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The use of recycled concrete aggregate for concrete production incorporating calcined clay as pozzolanic admixture

Olofinnade, O. M. and Oyawoye, I. T. and Ogara, J. I. and Ede, A. N. and Ndambuki, J.M. and Akinwumi, I. I. and Ajao, Adekunle M (2019) The use of recycled concrete aggregate for concrete production incorporating calcined clay as pozzolanic admixture. In: 1st International Conference on Sustainable Infrastructural Development, 2019.

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Concrete is the most widely used construction material thereby required a lot of raw resources to keep up with its demand. This leads to depletion of raw resources as well as a continuous build-up of demolished concrete wastes (DCW). In most developing nations like Nigeria, the usual way of disposing these DCW is landfilling. However, recycling has become a viable options for conserving the raw resources and reducing greenhouse gases. This study examines the alternative way of reusing concrete wastes for production of fresh structural concrete. The DCW was obtained from the demolition of an existing concrete building and were treated by soaking in water to help reduce the amount of adhered mortar. A mix ratio of 1:1:2 was adopted with a water-cement ratio of 0.25 to attain a relatively high strength concrete and superplasticizer was added to ensure workable mixes. The recycled aggregates (RCA) were used as partial and complete substitute for natural coarse aggregates in percentages of 0, 20, 40, 60, 80 and 100%, while calcined clay was added as pozzolanic admixture into the mixes at 15% and 20% partial replacement for cement. Tests carried out include the physical characterization of the constituent materials and the compressive strength of the hardened concretes were determined after 7, 14 and 28 days of curing in water using cubes of 100 mm × 100 mm × 100 mm. Results showed that the recycled concrete aggregates has high water absorption due to its porous interface. Moreso, results clearly indicate a continual decreasing trend in the compressive strength as the percentages of the RCA increases, however, a significant increase in compressive strength was observed when calcined clay was added as substitute for cement thereby improving the strength development of concrete.

Item Type: Conference or Workshop Item (Paper)
Uncontrolled Keywords: Recycled concrete aggregate, Natural coarse aggregate, compressive strength, Sustainability
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
T Technology > TH Building construction
Divisions: Faculty of Engineering, Science and Mathematics > School of Civil Engineering and the Environment
Depositing User: Dr Oluwarotimi Michael Olofinnade
Date Deposited: 19 May 2021 09:15
Last Modified: 19 May 2021 09:15

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