Feasibility study of using recycled fresh concrete waste as coarse aggregates in concrete

Abstract In Hong Kong, a large amount of fresh concrete waste (FCW) is generated from ready mix concrete plants every day. Up to now, these wastes are usually delivered to landfills for disposal. The landfill areas in Hong Kong will be saturated in 6–8 years, as a result there is a need to develop a new technique for utilizing the FCW. In this study, FCW was crushed into coarse aggregate, and then it was used to replace natural coarse granite at percentages of 0%, 15%, 30% and 50%, in producing new concrete mixes. The concrete were produced with water/cement ratios of 0.35 and 0.50. The effect of using the normal mixing approach and the two-stage mixing approach on the properties of concrete was also compared. The results indicated that the density, strength and static modulus of elasticity of new concrete were decreased with an increase in FCW content. Due to the lower density and higher water absorption of FCW, the water absorption, chloride ion permeability and dry shrinkage of the new concrete was increased with the increase in FCW content. Moreover, the two-stage mixing approach (TSMA) only improved the strength of the FCW concrete when the concrete was prepared with a lower water-to-cement of 0.35. The results demonstrated that the FCW can be used to replace natural aggregates for the production of non-structural concrete.

[1]  Rómel G. Solís-Carcaño,et al.  Evaluation of concrete made with crushed limestone aggregate based on ultrasonic pulse velocity , 2008 .

[2]  C. Tam,et al.  Microstructural analysis of recycled aggregate concrete produced from two-stage mixing approach , 2005 .

[3]  Wfk Fong,et al.  HONG KONG EXPERIENCE OF USING RECYCLED AGGREGATES FROM CONSTRUCTION AND DEMOLITION MATERIALS IN READY MIX CONCRETE , 2004 .

[4]  I. Wernick,et al.  Modeling materials flow of waste concrete from construction and demolition wastes in Taiwan , 2002 .

[5]  Vivian W. Y Tam,et al.  Diversifying two-stage mixing approach (TSMA) for recycled aggregate concrete: TSMAs and TSMAsc , 2008 .

[6]  C. Poon,et al.  USE OF RECYCLED AGGREGATES IN MOLDED CONCRETE BRICKS AND BLOCKS , 2002 .

[7]  Yiching Lin,et al.  Investigation of Pulse Velocity-Strength Relationship of Hardened Concrete , 2007 .

[8]  I. Topcu,et al.  Properties of concretes produced with waste concrete aggregate , 2004 .

[9]  David A. Lange,et al.  Internal relative humidity and drying stress gradients in concrete , 2006 .

[10]  B. González-Fonteboa,et al.  Concretes with aggregates from demolition waste and silica fume. Materials and mechanical properties , 2008 .

[11]  K. M. Yusof,et al.  A combined ultrasound method applied to high performance concrete with silica fume , 2010 .

[12]  Fouad M. Khalaf,et al.  Recycling of Demolished Masonry Rubble as Coarse Aggregate in Concrete: Review , 2004 .

[13]  Chi Sun Poon,et al.  The use of recycled aggregate in concrete in Hong Kong , 2007 .

[14]  James C. Wang.  Young's modulus of porous materials , 1984 .

[15]  Nobuaki Otsuki,et al.  Influence of Recycled Aggregate on Interfacial Transition Zone, Strength, Chloride Penetration and Carbonation of Concrete , 2003 .

[16]  S. Tsimas,et al.  USE OF CONSTRUCTION AND DEMOLITION WASTES AS RAW MATERIALS IN CEMENT CLINKER PRODUCTION , 2006 .

[17]  Chi S. Poon.  MANAGEMENT AND RECYCLING OF DEMOLITION WASTE IN HONG KONG , 1997 .

[18]  S L Correia,et al.  Assessment of the recycling potential of fresh concrete waste using a factorial design of experiments. , 2009, Waste management.

[19]  Ni-Bin Chang,et al.  Recycling of construction and demolition waste via a mechanical sorting process , 2002 .