Carbonation resistance of recycled aggregate concrete

Leemann, Andreas; Loser, Roman

doi:10.1016/j.conbuildmat.2019.01.162

Cited by 60 publications

(35 citation statements)

References 34 publications

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“…Similar results were obtained by Thomas et al (Thomas et al, 2013). Most of the research work carried out up to date define that concrete produced employing RCA achieved lower carbonation resistance due to its high porosity of RCA Leemann and Loser 2019), however the carbonated or un-carbonated state of RCA could modify this behaviour. After 28 days of CO2 exposure, the concretes produced with 50% of RCA and 50% of FA suffered a greater carbonation process.…”

Section: Carbonation and Chloride Resistancesupporting

confidence: 82%

Influence of High Volume Fly Ash and Recycled Aggregates in Chloride and Carbonation Resistance of Concrete

Etxeberria¹,

Álvarez²

2020

XV International Conference on Durability of Building Materials and Components. eBook of Proceedings

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This paper deals with the evaluation of the influence of recycled concrete aggregate (RCA) and the employment of high volume of fly ash (FA) on the physical, mechanical and durability (chloride ion penetration and carbonation) properties of concretes. The obtained values of which, being compared to those of conventional concretes. Concrete was produced using 0%, 25% and 50% FA in replacement of Portland cement, and 0% and 50% of RCA in substitution of natural aggregates. All the concretes were produced employing an effective water-cement ratio of 0.50. The physical properties at 28 days and the compressive strength at 7, 28 and 90 days were determined in all the concretes produced as well as the assessment of durability (penetration of chlorides and depth of carbonation) on all concrete mixtures. The depth of the carbonation was determined after submitting every concrete sample to a series of accelerated tests at 20% of CO2 concentration during 7, 14 and 28 days after the curing period in the humidity room and precondition in the laboratory. The chloride penetration was determined at 28 and 90 days of curing. It was concluded that the employment of 50% of un-carbonated RCA increased the early strength of concrete produced using FA, and at late ages, RCA concretes achieved similar strength when 25% of FA was employed. The concrete produced with 50% of FA achieved the highest resistance to chloride ion penetration also when RCA was employed. Although the use of FA increased the carbonation depth of the concrete samples, the employment of the un-carbonated RCA reduced that effect. The employment of RCA with CEM II or binder with 25% of FA caused the lowest carbonation depth.

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Section: Carbonation and Chloride Resistancesupporting

confidence: 82%

Influence of High Volume Fly Ash and Recycled Aggregates in Chloride and Carbonation Resistance of Concrete

Etxeberria¹,

Álvarez²

2020

XV International Conference on Durability of Building Materials and Components. eBook of Proceedings

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“…It was also found that CO 2 diffusion is faster in RCA-concrete than in NCA-concrete, leading to a weak resistance to aggressive environment in industrial areas. This finding is supported by the work of Leemann and Loser [23] who concluded that the RCA-concrete carbonation resistance is decreased either by the porous nature of the RCA grains or is already carbonated before being used to make new concrete. The authors stated that the carbonation resistance was not affected by using dry or pre-saturated RCA.…”

Section: Introductionsupporting

confidence: 55%

Recycled Concrete Aggregates and Their Influences on Performances of Low and Normal Strength Concretes

2020

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Recycled materials are now widely used in various industrial sectors to enhance sustainability and reduce environmental charges. Using recycled aggregates in concrete production significantly lowers demand for natural aggregates and the amount of solid waste sent to landfills. This paper summarizes the main results of a study undertaken to design low and normal strength concrete with various replacement ratios of coarse recycled concrete aggregates (RCA). To persuade the concrete industry to use recycled materials as one of the main components of concrete produced, the overall mechanical and durability performances of the RCA-concrete should be close or even similar to the concrete made with natural ingredients. The present research adopted an approach that consists of designing a series of low and normal strength with RCA having an equal target 28-day design strength to the corresponding natural aggregates concrete but while varying the water–cement ratios (w/c). Coarse recycled concrete aggregates, obtained by crushing waste concrete debris collected from different construction and demolition waste sources, were used in three different proportions of 30%, 50% and 100% (by weight) to produce new concrete with various w/c ratios and different compressive strength grades. Concrete mixes produced with general use Portland cement and various RCA contents were investigated in terms of their key mechanical and durability performances. The mechanical properties (crushing value) of the used RCA were visibly lower than the natural coarse aggregates (NCA). Thus, RCA-concrete showed lower performance than the NCA-concrete. It was found that by using up to 30% coarse RCA, the mechanical properties of concrete were not significantly affected. Beyond 30% of partial replacement of NCA by the coarse RCA, a continuing decrease in the mechanical performance with an increase in RCA amount was found. However, reducing the w/c ratio of concrete designed with the coarse RCA resulted in a compressive strength improvement, a better resistance to sulphate attack, carbonation, and chloride ion penetrations. Additionally, a proper design of Portland cement concrete produced with various proportions of RCA could also contribute to promoting sustainability in the construction industry and lowering its environmental impact.

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“…6 The environmental impact of concrete production can be decreased by the use of cement with reduced clinker content or the reuse of concrete waste provided by the demolition of buildings in recycled aggregate concrete (RC). 7 It is well known that the packing of particles in concrete has great effects on the 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%

Retracted: Sensitivity analyzing of compressive strength of concrete aggregates by adaptive neuro fuzzy approach

Jović¹,

Marković

Djurovic³

et al. 2019

Structural Concrete

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The main aim of the study was to analyze the impact of cement content, slump and for different percentage of recycled coarse aggregates (RCA) on the compressive strength prediction of the concrete. The analyzing is performed for different days of modeling of the concrete aggregates. Adaptive neuro-fuzzy inference system (ANFIS) was used in order to determine the parameters influence on the compressive strength prediction. Variable selection process was used to select the most dominant factors, which affect the compressive strength prediction of the concrete aggregates. Results indicated that the cement content has the strongest impact on the compressive strength. Furthermore, combination of cement content and RCA is the optimal combination which has the highest impact on the compressive strength.

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Carbonation resistance of recycled aggregate concrete

Cited by 60 publications

References 34 publications

Influence of High Volume Fly Ash and Recycled Aggregates in Chloride and Carbonation Resistance of Concrete

Influence of High Volume Fly Ash and Recycled Aggregates in Chloride and Carbonation Resistance of Concrete

Recycled Concrete Aggregates and Their Influences on Performances of Low and Normal Strength Concretes

Retracted: Sensitivity analyzing of compressive strength of concrete aggregates by adaptive neuro fuzzy approach

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