Abstract
In this study, the effects of recycled sand (RS) carrying sulfate corrosion media on mortar drying and autogenous shrinkages were investigated. Four variables were considered, the replacement percentage of RS, water to cement (W/C) ratio, secondary cementitious material, and the corrosion concentration of RS. The test results indicated that the replacement percentage of RS was positively related to the drying and autogenous shrinkages of the mortar. The drying shrinkage of the mortar increased with an increase in the W/C ratio, while the autogenous shrinkage showed an opposite trend. The addition of fly ash (FA) had a significant inhibitory effect on the drying and autogenous shrinkages of the mortar. The drying shrinkage of the mortar was reduced, while the autogenous shrinkage was increased by adding granulated blast-furnace slag (GBFS). The addition of both FA and GBFS caused an increase in the autogenous shrinkage. As the corrosion concentration of RS increased, the drying and autogenous shrinkage values decreased slightly. The scanning electron microscopy and X-ray diffraction analysis results showed that the corrosion products formed by the reaction of sulfate ions carried by RS and cement hydration products filled the internal pores of the mortar and slowed down the shrinkage of the mortar.
Highlights
We aim to investigate the effect of recycled sand (RS) carrying sulfate corrosion media on drying and autogenous mortar shrinkage, in terms of the replacement percentage of RS, water to cement (W/C) ratio, secondary cementitious material, and the corrosion concentration of RS
As the curing age increased, the shrinkage of the mortar was inhibited by swelling corrosion products that were formed by the reaction of sulfate corrosion media carried by RS and the hydration products
As compared with the reference mortar, the drying shrinkage of the mortar with the RS replacement percentages of 20%, 50%, and 100% increased by 14.4%, 26.5%, and 50.8% at 3 d, respectively, while the corresponding replacement percentage at 14 d increased by 10.8%, 19.3%, and 34.0%, respectively
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The utilization of construction waste has become an important issue worldwide. According to statistics from the Chinese Academy of Sciences, about. 2.4 billion tons of construction waste are generated annually [1]. Relevant regulations have been promulgated to vigorously develop the classification and utilization of construction waste. Under the regulations carried out in China, various studies have been conducted on the recycling of the construction waste. The method of partially or completely replacing natural aggregates with recycled aggregates (RAs) to prepare recycled concrete has been widely regarded as an effective approach [2,3,4,5]
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