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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 81
PROCEEDINGS OF THE TENTH INTERNATIONAL CONFERENCE ON CIVIL, STRUCTURAL AND ENVIRONMENTAL ENGINEERING COMPUTING
Edited by: B.H.V. Topping
Paper 21

Study on the Mix Proportioning Design of Recycled Concrete by the Taguchi Method

Y.H. Lin+, Y.Y. Tyan* and P.C. Lee+

+Department of Construction Engineering, National Taiwan University of Science and Technology, Taiwan, R.O.C.
*Department of Civil Engineering, Chung Kuo Institute of Technology, Taiwan, R.O.C.

Full Bibliographic Reference for this paper
Y.H. Lin, Y.Y. Tyan, P.C. Lee, "Study on the Mix Proportioning Design of Recycled Concrete by the Taguchi Method", in B.H.V. Topping, (Editor), "Proceedings of the Tenth International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 21, 2005. doi:10.4203/ccp.81.21
Keywords: recycled concrete, mix proportioning design, Taguchi method.

Summary
There are about 7,260,000 m3/year (11,620,000 ton/year) of demolished debris from buildings in Taiwan [1], and the demolished and cracked concrete has a 60-85% (weight ratio) within the demolished debris. Recycling and re-use the building debris to help preserve natural resources, prevent environmental pollution and consider the cost-savings of construction projects, is an increasing trend in Taiwan.

According to past studies, using recycled concrete aggregates for backfill material, low-strength concrete, asphalt concrete pavements or rigid pavements has the highest economic importance [1,2,3]. The recycled concrete aggregates are made of crushed demolished concrete. The studies concerning recycled concrete, all showed that it is feasible to use the material, but there is a difference in mix proportioning [1,4,5,6]. In early studies, the recycled aggregates are usually made into a cylinder specimen in the laboratory, which are cleaner than the demolished concrete in the building field. Although this can reduce the size of the experiment and save cost, when the demolished concrete is unstable in quality, the test property is not unique and its influence factors have an interaction in practice. Consequently, this study is concentrated on the use of the science management method to investigate demolished aggregates that are used in recycled concrete and multi-characteristics and its interactions are considered.

The Taguchi method is an important technique of quality management [7]. The Taguchi method has been successfully applied to many materials; it can now be applied to the recycled concrete which is heterogeneous and has a complex chemical action.

The Taguchi method is a commonly used method to choose the control factors, investigate the interactions between influencing factors and design the experiment based on analysis of variance (ANOVA). This paper applies the Taguchi method to examine the interaction relationship between five control factors: the water/cement ratio, the volume ratio of recycled coarse aggregates, the replacement by river sand, the content of crushed brick and the cleanness of the aggregate. To demonstrate the effectiveness of the Taguchi method, a case study is used to select an optimal combination of recycled concrete based on the maximum reductions in time and cost. Under 95% confidence level, it is found that the optimal combination of the mix design of the recycled concrete is given by a 0.5 water/cement ratio, a 0.42 ratio of volume to recycled coarse aggregates, 100% river sand, 0% crushed brick, and clean aggregates.

References
1
Huang, Rong-Yau., "The framework about the present and survey of the population and debris from demolished building", Architecture and Building Research Institute, Taipei (1998.06)
2
Chen, Jen-Chuan, "The plan about driving to reuse demolished debris from building in 921 earthquake", Taiwan Construction Research Institute, Taipei (2000.03)
3
Chen, Jhao-Yun., "The feasibility about reusing the demolished debris into public engineering", Master thesis of National Central University (2000.06)
4
Ryu, J.S., "Improvement on strength and impermeability of recycled concrete made from crushed concrete coarse aggregate", Journal of Materials Science Letters, Vol. 21, No. 20, pp. 1565-1567 (2002.10) doi:10.1023/A:1020349011716
5
Corinaldesi V., Giuggiolini M., Moriconi G., "Use of rubble from building demolition in mortars", Waste Management, Vol. 22, No.8, pp. 893-899 (2002.12) doi:10.1016/S0956-053X(02)00087-9
6
Gomez-Soberon, and M.V. Jose., "Porosity of recycled concrete with substitution of recycled concrete aggregate: An experimental study", Cement and Concrete Research, Vol. 32, No.8, pp. 1301-1311 (2002.08) doi:10.1016/S0008-8846(02)00795-0
7
ISO, "ISO9000:2000 Quality Management System", International Organization for Standardization (2000)

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