The Study on the Whole Stress-Strain Curves of Coral Fly Ash-Slag Alkali-Activated Concrete under Uniaxial Compression.

Huailiang Wang,Lei Li,Yuhu Wei,Lang Wang,Yonggang Zhang,Baoquan Cheng

doi:10.3390/ma13194291

Abstract

This study aimed to research the whole stress–strain curves of coral Fly Ash-Slag Alkali-Activated Concrete (CAAC) in different strength grades. Fly ash-slag alkali-activated concrete was used as cementing materials to produce coral aggregate concrete. A monotonic loading test was conducted on the prismatic specimens to obtain elastic modulus (Ec), Poisson’s ratio (μ) and the constitutive relationship of CAAC under uniaxial compression. When the strain of CAAC reached the maximum value, the specimen was split and damaged rapidly. As the strength grade increased, the ratio of residual stress (σri) to peak stress (σ0i) decreased in the range of 0.17–0.28. The Ec of CAAC increased gradually, and μ increased to the peak value and then decreased. According to the test results, the constitutive equation of CAAC can be expressed by piecewise expression, which can better reflect all the experimental characteristics. It was also found that CAAC has many similar characteristics with coral concrete and lightweight aggregate concrete. To improve the strength and toughness of CAAC, some fibers, such as organic fiber, can be added to expand the application of CAAC in engineering projects.

Highlights

In recent years, with the rapid development of urban construction, the amount of cement used worldwide has surged
Brittleness is the main cause of coral Fly Ash-Slag Alkali-Activated Concrete (CAAC) uniaxial compression damage
The CAAC would be divided into multiple cylinders as a splitting failure

Summary

Introduction

With the rapid development of urban construction, the amount of cement used worldwide has surged. At the end of the last century, the global cement consumption exceeded. 2.2 billion tons per year [1]. According to Elchalakani [2], the production of ordinary Portland cement reached 3.7 billion tons in 2017, which was accompanied by 3 billion tons of CO2 emissions, accounting for about 7% of the total global emissions. Statistics released by the European Cement Association [3]. Showed that the cement output of the European Union was about 170 million tons in 2016, making it one of the major cement producers in the world. Materials 2020, 13, 4291 cement, exceeding 2.4 billion tons. From 2015 to 2016, Australia’s cement output was nearly 10 million tons, up 5% year on year [4]. Hao et al [5] and Cheng et al [6] reported that concrete is one of the most important sources of environmental impacts caused by construction activities

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