Guo Jinjun, Zhang Zheng, Wu Jingjiang, Wang Huikang, Zhang Peng, Wang Kun, Meng Qingxin, Xu Hongyin
School of Water Conservancy Engineering, Zhengzhou University, Zhengzhou 450001, China.
China Construction Seventh Engineering Division Co., Ltd., Zhengzhou 450001, China.
Materials (Basel). 2021 Sep 5;14(17):5085. doi: 10.3390/ma14175085.
The application of concrete containing mineral admixtures was attempted in Northwest China in this study, where the environment has the characteristics of low humidity and large temperature variation. The harsh environment was simulated by using an environmental chamber in the laboratory and four types of concrete were prepared, including ordinary concrete and three kinds of mineral admixture concretes with different contents of fly ash and blast-furnace slag. These concretes were cured in the environmental chamber according to the real curing conditions during construction. The compression strength, fracture properties, SEM images, air-void characteristics, and X-ray diffraction features were researched at the early ages of curing before 28 d. The results showed that the addition of fly ash and slag can improve the compression strength and fracture properties of concrete in the environment of low humidity and large temperature variation. The optimal mixing of mineral admixture was 10% fly ash and 20% slag by replacing the cement in concrete, which can improve the compression strength, initial fracture toughness, unstable fracture toughness, and fracture energy by 23.9%, 25.2%, 45.3%, and 22.6%, respectively, compared to ordinary concrete. Through the analysis of the microstructure of concrete, the addition of fly ash and slag can weaken the negative effects of the harsh environment of low humidity and large temperature variation on concrete microstructure and cement hydration.
本研究尝试在中国西北地区使用含矿物掺合料的混凝土，该地区环境具有低湿度和大温度变化的特点。在实验室中使用环境试验箱模拟恶劣环境，并制备了四种类型的混凝土，包括普通混凝土和三种不同粉煤灰和矿渣含量的矿物掺合料混凝土。这些混凝土根据施工期间的实际养护条件在环境试验箱中养护。在养护28天之前的早期龄期研究了抗压强度、断裂性能、扫描电镜图像、气孔特征和X射线衍射特征。结果表明，在低湿度和大温度变化的环境中，添加粉煤灰和矿渣可以提高混凝土的抗压强度和断裂性能。矿物掺合料的最佳配合比是用10%的粉煤灰和20%的矿渣替代混凝土中的水泥，与普通混凝土相比，可分别提高抗压强度、初始断裂韧性、失稳断裂韧性和断裂能23.9%、25.2%、45.3%和22.6%。通过对混凝土微观结构的分析，添加粉煤灰和矿渣可以减弱低湿度和大温度变化的恶劣环境对混凝土微观结构和水泥水化的负面影响。
