Akademik Veri Yönetim Sistemi
Journal of Building Pathology and Rehabilitation, cilt.10, sa.1, 2025 (Scopus)
With the increase in the population of cities, the need for new constructions increases. In meeting this need, the recycling of buildings that are close to the end of their service life is a priority. When the quality of old buildings is examined, it is seen that the majority of them have low strength quality (< 20 MPa). Therefore, the use of demolition wastes with low concrete strength quality as recycled aggregate has a great potential to protect natural resources. In addition, the use of industrial wastes together with low-strength quality demolition wastes is an issue that needs to be investigated to produce more sustainable concrete. In this experimental study, cement was substituted with silica fume and fly ash mineral admixtures at 5% and 10% in concrete production. For coarse aggregates, recycled aggregates obtained from the demolition wastes of two buildings identified as risky within the scope of the Buyukcekmece Municipality Urban Transformation Project were used instead of those obtained from natural sources. The coarse aggregates obtained from these two separate buildings were divided into low (5 MPa) and intermediate (15 MPa) classes according to the strength of the source concrete and replaced with natural aggregates at 0%, 50%, and 100% to produce concrete mixes with no mineral additive, 5%, 10% mineral admixture. In order to investigate the reusability of recycled low and intermediate-strength aggregates obtained from construction demolition wastes in concrete production, mechanical tests such as compressive and splitting tensile strengths of concrete were determined on the 28th day. According to the test results, the fact that the aggregates obtained from low and intermediate strength quality are approximately the same value in terms of water absorption capacity (~ 7.5%) directly affected the concrete compressive strength and provided concrete production in the same strength class. According to the concrete compressive strength results of the series without mineral admixtures, the strength decreases as the RCA ratio increases, regardless of the parent concrete quality. Both strength quality classes without mineral admixtures successfully met the C30/37 concrete class at a 50% replacement ratio and the C20/25 concrete class at a 100% replacement ratio. This paper emphasizes that aggregates obtained from parent concrete with 5 MPa and 15 MPa strength can be considered in the same low-strength quality class and have similar properties in terms of use.