摘要
评估了再生粗集料(RCA)取代率对再生混凝土(RAC)力学性能和冲击磨耗性能的影响规律,建立了RAC的冲击磨耗时变模型,并在此基础上开展了基于纤维和再生橡胶颗粒复掺的RAC冲击磨耗性能调控方法研究.结果表明:RAC的冲击磨耗性能随RCA取代率增大呈下降趋势,并与其各项力学性能指标之间具有较高的相关性;纤维和再生橡胶颗粒的掺入能够改善RAC的冲击磨耗性能.
中国每年的废混凝土排放量已近20亿
道路与桥梁工程用混凝土材料表面易受磨损和侵蚀,耐磨性能指标是关系到其使用寿命的重要因素,受水灰比、力学性能以及所采用集料基本属性的影响较
本文旨在考察RCA取代率对RAC力学性能和冲击磨耗性能的影响,并对比分析纤维种类和再生橡胶颗粒粒度对RAC冲击磨耗性能的作用机制.
水泥为P·O 42.5普通硅酸盐水泥;细集料(FA)为细度模数2.71的机制砂;粗集料(CA)包括天然碎石(NCA)和废混凝土破碎加工得到的RCA.废混凝土来自广州市一座旧桥改扩建的构件拆除工程,其原始抗压强度为40~60 MPa.集料的基本性能见
Aggregate | Apparent density/(kg· | Water absorption (by mass)/% | Crushing index (by mass)/% |
---|---|---|---|
NCA | 2 651 | 0.76 | 7.8 |
RCA | 2 631 | 4.18 | 12.3 |
FA | 2 565 | 1.43 |

图1 集料的级配曲线
Fig.1 Gradation curves of aggregates
Fiber | Length/mm | Diameter/μm | Tensile strength/MPa | Elastic modulus/GPa | Density/(kg· |
---|---|---|---|---|---|
PE | 6 | 27 | 2 500 | 117 | 970 |
PVA | 6 | 15 | 1 830 | 40 | 1 290 |
基准组(RC0)全部采用NCA,不采用任何外掺料,水灰比、集灰比分别为0.43、2.58.为考察RCA取代率S对RAC性能的影响,采用RCA等体积取代NCA,设定S=0%、25%、50%、75%、100%,并记为RC0、RC25、RC50、RC75、RC100;集料按其饱和面干表观密度计算,考虑RCA的高吸水率特性,根据其实际含水率添加相应的附加水,以确保其有效水灰比保持不变.在RC50中分别加入占水泥用量3%的PE、PVA纤维,并分别记为FRC1、FRC2;在RC50中分别加入33 kg/
Specimen | Cement | Water | Sand | NCA | RCA | Additional water |
---|---|---|---|---|---|---|
RC0 | 394.0 | 170.0 | 798.0 | 1 016.0 | 0 | 0 |
RC25 | 394.0 | 170.0 | 798.0 | 762.0 | 252.0 | 10.6 |
RC50 | 394.0 | 170.0 | 798.0 | 508.0 | 504.0 | 21.1 |
RC75 | 394.0 | 170.0 | 798.0 | 254.0 | 756.0 | 31.7 |
RC100 | 394.0 | 170.0 | 798.0 | 0 | 1 008.0 | 42.2 |
试件拆模后置于(20±2) ℃、相对湿度RH≥95%的标准养护室养护28 d后,根据JTG E30—2005《公路工程水泥及水泥混凝土试验规程》,进行混凝土抗压强度、抗折强度、弹性模量的测试,其相应的试件尺寸分别为100 mm × 100 mm ×100 mm、100 mm × 100 mm×400 mm、100 mm × 100 mm × 300 mm.抗压强度和抗折强度试验的加载速率分别为0.60、0.06 MPa/s.
根据ASTM C131《Standard test method for resistance to degradation of small‑size coarse aggregate by abrasion and impact in the Los Angeles machine》,采用洛杉矶磨耗机测试混凝土试件的冲击磨耗性能.该方法用于评估粗集料的耐磨性能,其磨损机制是由摩擦、冲击和研磨等作用的组
RCA取代率对RAC力学性能的影响见

图2 RCA取代率对RAC力学性能的影响
Fig.2 Effect of R of RCA on mechanical properties of RAC
纤维种类对RAC力学性能的影响见

图3 纤维种类对RAC力学性能的影响
Fig.3 Effect of fiber type on mechanical properties of RAC
再生橡胶颗粒粒径对RAC力学性能的影响见

图4 再生橡胶颗粒粒径对RAC力学性能的影响
Fig.4 Effect of recycled rubber particles size on mechanical properties of RAC
经历不同旋转次数后RAC的破坏形貌见

图5 经历不同旋转次数后RAC的破坏形貌
Fig.5 Failure morphologies of RAC at different revolutions
RCA取代率对RAC冲击磨耗时变曲线的影响见

图6 RCA取代率对RAC冲击磨耗时变曲线的影响
Fig.6 Effect of R of RCA on abrasion resistance time‑varying curves of RAC
随着磨耗的不断累积,RAC试件边缘逐渐变得平滑,磨耗速率逐渐减小.
(1) |
式中:A、B为待定系数.
RAC冲击磨耗时变拟合曲线参数见
(2) |
Specimen | A×1 | B×1 | ||
---|---|---|---|---|
RC0 | -8.39 | 1.91 | 0.987 2 | 0.997 2 |
RC25 | -7.35 | 1.76 | 0.987 3 | 0.996 6 |
RC50 | -7.11 | 1.61 | 0.995 3 | 0.996 7 |
RC75 | -6.23 | 1.60 | 0.992 1 | 0.993 0 |
RC100 | -6.08 | 1.49 | 0.994 0 | 0.993 6 |
系数A、B的函数表达式A(S)和B(S)可简单认为服从一次函数关系,即系数A、B随RCA取代率S的增加呈线性变化.采用Pearson函数进行模型验证,结果也列于
RAC的磨耗率与力学性能的相关性见

图7 RAC磨损率与力学性能的相关性
Fig.7 Correlation between abrasion rate and mechanical properties of RAC
纤维种类对RAC冲击磨耗时变曲线的影响见

图8 纤维种类对RAC磨耗时变曲线的影响
Fig.8 Effect of fiber type on time‑varying abrasion curve of RAC
再生橡胶颗粒粒径对RAC冲击磨耗性能的影响见

