Abstract
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.
Highlights
In the past three decades, the economy of China developed rapidly
The results showed that fly ash and granulated blast furnace slag significantly increased the workability and compression strength of self-compacting concrete mixtures, and the best resistance to sodium and magnesium sulphate attacks was obtained from a combination of 40% granulated blast furnace slag with 60% cement
The early-age compression strengths of the four types of concrete were displayed in Figure 4, which all increased with the growth of the curing age
Summary
In the past three decades, the economy of China developed rapidly. In 2019, China’sGDP reach USD 14.343 trillion, ranking second in the world. China has accelerated the pace of infrastructure construction in the Northwest. From 2015 to 2019, China’s road construction investment had increased by 32.6%. In 2019, China completed CNY 10,049.8 billion in road construction investment in the Northwest [1]. There is a big difference in temperature between day and night, with daily temperature varying by more than 40 ◦C. It is dry and rainless in this region, and the air humidity is low. These harsh environmental characteristics have brought serious challenges to infrastructure construction, especially for concrete materials, which are commonly used in construction
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