Investigation of mechanical behavior of fibrous concrete containing pumice and metakaolin and chemical resistance to acid attack

Document Type : Research Article

Authors

1 Assistant professor - Faculty of Civil, Water and Environmental Engineering, Shahid Beheshti University, Tehran, Iran.

2 PhD student - Faculty of Civil, Water and Environmental Engineering, Shahid Beheshti University, Tehran, Iran.

3 Research and Development Service, Imen Rah Consulting Engineering Co., No7, 4th.St Khaled Eslamboli (Vozara) Ave. Tehran, Iran.

Abstract

Using fibers to reduce cracks and increase the joint spacing of concrete slabs has become popular in the concrete pavements of airports and freeways recently. However, their durability behavior against acid rain has been less studied. The purpose of this paper is to investigate the mechanical performance and durability of concrete reinforced with polyolefin and polypropylene fibers containing 15% of pozzolanic materials (pumice or metakaolin) instead of Portland type II cement. In this regard, compressive and flexural strength were measured to investigate the mechanical behavior of the studied mixtures at different ages. On the other hand, chemical resistance against acid rain simulated was investigated through the visual examination and weight loss, and also microstructural analysis was performed by SEM analysis and CT scan testing. Based on these results, the addition of both of these fibers in concrete reduces the compressive strength of concretes compared to the similar content in the control concrete. On the contrary, fibers increased the flexural strength, which became much more significant with the addition of pozzolanic materials. However, ordinary and fibrous concrete containing pozzolanic materials showed a weak performance against acid rain. Based on the results of CT scan and SEM analysis, concretes containing pozzolanic materials have a porous structure. Besides, the ratio of calcium to silicon in them is much lower than the control concrete due to decalcification reactions caused by acid attacks.

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