Effect of Fly Ash with Different Particle Size Distributions on the Properties and Microstructure of Concrete
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JMEPEG https://doi.org/10.1007/s11665-020-05108-x
Effect of Fly Ash with Different Particle Size Distributions on the Properties and Microstructure of Concrete Yunpeng Cui, Jun Liu, Licheng Wang, Runqing Liu, and Bo Pang (Submitted June 21, 2020; in revised form August 19, 2020) Fly ash has become an important component of concrete as a supplementary cementitious material. Fly ash, as an admixture in concrete, has a great impact on the improvement of concrete properties and utilization of resources. In this work, fly ashes with different particle size distributions (S. Tsivilis, Andersen, normal and F distributions) were selected to prepare concrete. The relationships among the particle size distribution of the fly ash, compressive strength, hydration, pore structure and microstructure of the concrete were studied. The results showed that the compressive strength of the concrete increased at 28 d with fly ashes with the S. Tsivilis and F distributions. Moreover, the porosity of the concrete at 28 d was reduced, and the pore structure of the concrete was improved. The early compressive strength of the concrete increased with the fly ash with a normal distribution. The second hydration heat release rate of the concrete with fly ashes with a normal distribution and an F distribution was obviously faster. In addition to the Andersen distribution, other distributions of fly ash had obvious improvement effects on the pore structure of the concretes. High-performance concrete can be made from fly ash with different particle sizes, which avoids the need for ultrafine grinding with a high energy consumption and high-cost chemical excitation processes. Keywords
compressive strength, concrete, different particle sizes, fly ash
1. Introduction At present, it is well known that concrete is the most extensively used building material in the world (Ref 1-3). The development trend of building materials is to realize diversification, use green processes and provide a high performance. To reduce energy consumption and realize sustainable development, building materials should use a small amount of cement and a large amount of admixtures (Ref 4). There are studies about the effects of different admixtures on cement, especially industrial waste products (Ref 5). Fly ash is usually produced by the combustion of pulverized coal in power plants and is recovered by means of tools at the flue mouth. The color of fly ash particles is white or gray, and the appearance is spherical and smooth when observed with scanning electron microscope (SEM). The fluidity of cement can be adjusted by adding fly ash due to the microstructure of the fly ash. The composition and properties of fly ash mainly depend on the combustion conditions of the coal, the composition of the coal itself and the treatment of the fly ash after combustion. The specific surface area of fly ash ranges from 2900 to 4000 cm2/g, and the average particle size ranges from 8 to 20 lm. Fly ash is mainly composed of SiO2, Al2O3, Fe2O3 and CaO. Due to the
Yunpeng Cui, Licheng Wang, and Bo Pang, Facult
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