Experiment on mechanical properties of steel fiber recycled aggregate concrete under triaxial compression
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摘要: 为了研究钢纤维再生混凝土(SFRAC)的三轴受压力学性能,以侧向围压、再生骨料取代率和钢纤维体积掺量为参数,设计了168个圆柱体试件进行常规三轴受压试验。试验观察了SFRAC的破坏形态,获取了应力-应变全曲线、峰值应力、峰值应变、弹性模量等重要指标,深入分析了不同变化参数对其力学性能的影响规律。结果表明,三轴受压下试件主要发生斜向劈裂破坏;随着围压值增大,应力-应变曲线峰部抬高,下降段变缓,峰值应力、峰值应变和弹性模量均显著增大;钢纤维可提高试件单轴受压时的残余强度,使其应力-应变曲线的下降段变缓;再生骨料取代率增加,试件的峰值应力与弹性模量降低,峰值应变增大;三轴受压状态下,钢纤维对SFRAC的峰值应力影响不大,钢纤维体积分数为1vol%时对SFRAC变形性能的改性效果最优。最后,提出了SFRAC三向受压时峰值应力、峰值应变及弹性模量的计算公式。Abstract: In order to study the mechanical properties of steel fiber recycled aggregate concrete (SFRAC) under triaxial compression, 168 cylinder specimens were tested by considering the parameters of the lateral confining pressure, the replacement rate of recycled coarse aggregate and the volume fraction of steel fiber. The failure pattern of the specimens was observed in the test. The stress-strain curve, peak stress, peak strain and elastic modulus were obtained. Based on the test data, the influence of different parameters on the mechanical performance was analyzed. The results show that under triaxial compression, the specimens are destroyed by oblique splitting. With the increase of confining pressure, the peak of stress-strain curve increases, while the descending section becomes slower, the peak stress, peak strain and elastic modulus of SFRAC all increase significantly. Steel fiber increases the residual strength of the specimen under uniaxial compression and makes the descending section of the stress-strain curve slow down. With the increase of the replacement rate of recycled coarse aggregate, the peak stress and elastic modulus decrease and the peak strain increases. Under triaxial compression, the steel fiber has little effect on the peak stress of SFRAC, and when the volume fraction of steel fiber is 1vol%, the improvement effect on the deformation performance of SFRAC is optimal. Finally, the formulas for calculating the peak stress, peak strain and elastic modulus of SFRAC under triaxial compression are put forward.
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表 1 钢纤维物理指标
Table 1. Physical indexes of steel fiber
Steel fiber Density/(g·cm−3) Length/mm Diameter/mm Aspect ratio Tensile strength/MPa 7.85 37 0.9 41.1 ≥1150 表 2 粗骨料物理性质
Table 2. Properties of coarse aggregate
Aggregate Water
absorption/%Moisture content/% Bulk density/(kg·m−3) Apparent density/(kg·m−3) Crush
