Assessing long-term (3-year) mechanical properties of recycled aggregate concrete containing zeolite and silica fume

Articles in Press

Document Type : Research Note

Authors

1 Faculty of Civil Engineering, University of Tehran

2 Faculty of Civil Engineering, College of Engineering, University of Tehran

Abstract

Using recycled concrete aggregate as a sustainable solution has been the subject of much research in recent years. The use of recycled aggregate has led to a reduction in the quality of concrete in various studies. A promising approach to enhance the concrete properties of recycled aggregate concrete involves the use of pozzolans as supplementary cementitious materials. In this study, cement was replaced by silica fume in 8% of the specimens, while in other specimens, cement was replaced by zeolite in 15%. Natural aggregate was substituted with recycled concrete aggregate in varying proportions of 30%, 50%, and 100%. Subsequently, various mechanical and durability tests were conducted to evaluate the properties of each specimen. Compressive and tensile tests were carried out to assess the mechanical properties of the specimens. The tests revealed that specimens containing recycled aggregate exhibited inferior properties compared to natural aggregate concrete. Over the long term (3 years), the specimens containing recycled aggregate also displayed lower compressive strength. Specimens containing silica fume demonstrated higher compressive strength in the short term when used with natural aggregate concrete, but showed similar performance over the 3-year period. In specimens containing recycled aggregate, silica fume had a more pronounced effect, leading to higher compressive strength in the short term but similar or reduced strength over the 3-year period. A similar trend to that observed in compressive strength was found in splitting tensile strength. As the percentage of recycled aggregate replacement increased, tensile strength decreased. The use of silica fume increased splitting tensile strength, even over the 3-year period. On the other hand, using zeolite did not result in a significant change, and specimens exhibited similar or reduced compressive strength over the 3-year period. In general, it can be inferred that the use of supplementary cementitious materials can enhance mechanical properties in the short term. However, durability tests, including water penetration depth and water absorption percentage, demonstrated almost the opposite trend. This suggests that the use of supplementary cementitious materials generally has a negative impact on concrete properties in the long term.

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Sharif Journal of Civil Engineering

Articles in Press, Accepted Manuscript
Available Online from 20 December 2024

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