摘要:
为实现煤矸石的高效利用，制作可直接用于矿井巷道地面的煤矸石混凝土，以煤矸石取代天然粗骨料的取代率、水灰比大小、外加剂掺量为影响因素，通过三因素三水平正交设计的方法对C20、C30、C40三种强度煤矸石混凝土的力学性能进行试验研究，探索各因素对煤矸石混凝土立方体试验试件的力学性能影响机制。结果表明：煤矸石取代率对混凝土立方体抗压强度的影响最大，对于C20、C30、C40三种强度等级的煤矸石混凝土，取代率为80%的28 d混凝土立方体抗压强度分别为取代率为0时的64.1%、63.4%、62.2%，而取代率为100%的28 d混凝土立方体抗压强度分别为取代率为0时的53.0%、56.8%、61.5%，与天然骨料混凝土相比，煤矸石骨料混凝土力学性能较弱，总体上强度偏低；对7、28 d两种龄期，取代率分别为80%和100%的煤矸石混凝土的立方体抗压强度和轴心抗压强度进行回归分析，得到的结果与现行国家规范中对普通混凝土的要求相近，表明取代率为80%和100%的煤矸石混凝土轴心抗压强度能够满足要求；由于煤矸石骨料自身力学性能较差，导致煤矸石混凝土劈裂强度不能达到规范要求，弹性模量明显低于普通混凝土，泊松比试验值离散性较大，变化规律不明显。基于试验结果，确定陕北矿业公司柠条塔煤矿巷道地坪C20级强度煤矸石混凝土最佳配比为：煤矸石取代率为100%、水胶比为0.45、不掺加减水剂，即水泥、水、黄砂、煤矸石质量比为1∶0.45∶1.31∶2.67。
关键词:
-
煤矸石
/
-
混凝土
/
-
力学性能
/
-
正交设计
/
-
配合比
/
-
特细砂
Abstract:
In order to realize the efficient use of coal gangue, making coal gangue concrete that can be directly used on the ground of mine roadways, the horizontal orthogonal design method was used to conduct experimental research on the mechanical properties of coal gangue concrete with three strengths of C20, C30 and C40, and to explore the influence mechanism of various factors on the mechanical properties of coal gangue concrete cube test specimens. The results show that the coal gangue replacement rate has the greatest impact on the compressive strength of the concrete cubes. For coal gangue concrete of C20, C30 and C40 strength grades, the compressive strength of the 28 d concrete cube with a replacement rate of 80% is 64.1%, 63.4%, and 62.2% when the replacement rate is 0, and the compressive strength of the 28 d concrete cube with a replacement rate of 100% is 53.0%, 56.8%, 61.5% respectively when the substitution rate is 0. Compared with those of natural aggregate concrete, coal gangue aggregate concrete has poor mechanical properties, and overall strength is low. Regression analysis was carried out on the cubic compressive strength and axial compressive strength of coal gangue concrete with replacement rates of 80% and 100% at 7 d and 28 d. The results obtained are similar to the requirements for ordinary concrete in the current national standards, indicating that the axial compressive strength of coal gangue concrete with replacement rates of 80% and 100% can meet the requirements. The performance is poor, so that the splitting strength of coal gangue concrete cannot meet the requirements of the specification, the elastic modulus is significantly lower than that of ordinary concrete, the Poisson’s ratio test value has a large dispersion, and the change rule is not obvious. Based on the test results, it is determined that the optimal ratio of C20 grade strength coal gangue concrete in roadway floor of Ningtiaota Coal Mine of Shanbei Mining Company is determined as follows: coal gangue replacement rate is 100%, water-binder ratio is 0.45, and no water reducing agent is added, that is, the mass ratio of cement, water, yellow sand and coal gangue is 1∶0.45∶1.31∶2.67.
百度学术
下载:
