analysis, the optimal combination for flexural strength was identified as FA 0 %, SF 0.75 %, and a0/d 0.5 and for both Initial Fracture Toughness (KICini) and Unstable Fracture Toughness (KICuns) at FA 0 %, SF 0.75 % and a0/d 0.4. For both the ratio of initial to unstable fracture toughness (KICini/ KICuns) and fracture energy (GF), the optimum combination was FA 0 %, SF 0.75 % and a0/d 0.2. Furthermore, the results indicate that FA significantly influences KICini, while SF predominantly affects all other parameters. The predictive performance of the regression equations demonstrates good agreement with experimental outcomes.

纤维增强自密实碱活性混凝土的挠曲和断裂性能--一种 DOE 方法
与传统的波特兰水泥(OPC)混凝土拌合物相比,碱活性混凝土(AAC)拌合物的碳足迹更小、能耗更低,因此在实现可持续发展目标方面具有举足轻重的地位。本研究使用三点弯曲试验(3-PBT)对模式 I 破坏机制下的断裂特性进行了研究。本研究利用田口分析法对自密实碱活性混凝土(SAAC)进行分析和优化,主要侧重于其抗弯强度和断裂特性。试验采用 L-16 正交阵列,三个输入参数分别为高炉矿渣(BFS)与粉煤灰(FA)的替代率(0 %、30 %、40 % 和 50 %)、钢纤维(SF)体积含量(0 %、0.25 %、0.5 % 和 0.75 %)以及缺口深度比(a0/d)(0.2、0.3、0.4 和 0.5),每个参数分为四个等级。断裂功法(WFM)和双 K 断裂标准(DKFC)分别用于确定断裂能(GF)和断裂韧性。从所有十六种混合料中得出的结果表明,F0-S0.75-N0.5 混合料在多个参数中表现出更好的值,如抗弯强度为 7.82 MPa,KICini 为 0.928 MPa√m,KICuns 为 6.99 MPa√m,KICini/ KICuns 为 0.133。F50-S0.75-N0.2 混合料的最大 GF 值为 2350 N/m。然而,F50-S0-N0.5 混合料的上述参数值均较低,其抗弯强度为 4.90 MPa,KICini 为 0.612 MPa√m,KICuns 为 1.16 MPa√m,KICini/ KICuns 为 0.528,GF 为 125 N/m。通过田口分析,确定了抗弯强度的最佳组合为 FA 0 %、SF 0.75 % 和 a0/d 0.5,初始断裂韧性(KICini)和不稳定断裂韧性(KICuns)的最佳组合为 FA 0 %、SF 0.75 % 和 a0/d 0.4。对于初始断裂韧性与不稳定断裂韧性之比(KICini/ KICuns)和断裂能(GF),最佳组合为 FA 0 %、SF 0.75 % 和 a0/d 0.2。此外,结果表明,FA 对 KICini 有显著影响,而 SF 则主要影响所有其他参数。回归方程的预测性能与实验结果非常吻合。
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来源期刊
Theoretical and Applied Fracture Mechanics
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.
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