مقاله انگلیسی رایگان در مورد تنوع و محتوای سنگدانه درشت زغال سنگ – الزویر 2019

Concrete were prepared by replacing natural gravel (N) with spontaneous combustion gangue (S) or rock gangue (R) at intervals of 25%. Mechanical tests were carried out and the microstructural features of the concrete were characterized. Failure modes and strength of different concrete are various, and the compressive strength of the concrete meets the design requirements of C30 strength grade concrete. The axial compression failure mode of R coarse aggregate concrete (RAC) was shear failure. As the S replacement percentage increased, the axial compression failure mode of S coarse aggregate concrete (SAC) transformed from shear failure to longitudinal splitting failure. The ITZ of SAC is the best; as the replacement percentage increased, the peak stress and slope of the rising section of the stress-strain curves of RAC and SAC decreased, and the peak strains increased. Finally, compressive stress-strain curve prediction models for coal gangue coarse aggregate concrete were suggested.

Introduction

China is a large country with coal as its main energy source. The annual output of coal gangue solid waste, which is produced during coal production, amounts to hundreds of millions of tons. A large amount of coal gangue is stored for a long time, and such storage can destroy the ecological balance and harm the environment. Statistics show that among the more than 2100 counties in China, extensive coal gangue accumulation has been reported in more than 1200 counties. Currently, the amount of accumulated coal gangue is approximately 4.5 billion tons, and there are more than 1600 coal gangue mounds that occupy approximately 15,000 ha of land; moreover, the quantity of gangue accumulation is increasing at a rate of 1.5–200 million tons per year [1,2]. With the rapid development of infrastructure construction in China, raw materials such as sand and stone, which are used in concrete, the most common engineering materials, must be urgently supplied. In the summer of 2018, the prices of sand and stone in the Pearl River Delta (China) area exceeded 300 RMB/ m3 , resulting in a price increase of 700 RMB/m3 for C30 ready-mixed concrete, which has caused panic in the industry [3,4].