Structural Materials. A Study on a Technology for Producing High Quality Recycled Coarse Aggregate.

Yonezawa, Takeshi; Kamiyama, Yukio; Yanagibashi, Kunio; Kojima, Masaro; Arakawa, Kazuaki; Yamada, Masaru

doi:10.2472/jsms.50.835

Cited by 27 publications

(12 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These observations are consistent with microscopic examination of the new mortar-RA interface, which confirmed that the interfacial zone is less dense than that of natural aggregate, and the old interface between the adhered mortar and the old aggregate acts as a weak link inside RAC rather than the new interfaces when RA was produced from aged lowstrength concrete (Poon et al, 2004;Etxeberria et al, 2006). In efforts to improve the quality of RA, new technology that enables removal of surfaceattached old mortar from the RA has been developed (Yonezawa et al, 2001;Kiyoshi et al, 2007). However, the benefits of high-quality RA in improving the properties of RAC have not been fully explored to date.…”

Section: Introductionsupporting

confidence: 84%

Experimental study on the shear strength of recycled aggregate concrete beams

Choi¹,

Yi²,

Cho³

et al. 2010

Magazine of Concrete Research

112

View full text Add to dashboard Cite

In concrete beam design, the shear capacity of the concrete beam is of great interest because shear failure is associated with an abrupt failure mode that undermines the flexural performance of the beam. Recently, because of the increasing cost of natural resources and environmental concerns, the use of recycled aggregate (RA) in construction is becoming the standard practice. However, the effects of recycled aggregates on the shear strength of concrete have not been fully examined. In this study the effects of RA on concrete shear strength are studied experimentally by performing flexural tests on 20 RA concrete beams with various combinations of span-to-depth ratios (a/d ¼ 1 . 50, 2 . 50, 3 . 25), longitudinal reinforcement ratios (s ¼ 0 . 53%, 0 . 83%, 1 . 61%) and RA replacement ratios (0%, 30%, 50%, 100%). The test results indicate that the concrete shear strength diminishes by up to 30% at 100% replacement ratio compared with the natural aggregate concrete. The shear strengths of the RA concrete beams are also compared with those obtained from the existing models for natural aggregate concrete and some design considerations in using the recycled aggregate concrete are discussed. NotationA b section area of beam (m 2 ) A s steel rebars area (mm 2 ) a/d shear span-to-depth ratio b w , h, d width, depth and effective depth of beam (mm) E c elastic modulus (GPa) E s modulus of elasticity of rebars (GPa) f ck specified concrete compressive strength (MPa) f su specified tension strength of rebar (MPa) f y specified yield strength of rebar (MPa) P c early transverse tension crack load (kN) P cr initial critical shear crack load (kN) P cu ultimate shear load (kN) V cr shearing strength in early shear crack (kN) V u ultimate shearing strength (kN) r principal rebar ratio r/r b relative rebar ratio

show abstract

Section: Introductionsupporting

confidence: 84%

Experimental study on the shear strength of recycled aggregate concrete beams

Choi¹,

Yi²,

Cho³

et al. 2010

Magazine of Concrete Research

112

View full text Add to dashboard Cite

show abstract

“…method, RCA lumps are passed between an outer cylinder and an inner cylinder that rotates eccentrically at a high speed. The adhered mortar can be removed from RCA by this action (Yonezawa et al 2001). In the mechanical grinding method (ball-milling), a drum is divided into small sections.…”

Section: Mechanical Treatment Techniquementioning

confidence: 99%

Quality Improvement Techniques for Recycled Concrete Aggregate: A review

Shaban

Yang

et al. 2019

ACT

134

View full text Add to dashboard Cite

The main problem in using recycled concrete aggregate (RCA) as a construction material is due to the weak adhered mortar which usually has higher porosity and water absorption. It also has lower strength compared to natural aggregate (NA), and it often forms weak interfacial transition zones in the recycled aggregate concrete (RAC). These weak zones lead to negative effects on the mechanical properties and durability performance of RAC. In order to utilize RCA in more effectively as aggregate in concrete, it is necessary to improve the quality and enhance the properties of the attached weak mortar. This paper reviews different treatment methods of RCA based on the published research, and systematically analyses the strengths and weaknesses as well as the applicability and limitations of each method. The advantages and disadvantages of each treatment method, in terms of their technical feasibility, efficiency, economic and environmental impacts, are also discussed, in view of facilitating the selection of the most suitable treatment method for RCA. Although most techniques have been examined and trialed under laboratory conditions, further investigations are required to determine the most effective approach for treating RCA, with consideration not only given to the laboratory scale, but also on a commercial production scale.

show abstract

“…Since demand for concrete as a sub-base is expected to decrease, it is necessary to realize the recycling of aggregate resources by improving the technology for recycling aggregates from demolished concrete. Although efforts are currently made to practically apply concrete incorporating aggregates recycled by advanced treatment (Kuroda et al 2004 andYonezawa et al 2001 At present, 26 billion tons of material is used annually in the world, including approximately 20 billion tons of aggregates for construction, 1 billion tons for steel production, 3 billion tons from forests, and 700 million tons for the production of gold (Brown 2002). In Japan, the amount of resources used for the construction industry is approximately 1.1 billion tons, which represents almost half of the total amount for all industries, 2.4 billion tons.…”

Section: Demolition and Recyclingmentioning

confidence: 99%

Environmental Design for Concrete Structures

Sakai

2005

ACT

View full text Add to dashboard Cite

Concrete is the most important material employed in public works and building construction projects. The large amount of concrete production causes large energy consumption, resources depletion, CO2 emissions, and other environmental impacts. This paper describes the environmental aspects of concrete and proposes environmental design as a new design paradigm for concrete structures. It also describes design examples to illustrate the rationality of environmental design.

show abstract

Structural Materials. A Study on a Technology for Producing High Quality Recycled Coarse Aggregate.

Cited by 27 publications

References 0 publications

Experimental study on the shear strength of recycled aggregate concrete beams

Experimental study on the shear strength of recycled aggregate concrete beams

Quality Improvement Techniques for Recycled Concrete Aggregate: A review

Environmental Design for Concrete Structures

Contact Info

Product

Resources

About