Performance analysis of recycled aggregate concrete with chemical admixture

There is an increasing trend towards using recycled aggregate (RA) in concrete due to the shortage of high quality natural aggregates. The use of RA in concrete results in the conservation of natural resources, protects the environment and encourages sustainable construction. Though some studies have been conducted on the use of recycled aggregate concrete (RAC), the effect of mixture composition on its properties has not been well addressed. In the reported study, the effect of mixture composition, namely cement content and water/ cement ratio and the proportion of RA on the mechanical properties of RAC was evaluated, with the intention of developing varying grades of RAC. As reported in earlier studies, the properties of RAC were generally inferior to that of normal aggregate concrete (NAC). Notwithstanding this, RAC with acceptable mechanical properties can be produced utilizing RA, for example RAC with low strength can be used in non-structural applications. The construction industry should be encouraged to use RAC in building construction; as its use will lead to technical, economic and environmental benefits. Further, the use of RAC will lead to a sustainable development of the construction industry, particularly in regions that lack good quality natural aggregates.Based on the data developed in the reported study, the following quantities of RA are recommended to produce RAC: (i) 20% to produce low strength (20--30 MPa) concrete, (ii) 40% to produce medium (30-50 MPa) concrete and high strength (more than 50 MPa) concrete. Mathematical correlations between the mechanical properties of RAC with varying mix design parameters, such as cement content and water cement ratio and the quantity of RA, are also reported. These correlations can be used to predict the properties of RAC prepared with other proportions of RA and mix design parameters.bond strength, compressive strength, mixture proportions, modulus of elasticity, morphology, recycled aggregate concrete, tensile strength Discussion on this paper must be submitted within two months of the print publication. The discussion will then be published in print, along with the authors' closure, if any, approximately nine months after the print publication.

Section: Introductionmentioning

confidence: 99%

Influence of mix composition on the properties of recycled aggregate concrete

Zaben

Maslehuddin

Al‐Amoudi

et al. 2021

“…Many studies were conducted on the behavior of concretes containing RCA (e.g., References 10–17). As was mentioned in literature, mechanical strength and durability characteristics of concretes having RCA were generally inferior in comparison with those without RCA 18,19 . This is attributed to the poor quality of RCAs owing to the porous nature of the attached mortar, resulting in their lower mechanical strength and durability‐related properties 20 .…”

Section: Introductionmentioning

confidence: 88%

Mechanical and durability properties of steel fiber‐reinforced concrete containing coarse recycled concrete aggregate

Kaplan

Bayraktar

Gholampour

et al. 2021

The focus of this study is to investigate the effect of using coarse recycled concrete aggregates (RCAs) as an alternative material to natural coarse aggregate on the fresh, mechanical and durability behavior of concrete reinforced with steel fiber. Eighteen unique concrete mixes with RCA content of 0%, 50%, and 100% and steel fiber content of 0%, 1%, and 2% were prepared, and tests were performed to study slump, density, compressive and splitting tensile strengths, flexural behavior, surface hardness, surface abrasion resistance, water absorption, and sorptivity of each mix. It is shown that concrete containing RCA has a lower unit weight, compressive, splitting tensile and flexural strength, flexural toughness, surface hardness, and abrasion resistance, and a higher water absorption and sorptivity in comparison with conventional concrete. An increased compressive, splitting tensile and flexural strength, flexural toughness, surface hardness, and abrasion resistance, and a decreased water absorption and sorptivity of concrete with an increased steel fiber content from 1% to 2% is less significant compared to those from 0% to 1%. The results also show that, at RCA content of 50%, incorporating 1% steel fiber develops a concrete mix with similar or even better properties compared to unreinforced conventional concrete. At 100% RCA content, incorporating 2% steel fiber develops a concrete mix with similar properties to unreinforced conventional concrete having water to cement ratio of 0.3, but inferior properties to unreinforced conventional concrete having water to cement ratio of 0.5. These findings indicate that recycled aggregate concrete with similar or even better properties compared to concrete with natural aggregate can be developed through properly designing mixes, providing a great avenue toward the production of green construction material for structural applications.

“…The indexes of highperformance concrete are often better than those of ordinary concrete. [36][37][38][39][40][41] Therefore, if the high-performance concrete is used to column, earthquake damage to the column will be greatly reduced. Taking the workshop column and the plaster layer as an example, the detail categories and the corresponding detail seismic damage descriptions are shown in Table 1.…”

Section: The Components and The Detail Seismic Damagementioning

confidence: 99%

“…In general, the column is made of normal concrete rather than high‐performance concrete. The indexes of high‐performance concrete are often better than those of ordinary concrete 36–41 . Therefore, if the high‐performance concrete is used to column, earthquake damage to the column will be greatly reduced.…”

Section: The Determination Of the Components And The Detail Seismic Dmentioning

confidence: 99%

Research on the safety assessment of RC workshop buildings in earthquake site based on the fuzzy comprehensive evaluation

Sun

Zhang

2020

The safety assessment of damaged buildings in earthquake site, which is always performed by experienced experts and is very important during the postearthquake emergency period. However, the conclusions often vary from person to person because of the limited number of experts and the differences in their knowledge, backgrounds, specific research directions, and practical field experience. Therefore, it is necessary to find a fast and accurate calculation model. A single-story reinforced concrete column workshop is taken as an example in this paper. The earthquake damage assessment analysis and component detail earthquake damage are appraised according to the experts' previous earthquake experience and the qualitative provisions in the standard "Post-earthquake Field Works, Part 2: Safety Assessment of Buildings" (GB18208.2-2001). Based on these, the detail seismic damage is quantified. A mathematical model for the safety assessment of the single-story reinforced concrete column workshop is established by quantifying the relevant qualitative provisions in the national standards and applying the two-level fuzzy comprehensive evaluation method. The model is simple to use, which enables the general safety evaluators to share the experts' experience and minimizes the differences among the assessment results of different evaluators. K E Y W O R D S component detail earthquake damage, earthquake site, fuzzy comprehensive evaluation, safety assessment, single-story reinforced concrete column workshop 1 | INTRODUCTION Earthquake is a threat to people and building, 1 which have caused considerable losses and casualties. 2 The seismic performance of buildings will be changed greatly after earthquake. 3-5 After earthquake, rapid and accurate building damage and safety assessment is critical. 6-8 The