西安建筑科技大学学报(自然科学版)

寒区冻害是影响混凝土结构耐久性的重要因素.为揭示冻融循环作用下钢纤维煤矸石混凝土的抗冻性能及微观冻融机理,对棱柱体钢纤维煤矸石混凝土试样进行了冻融循环及SEM试验.结果表明:冻融导致素混凝土裂隙贯通且结构呈松散状,抗冻能力偏差.掺入钢纤维起到增强阻裂作用,抗冻能力明显提高.钢纤维煤矸石混凝土的质量损失率与冻融循环次数呈线性-指数函数增长.冻融效应对动弹模量的变化率具有劣化作用,动弹模量损失率呈线性衰减.劈拉强度随钢纤维体积率提高呈先增大后衰减变化,钢纤维体积率为2.00%的混凝土的强化作用明显低于0.50%～1.50%,钢纤维明显降低了混凝土的冻融损伤.随着冻融次数增大,素混凝土表层剥落显著,钢纤维混凝土未出现结构疏松现象.钢纤维限制了裂隙贯通,具有明显的增强阻裂作用.研究成果可为钢纤维煤矸石混凝土在寒区建筑工程中的应用提供参考.

Cold damage in cold area is an important factor affecting the durability of concrete structure. To reveal the freezing resistance and micro freezing mechanism of steel fiber gangue concrete under the freezing and thaw cycle, the freeze and thaw cycle and SEM testing of prismatic steel fiber gangue concrete sample were conducted. The results show that freezing and thawing lead to plain concrete crack through and loose structure. The mixed steel fiber plays the role of crack resistance, freezing resistance is significantly improved. The mass loss rate and the frequency of freeze-thaw cycle increase by linear-exponential function. The freeze-thaw effect degraded the change rate of moving modulus, and the loss rate shows linear decay. The split tensile strength increases with the increase of the steel fiber volume rate and then attenuates. The strengthening effect of the concrete with the steel fiber volume rate of 2.00% is obviously lower than 0.50%～1.50%, and the steel fiber obviously reduces the freeze-thawing damage of the concrete. With the increase of freeze-thaw effect, the surface peeling of plain concrete is obvious, and the steel fiber concrete does not appear loose structure. Steel fiber limits the crack penetration and has obvious enhanced crack resistance. The research results can provide a reference for the application of steel fiber coal gangue concrete in construction engineering in cold area.

引言
1 试验概述
2 结果与分析
3 结论

图1 水泥及钢纤维<br/>Fig.1 Cement and steel fiber

图1 水泥及钢纤维
Fig.1 Cement and steel fiber

表1 P.O42.5R普通硅酸盐水泥的性能指标<br/>Tab.1 Performance index of P.O42.5R ordinary portland cement

表1 P.O42.5R普通硅酸盐水泥的性能指标
Tab.1 Performance index of P.O42.5R ordinary portland cement

图2 钢纤维煤矸石混凝土试样<br/>Fig.2 Test sample of steel-fiber coal-gangue concrete

图2 钢纤维煤矸石混凝土试样
Fig.2 Test sample of steel-fiber coal-gangue concrete

表2 混凝土配合比及劈拉强度<br/>Tab.2 Mix ratio and tensile strength of concrete

表2 混凝土配合比及劈拉强度
Tab.2 Mix ratio and tensile strength of concrete

图3 钢纤维体积率对质量损失率的影响<br/>Fig.3 Effect of the steel fiber volume rate on the mass loss rate

图3 钢纤维体积率对质量损失率的影响
Fig.3 Effect of the steel fiber volume rate on the mass loss rate

图4 钢纤维煤矸石混凝土试样表面的冻融损伤形态<br/>Fig.4 Frozen-thaw damage form of sample surface of steel-fiber coal-gangue concrete

图4 钢纤维煤矸石混凝土试样表面的冻融损伤形态
Fig.4 Frozen-thaw damage form of sample surface of steel-fiber coal-gangue concrete

图5 钢纤维体积率对动弹模量损失率的影响<br/>Fig.5 Effect of steel fiber volume rate on loss rate of dynamic elastic modulus

图5 钢纤维体积率对动弹模量损失率的影响
Fig.5 Effect of steel fiber volume rate on loss rate of dynamic elastic modulus

图6 钢纤维体积率对承载强度的影响<br/>Fig.6 Effect of steel fiber volume rate on the bearing strength

图6 钢纤维体积率对承载强度的影响
Fig.6 Effect of steel fiber volume rate on the bearing strength

图7 钢纤维煤矸石混凝土内部界面过渡区SEM图像<br/>Fig.7 SEM image of the internal interface transition area of steel-fiber coal-gangue concrete

图7 钢纤维煤矸石混凝土内部界面过渡区SEM图像
Fig.7 SEM image of the internal interface transition area of steel-fiber coal-gangue concrete

图8 素混凝土(B1)冻融循环后的SEM图像<br/>Fig.8 SEM image after the freeze-thaw cycle of plain concrete(B1)

图8 素混凝土(B1)冻融循环后的SEM图像
Fig.8 SEM image after the freeze-thaw cycle of plain concrete(B1)

图9 钢纤维煤矸石混凝土(B4)冻融循环后的SEM图像<br/>Fig.9 SEM image after the freeze-thaw cycle of steel-fiber coal-gangue concrete(B4)

图9 钢纤维煤矸石混凝土(B4)冻融循环后的SEM图像
Fig.9 SEM image after the freeze-thaw cycle of steel-fiber coal-gangue concrete(B4)

图10 钢纤维煤矸石混凝土(B5)冻融循环后的SEM图像<br/>Fig.10 SEM image after the freeze-thaw cycle of steel-fiber coal-gangue concrete(B5)

图10 钢纤维煤矸石混凝土(B5)冻融循环后的SEM图像
Fig.10 SEM image after the freeze-thaw cycle of steel-fiber coal-gangue concrete(B5)

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备注

引言

1 试验概述

2 结果与分析

3 结论

期刊信息