index/%Size/mm NA 0.43 0.07 1499.9 2703.9 17.15 5-20 RA 5.35 1.55 1321.3 2599.6 25.63 5-20 Notes: NA—Natural coarse aggregate; RA—Recycled coarse aggregate. 表 3 混凝土配合比
Table 3. Mixture ratio of concrete
Strength grade γ/wt% C/(kg·m−3) S/(kg·m−3) NA/(kg·m−3) RA/(kg·m−3) W/(kg·m−3) Wa/(kg·m−3) C35 0 500 542 1153.0 0.0 215.0 0.0 C35 30 500 542 807.1 345.9 215.0 7.5 C35 50 500 542 576.5 576.5 215.0 12.5 C35 70 500 542 345.9 807.1 215.0 17.5 C35 100 500 542 0.0 1153.0 215.0 25.0 Notes: γ—Replacement rate of recycled coarse aggregate; C—Cement content; S—Sand content; NA—Natural coarse aggregate content; RA—Recycled coarse aggregate content; W—Water content; Wa—Additional water content. 表 4 钢纤维再生混凝土(SFRAC)试件参数设计
Table 4. Parameters of steel fiber recycled aggregate concrete (SFRAC) specimens
Specimen number γ/wt% Vs/vol% σw/MPa 1%SFRCA(0%)-0 MPa 0 1 0 1%SFRCA(0%)-3 MPa 0 1 3 1%SFRCA(0%)-6 MPa 0 1 6 1%SFRCA(0%)-9 MPa 0 1 9 1%SFRCA(0%)-15 MPa 0 1 15 1%SFRCA(0%)-21 MPa 0 1 21 1%SFRCA(0%)-27 MPa 0 1 27 1%SFRCA(30%)-0 MPa 30 1 0 1%SFRCA(30%)-3 MPa 30 1 3 1%SFRCA(30%)-6 MPa 30 1 6 1%SFRCA(30%)-9 MPa 30 1 9 1%SFRCA(30%)-15 MPa 30 1 15 1%SFRCA(30%)-21 MPa 30 1 21 1%SFRCA(30%)-27 MPa 30 1 27 1%SFRCA(50%)-0 MPa 50 1 0 1%SFRCA(50%)-3 MPa 50 1 3 1%SFRCA(50%)-6 MPa 50 1 6 1%SFRCA(50%)-9 MPa 50 1 9 1%SFRCA(50%)-15 MPa 50 1 15 1%SFRCA(50%)-21 MPa 50 1 21 1%SFRCA(50%)-27 MPa 50 1 27 1%SFRCA(70%)-0 MPa 70 1 0 1%SFRCA(70%)-3 MPa 70 1 3 1%SFRCA(70%)-6 MPa 70 1 6 1%SFRCA(70%)-9 MPa 70 1 9 1%SFRCA(70%)-15 MPa 70 1 15 1%SFRCA(70%)-21 MPa 70 1 21 1%SFRCA(70%)-27 MPa 70 1 27 1%SFRCA(100%)-0 MPa 100 1 0 1%SFRCA(100%)-3 MPa 100 1 3 1%SFRCA(100%)-6 MPa 100 1 6 1%SFRCA(100%)-9 MPa 100 1 9 1%SFRCA(100%)-15 MPa 100 1 15 1%SFRCA(100%)-21 MPa 100 1 21 1%SFRCA(100%)-27 MPa 100 1 27 0%SFRCA(100%)-0 MPa 100 0 0 0%SFRCA(100%)-3 MPa 100 0 3 0%SFRCA(100%)-6 MPa 100 0 6 0%SFRCA(100%)-9 MPa 100 0 9 0%SFRCA(100%)-15 MPa 100 0 15 0%SFRCA(100%)-21 MPa 100 0 21 0%SFRCA(100%)-27 MPa 100 0 27 0.5%SFRCA(100%)-0 MPa 100 0.5 0 0.5%SFRCA(100%)-3 MPa 100 0.5 3 0.5%SFRCA(100%)-6 MPa 100 0.5 6 0.5%SFRCA(100%)-9 MPa 100 0.5 9 0.5%SFRCA(100%)-15 MPa 100 0.5 15 0.5%SFRCA(100%)-21 MPa 100 0.5 21 0.5%SFRCA(100%)-27 MPa 100 0.5 27 1.5%SFRCA(100%)-0 MPa 100 1.5 0 1.5%SFRCA(100%)-3 MPa 100 1.5 3 1.5%SFRCA(100%)-6 MPa 100 1.5 6 1.5%SFRCA(100%)-9 MPa 100 1.5 9 1.5%SFRCA(100%)-15 MPa 100 1.5 15 1.5%SFRCA(100%)-21 MPa 100 1.5 21 1.5%SFRCA(100%)-27 MPa 100 1.5 27 Notes: Vs—Volume fraction of steel fiber; σw—Confining pressure. 表 5 钢纤维分散效果
