冻结井壁仿钢纤维混凝土动静态力学性能和微观结构研究

摘要/Abstract

摘要： 为改善冻结井壁高强混凝土脆性特征,提高其抗裂性和韧性,提出采用仿钢纤维混凝土作为冻结井壁筑壁材料。通过优选材料和正交试验,得到不同配合比的仿钢纤维高性能井壁混凝土,并对其进行静态、动态力学性能及微观结构等试验研究。结果表明,在基准混凝土中掺入15%(质量分数)粉煤灰和0.54%(体积分数)聚丙烯仿钢纤维(PPTF)后,混凝土的抗拉、抗弯强度分别提高了29.46%、26.72%,其脆性特征得以明显提高。相比于基准组,最佳配合比的仿钢纤维混凝土韧性增强显著,在0~0.012应变范围内其韧性指数提高了40.83%,且失效后的破坏形态更完整。掺入PPTF、粉煤灰有效抑制了冻结井壁混凝土内部微裂隙的产生和扩张,混凝土表现出更为致密的微观结构以及更高的宏观力学性能。

关键词: 井壁混凝土, 仿钢纤维, 正交试验, 强度, 动态力学, 微观结构

Abstract: In order to improve the brittleness characteristics of high-strength concrete in frozen shaft lining, and improve its crack resistance and toughness, the imitation steel fiber reinforced concrete was proposed as lining building material of frozen shaft lining. Through the optimization of materials and orthogonal tests, theimitation steel fiber reinforced high-performance concrete with different mixing ratios was obtained, and the static and dynamic mechanical properties and microstructure were experimentally studied. The results show that the tensile and flexural strength of concrete is increased by 29.46% and 26.72%, and its brittle characteristics are significantly improved by adding 15% (mass fraction) fly ash and 0.54% (volume fraction) polypropylene imitation steel fiber (PPTF) to the benchmark concrete. Compared with the benchmark group, the toughness of imitation steel fiber reinforced concrete with the best mix ratio is significantly enhanced, the toughness index increases by 40.83% in the strain range of 0~0.012, and the failure patterns after failure is more complete. The addition of PPTF and fly ash effectively inhibits the generation and expansion of micro-cracks in frozen shaft lining concrete, and the concrete shows a denser microstructure and higher macroscopic mechanical properties.

Key words: shaft lining concrete, imitation steel fiber, orthogonal test, strength, dynamic mechanics, microstructure

中图分类号:

TU528
TD262

王瑞, 姚直书, 方玉, 王佳奇. 冻结井壁仿钢纤维混凝土动静态力学性能和微观结构研究[J]. 硅酸盐通报, 2024, 43(8): 2835-2847.

WANG Rui, YAO Zhishu, FANG Yu, WANG Jiaqi. Dynamic and Static Mechanical Properties and Microstructure of Frozen Shaft Lining Imitation Steel Fiber Reinforced Concrete[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2024, 43(8): 2835-2847.

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