吉林大学学报(工学版) ›› 2021, Vol. 51 ›› Issue (6): 2121-2127.doi: 10.13229/j.cnki.jdxbgxb20200590

• 交通运输工程·土木工程 • 上一篇    

掺锂渣再生混凝土三点弯曲梁双K断裂特性

秦拥军(),陈楠,蔺鹏杰,于江   

  1. 新疆大学 建筑工程学院,乌鲁木齐 830047
  • 收稿日期:2020-11-07 出版日期:2021-11-01 发布日期:2021-11-15
  • 作者简介:秦拥军(1970-),男,教授,博士生导师. 研究方向:高性能混凝土,结构、再生混凝土. E-mail:1608513843@qq.com
  • 基金资助:
    国家自然科学基金项目(51668061)

Double K fracture characteristics of recycled concrete three⁃point bending beam mixed with lithium slag

Yong-jun QIN(),Nan CHEN,Peng-jie LIN,Jiang YU   

  1. School of Civil Engineering and Architecture,Xinjiang University,Urumqi 830047,China
  • Received:2020-11-07 Online:2021-11-01 Published:2021-11-15

摘要:

为研究锂渣掺量和再生粗骨料取代率对掺锂渣再生混凝土双K断裂韧度的影响规律,试验制作了锂渣掺量分别为0%、10%、20%和再生粗骨料取代率分别为0%、30%、50%的9组配比36根掺锂渣再生混凝土标准三点弯曲梁进行断裂测试,并在分析裂缝扩展过程的基础上提出了混凝土断裂韧度预估模型。试验结果表明:随着再生粗骨料取代率的增大,混凝土双K断裂韧度均呈现先增大、后减小的趋势;锂渣的掺入可以提高混凝土的双K断裂韧度,且在一定程度上弥补高再生粗骨料取代率导致混凝土断裂韧度小的不足;锂渣掺量为20%、再生粗骨料取代率为30%时,混凝土双K断裂特性最优,起裂韧度和失稳韧度分别为0.54 MPa·m1/2和1.07 MPa·m1/2,较基准组分别提高了42.1%和23%。

关键词: 锂渣, 再生粗骨料, 三点弯曲梁, 双K断裂韧度

Abstract:

To study the effects of different lithium slag contents and recycled coarse aggregate percentages on the double-K fracture toughness of recycled concrete with lithium slag, 36 standard three-point bending beams of recycled concrete with lithium slag, which include 9 mix ratios about lithium slag content of 0%,10%,20% and recycled coarse aggregate percentage of 0%,30%,50%, were prepared for fracture test. Based on the analysis of crack propagation process, a prediction model for fracture toughness of concrete was proposed. The research results show that the double K fracture toughness of concrete all increases first and then decreases with the increase of the recycled coarse aggregate percentage. The addition of lithium slag can improve the double K fracture toughness of the concrete and offset the deficiency of the concrete fracture performance with high recycled coarse aggregate percentage. The double K properties are optimal when the lithium slag content and recycled coarse aggregate account for 20 % and 30 % respectively. The initial fracture toughness and unstable fracture toughness reach 0.54 MPa·m1/2 and1.07 MPa·m1/2, increasing by 42.1% and 23 % respectively compared with the reference group.

Key words: lithium slag, recycled coarse aggregate, three point bending beam, double-K fracture toughness

中图分类号: 

  • TU528

表1

水泥和锂渣的质量分数 (%)"

材料CaOSiO2Al2O3Li2OLossFe2O3SO3
水泥60.2321.265.03-2.173.242.65
锂渣7.9954.4019.810.186.721.418.31

表2

粗骨料主要物理性能"

粗骨料类别微粉含量/%吸水率/%针片状含量/%坚固性/%表观密度/(kg·m-3
天然0.30.5512640
再生0.53.4624.22825

表3

混凝土配合比及力学性能参数"

编号RC/%LS/%混凝土配合比/(kg·m-3

28 d抗压

强度/MPa

劈裂拉强度/MPa
锂渣再生粗骨料净用水卵石水泥附加用水
LS-RC-10000195523.51221.4433.0034.723.38
LS-RC-201043.30195523.51221.4389.7036.464.06
LS-RC-302086.60195523.51221.4346.4040.584.27
LS-RC-43000366.4195523.5854.9433.07.8442.093.82
LS-RC-5301043.3366.4195523.5854.9389.77.8444.624.23
LS-RC-6302086.6366.4195523.5854.9346.47.8447.534.38
LS-RC-75000610.7195523.5610.7433.013.0737.243.56
LS-RC-8501043.4610.7195523.5610.7389.713.0740.864.03
LS-RC-9502086.6610.7195523.5610.7346.413.0742.834.19

图1

混凝土三点弯曲梁试件"

图2

电阻应变片定位显示图"

图3

P-ε曲线"

表4

双K断裂模型计算的断裂参数"

编号试件数量Pini/kNPmax/kNCMOD/μmE/GPaac/mmKIcini/(MPa·m1/2KIcun/(MPa·m1/2
LS-RC-141.522.4644.5629.3500.380.87
LS-RC-241.762.6646.2131.0520.440.93
LS-RC-341.822.9048.3430.7510.440.95
LS-RC-441.752.5846.2831.1520.440.93
LS-RC-541.92.7749.6731.5530.481.03
LS-RC-642.152.9751.9331.9520.541.07
LS-RC-741.482.3746.2828.6510.370.83
LS-RC-841.572.5850.7529.0520.390.96
LS-RC-941.642.7352.1530.6510.411.01

图4

P-CMOD曲线"

图5

断裂韧度与劈裂抗拉强度拟合曲线"

图6

LS对双K断裂参数的影响"

图7

RCA对双K断裂参数的影响"

图8

相同锂渣掺量下再生粗骨料取代率对双K韧度的影响"

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