Table of Contents
Journal of Waste Management
Volume 2013, Article ID 394912, 10 pages
Research Article

Utilization of Six Sigma in Quality Improvement of Recycled Aggregates Concrete

1Civil Engineering Department, Kuwait University, P.O. Box 5969, Safat 13060, Kuwait
2Goldmark Consultants, 12211 Old Shelbyville Road, Louisville, KY 40243, USA

Received 5 September 2013; Accepted 2 October 2013

Academic Editor: Chihpin Huang

Copyright © 2013 Mohamad Terro et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The use of recycled demolished concrete in producing new concrete is an established method to improve sustainability through reducing the environmental impact of using virgin aggregates and through reducing construction waste. Six sigma is a set of tools and strategies for process improvement. In this paper, the six sigma DMAIC methodology is utilized to optimize the design parameters in order to improve and assure the quality of the resulting recycled aggregate concrete. The project aims to produce concrete with compressive strength of 25 MPa without using additives. Five parameters were used in the initial analysis that were reduced to three after refinement. The refined parameters are the ratio of recycled coarse aggregates, the ratio of recycled fine aggregates, and the water/cement ratio. It was concluded that the optimum values for the three parameters are 26%, 30%, and 0.5, in order.