Hazır Beton Santrallerinde Oluşan Çamur ve Atıksuyun Tekrar Kullanımı

Abstract

In this study, possibility of reuse of aggregate and recycled water as sludge and wastewater collected from ready-mixed concrete plants and unused concrete and sedimentation pools were investigated. It is demanded that the ready-mixed concrete industry show similar results and consistency in the quality tests made on the same class concrete, fresh concrete and hardened concrete produced at different times. For this reason, in order to be able to use the recycling aggregate continuously in the production of concrete and to obtain the same quality results in the concrete tests, the recycling aggregate obtained by washing and sifting the waste concrete and concrete slurry in the work carried out, the concentration of water collected in the sedimentation pool was diluted with mains water and fixed to 1.04 g/cm3 and reused in production. Concrete samples belonging to C25/30 and C30/37 compressive strength classes were prepared in two different cities using natural aggregate-recycling aggregate mixture and tests were made on concrete samples within the framework of standards determined by Turkish Standards Institute. In the study, it is found that the natural aggregate water absorption ratios are in the range of 0.21-2.50% while the recycling aggregate water absorption ratios have high rates in the range of 5-10%, and the specific gravity of recycle aggregates is 15% lower than the natural aggregates. In the abrasion resistance tests of the recycled coarse aggregates, the Los Angeles coefficient ratios were found to be 30% higher than the natural aggregates and the recycling aggregates' resistance to abrasion was lower. In fresh concrete tests, it is determined that the unit weight of concrete samples produced by recycling aggregate are lower by 0.65-0.70 kg/dm3 than the witness concrete samples, and the slump values are 7-16% lower than the witness concrete sample. In compressive strength tests made on hardened concrete specimens; in the case of C25/30 class concrete produced in the 1st plant, the 28 day compressive strength value was 30.2 MPa and the 30 MPa limit value was provided. In the C30/37 class concrete, the 28 day compressive strength value was measured as 37 MPa and it was found to provide 37 MPa limit value. It is determined that results of compressive strength tests of concrete specimens produced in the facility 2 are close to the limit values but did not provide the limit values. It has been determined that all of the wastewater generated in the concrete plants can be used continuously in the production process after being subjected to the washing and screening processes of the recycling aggregate.