图9 再生橡胶颗粒粒径对RAC冲击磨耗性能的影响
Fig.9 Effect of recycled rubber particle size on abrasion resistance of RAC
(1)再生混凝土(RAC)的力学性能随再生粗集料(RCA)取代率增加均呈下降趋势;纤维掺入可有效提高RAC的抗折强度和弹性模量,但对抗压强度的增强效果不显著;掺加粒径较小再生橡胶颗粒的RAC力学性能劣化明显.
(2)随着RCA取代率的增加,RAC冲击磨耗性能呈下降趋势;聚乙烯(PE)、聚乙烯醇(PVA)纤维的掺入使RAC冲击磨耗性能分别提升了31.19%和16.92%;再生橡胶颗粒掺入后,RAC的冲击磨耗性能降幅相较于抗压强度和抗折强度略低.
(3)RAC的冲击磨耗性能与力学性能指标均具有较好的相关性,其中与抗折强度相关性最高;提出了基于RCA取代率的RAC冲击磨耗时变模型,可有效预测RAC冲击磨耗性能随RCA取代率和磨耗次数的演化规律.
参考文献
WANG J Y, WU H Y, TAM V W Y, et al. Considering life‑cycle environmental impacts and society's willingness for optimizing construction and demolition waste management fee: An empirical study of China[J]. Journal of Cleaner Production, 2019, 206:1004‑1014. [百度学术]
ABID S R, HILO A N, AYOOB N S, et al. Underwater abrasion of steel fiber‑reinforced self‑compacting concrete [J]. Case Studies in Construction Materials, 2019, 11:e00299. [百度学术]
王彩辉, 禹华伟, 彭建, 等. 混凝土在耐磨性方面的研究进展 [J]. 混凝土, 2016 (7):17‑23. [百度学术]
WANG Caihui, YU Huawei, PENG Jian, et al. Development of concrete in abrasion resistance ceramics [J]. Concrete, 2016 (7):17‑23. (in Chinese) [百度学术]
杨宁, 王崇革, 赵美霞. 再生混凝土耐磨性影响因素研究 [J]. 公路, 2011 (6):171‑174. [百度学术]
YANG Ning, WANG Chongge, ZHAO Meixia. Research on influence factors of abrasion resistance for recycled aggregate concrete [J]. Highway, 2011 (6):171‑174. (in Chinese) [百度学术]
李北星, 柯国炬, 赵尚传, 等. 机制砂混凝土路用性能的研究 [J]. 建筑材料学报, 2010, 13(4):529‑534. [百度学术]
LI Beixing, KE Guoju, ZHAO Shangchuan, et al. Research on pavement performance of manufactured sand concrete [J]. Journal of Building Materials, 2010, 13(4):529‑534. (in Chinese) [百度学术]
亢景付, 范昆. 橡胶混凝土抗冲磨性能 [J]. 天津大学学报, 2011, 44(8):727‑731. [百度学术]
KANG Jingfu, FAN Kun. Abrasion resistance of rubberized concrete [J]. Journal of Tianjin University, 2011, 44(8):727‑731. (in Chinese) [百度学术]
陈守开, 张政男, 郑永杰, 等. 再生骨料透水混凝土耐撞磨性试验研究 [J]. 长江科学院院报, 2020, 37(7):153‑159. [百度学术]
CHEN Shoukai, ZHANG Zhengnan, ZHENG Yongjie, et al. Experimental study on impact‑abrasion resistance of recycled aggregate pervious concrete [J]. Journal of Yangtze River Scientific Research Institute, 2020, 37(7):153‑159. (in Chinese) [百度学术]
XIAO J Z, LI L, SHEN L M, et al. Compressive behaviour of recycled aggregate concrete under impact loading [J]. Cement and Concrete Research, 2015, 71:46‑55. [百度学术]
XIAO J Z, LI W G, CORR D J, et al. Effects of interfacial transition zones on the stress‑strain behavior of modeled recycled aggregate concrete [J]. Cement and Concrete Research, 2013, 52:82‑99. [百度学术]
LIU Q, XIAO J Z, SUN Z H. Experimental study on the failure mechanism of recycled concrete [J]. Cement and Concrete Research, 2011, 41(10):1050‑1057. [百度学术]
SILVA R V, BRITO J, DHIR R K. Establishing a relationship between modulus of elasticity and compressive strength of recycled aggregate concrete [J]. Journal of Cleaner Production, 2016, 112:2171‑2186. [百度学术]
XIAO J Z, LI J B, ZHANG C. On relationships between the mechanical properties of recycled aggregate concrete:An overview [J]. Materials and Structures, 2006, 39(6):655‑664. [百度学术]
WANG Y C, LIU F C, YU J T, et al. Effect of polyethylene fiber content on physical and mechanical properties of engineered cementitious composites [J]. Construction and Building Materials, 2020, 251:118917. [百度学术]
DIMAGGIO R, FRANCHINI M, GUERRINI G, et al. Fibre‑matrix adhesion in fibre reinforced CAC‑MDF composites [J]. Cement and Concrete Composites, 1997, 19(2):139‑147. [百度学术]
王龙, 池寅, 徐礼华, 等. 混杂纤维超高性能混凝土力学性能尺寸效应 [J]. 建筑材料学报, 2022, 25(8):781‑788. [百度学术]
WANG Long, CHI Yin, XU Lihua, et al. Size effect of mechanical properties of hybrid fiber ultra‑high performance concrete [J]. Journal of Building Materials, 2022, 25(8):781‑788. (in Chinese) [百度学术]
张玉武, 晏麓晖, 梁乔恒, 等. 超高分子量聚乙烯纤维混凝土静态力学性能研究 [J]. 工程科学与技术, 2017, 49(增刊2):257‑262. [百度学术]
ZHANG Yuwu, YAN Lihui, LIANG Qiaoheng, et al. Research on the static mechanical properties of ultra‑high molecular weight polyethylene fiber reinforced concrete [J]. Advanced Engineering Sciences, 2017, 49(Suppl 2):257‑262.(in Chinese) [百度学术]
屠艳平, 程子扬, 程书凯, 等. 橡胶粒径和掺量对再生混凝土性能的影响 [J]. 功能材料, 2021, 52(12):12072‑12078. [百度学术]
TU Yanping, CHENG Ziyang, CHENG Shukai, et al. Effect of rubber particle size and content on properties of recycled concrete [J]. Journal of Functional Materials, 2021, 52(12):12072‑12078.(in Chinese) [百度学术]
丁庆军, 李进辉, 耿雪飞, 等. 橡胶颗粒掺杂提高超高性能混凝土的抗冲磨性能及其机理 [J]. 硅酸盐学报, 2020, 48(10):1636‑1643. [百度学术]
DING Qingjun, LI Jinhui, GENG Xuefei, et al. Mechanism of enhancing anti‑abrasion performance of ultrahigh‑performance concrete via rubber particles [J]. Journal of the Chinese Ceramic Society, 2020, 48(10):1636‑1643.(in Chinese) [百度学术]