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Ho N.Y.,Samwoh Corporation Pte Ltd | Lee Y.P.K.,Samwoh Corporation Pte Ltd | Lim W.F.,Samwoh Corporation Pte Ltd | Zayed T.,Nanyang Technological University | And 3 more authors.
Journal of Materials in Civil Engineering | Year: 2013

In Singapore, the applications of recycled concrete aggregate (RCA) are limited to nonstructural concrete, road construction, and backfilling. To realize the beneficial use of RCA, an in-depth study was conducted to evaluate its use in structural concrete. This paper reports the test results of a study that is part of extensive research intended to evaluate the properties of RCA concrete produced by a proposed rational approach in concrete mix design. The key parameters studied include compressive strength, elastic modulus,and drying shrinkage. The results showed that the RCA concrete can be designed to achievecomparable compressive strength and elastic modulus, relative to the corresponding properties of concrete containing natural coarse aggregate (NCA). RCA concrete tends to exhibithigher drying shrinkage strains relative to NCA concrete, but the values are within the recommended limits. © 2012 American Society of Civil Engineers.

Ho N.Y.,Samwoh Corporation Pte Ltd | Lee Y.P.K.,Samwoh Corporation Pte Ltd | Lim W.F.,Samwoh Corporation Pte Ltd | Chew K.C.,Building and Construction Authority Academy | And 2 more authors.
Magazine of Concrete Research | Year: 2015

This paper describes a study conducted to evaluate the use of concrete containing up to 100% recycled concrete aggregate (RCA) for the construction of a commercial building known as the Samwoh Eco-Green Building in Singapore. The study is a continuation of research which established that concrete produced with RCA can achieve strength comparable to that of normal concrete produced with natural aggregate for structural applications by using a rational mix design approach. The present study was carried out to evaluate the effects of RCA on other engineering and durability properties of concrete, including compressive strength, flexural strength, tensile splitting strength, creep strain, water permeability, initial surface absorption, chloride ingress and sulfate resistance. With normal concrete serving as the basis for comparison, the experimental data showed that comparable compressive strength, flexural strength and tensile splitting strength were attainable for concrete containing up to 100% RCA. Although concrete with 100% RCA exhibited higher creep strain and initial surface absorption rate as well as lower resistance to water permeability, chloride ingress and external sulfate attack, the effects on the concrete performance are insignificant. On the whole, the research study suggests that RCA concrete can be designed to meet the specifications for structural applications, which led to the successful completion of the Samwoh Eco-Green Building.

Ho N.Y.,Samwoh Corporation Pte Ltd | Lee Y.P.K.,Samwoh Corporation Pte Ltd | Fwa T.F.,National University of Singapore | Tan J.Y.,Samwoh Corporation Pte Ltd | And 4 more authors.
Advanced Materials Research | Year: 2013

This paper describes a study that was carried to investigate the use of recycled concrete aggregate (RCA) in aircraft stand rigid pavement at the Singapore Changi Airport. The study aimed to recycle the concrete waste generated from the demolition of the existing aircraft stand rigid pavement to reconstruct the aircraft stand rigid pavement. The study was a continuation of a previous work in which 20% of RCA was used in the rigid pavement. In this study, laboratory tests were carried out to evaluate the use of up to 100% of RCA in rigid pavement. The test properties that were evaluated include compressive strength, flexural strength, drying shrinkage and resistance to chloride ingress. The study showed that it is viable to incorporate high RCA content in concrete. © (2013) Trans Tech Publications, Switzerland.

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