Table 5. Dispersion effect of steel fiber
Volume fraction of steel fiber/vol% Group 1 Group 2 Group 3 Design value 1 1 1 Measured value 0.91 1.08 1.03 表 6 SFRAC特征点参数
Table 6. Characteristic point parameters of SFRAC
Specimen number σv/MPa εv/10−3 E/GPa 1%SFRCA(0%)-0 MPa 26.89 4.91 5.67 1%SFRCA(0%)-3 MPa 58.10 8.43 7.89 1%SFRCA(0%)-6 MPa 75.84 12.07 8.46 1%SFRCA(0%)-9 MPa 89.64 16.76 8.84 1%SFRCA(0%)-15 MPa 120.42 21.17 9.81 1%SFRCA(0%)-21 MPa 141.20 24.90 11.23 1%SFRCA(0%)-27 MPa 157.23 30.56 11.78 1%SFRCA(30%)-0 MPa 26.47 5.03 5.33 1%SFRCA(30%)-3 MPa 49.67 10.85 6.36 1%SFRCA(30%)-6 MPa 72.42 14.47 7.63 1%SFRCA(30%)-9 MPa 89.50 16.04 8.54 1%SFRCA(30%)-15 MPa 111.41 23.94 8.87 1%SFRCA(30%)-21 MPa 131.69 31.69 9.69 1%SFRCA(30%)-27 MPa 152.11 40.73 10.62 1%SFRCA(50%)-0 MPa 29.84 6.34 5.40 1%SFRCA(50%)-3 MPa 56.42 9.48 7.94 1%SFRCA(50%)-6 MPa 71.22 12.79 8.55 1%SFRCA(50%)-9 MPa 83.48 18.29 8.51 1%SFRCA(50%)-15 MPa 106.71 25.06 9.02 1%SFRCA(50%)-21 MPa 122.29 35.46 9.20 1%SFRCA(50%)-27 MPa 146.45 49.30 10.37 1%SFRCA(70%)-0 MPa 23.44 5.19 4.95 1%SFRCA(70%)-3 MPa 51.57 10.53 7.43 1%SFRCA(70%)-6 MPa 67.08 15.43 8.43 1%SFRCA(70%)-9 MPa 80.68 20.54 8.58 1%SFRCA(70%)-15 MPa 100.79 28.22 8.94 1%SFRCA(70%)-21 MPa 119.58 44.75 9.40 1%SFRCA(70%)-27 MPa 142.17 56.16 9.82 1%SFRCA(100%)-0 MPa 22.32 5.66 5.09 1%SFRCA(100%)-3 MPa 54.35 10.15 7.16 1%SFRCA(100%)-6 MPa 67.42 13.75 7.83 1%SFRCA(100%)-9 MPa 78.97 18.36 8.53 1%SFRCA(100%)-15 MPa 98.34 33.12 8.74 1%SFRCA(100%)-21 MPa 118.30 52.35 8.95 1%SFRCA(100%)-27 MPa 137.57 80.48 9.86 0%SFRCA(100%)-0 MPa 25.89 5.01 5.20 0%SFRCA(100%)-3 MPa 53.24 9.79 6.72 0%SFRCA(100%)-6 MPa 66.13 15.12 7.24 0%SFRCA(100%)-9 MPa 79.16 19.42 8.61 0%SFRCA(100%)-15 MPa 99.35 28.35 9.28 0%SFRCA(100%)-21 MPa 118.13 41.36 10.23 0%SFRCA(100%)-27 MPa 137.32 69.65 10.25 0.5%SFRCA(100%)-0 MPa 26.51 5.01 4.76 0.5%SFRCA(100%)-3 MPa 54.84 11.90 6.66 0.5%SFRCA(100%)-6 MPa 70.77 13.35 8.23 0.5%SFRCA(100%)-9 MPa 81.85 16.86 8.65 0.5%SFRCA(100%)-15 MPa 101.79 25.64 9.49 0.5%SFRCA(100%)-21 MPa 119.85 40.15 9.66 0.5%SFRCA(100%)-27 MPa 138.18 61.12 9.88 1.5%SFRCA(100%)-0 MPa 26.05 5.35 5.29 1.5%SFRCA(100%)-3 MPa 52.53 10.07 7.29 1.5%SFRCA(100%)-6 MPa 67.79 14.64 8.15 1.5%SFRCA(100%)-9 MPa 81.72 17.81 8.70 1.5%SFRCA(100%)-15 MPa 101.78 32.57 8.83 1.5%SFRCA(100%)-21 MPa 119.60 49.84 9.24 1.5%SFRCA(100%)-27 MPa 138.72 63.65 9.81 Notes: σv—Peak stress; εv—Peak strain; E—Elastic modulus. -
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