Evaluation of various treatment methods for enhancing the physical and morphological properties of coarse recycled concrete aggregate

Al-Bayati, Hanaa Khaleel Alwan; Das, Prabir Kumar; Tighe, Susan; Baaj, Hassan

doi:10.1016/j.conbuildmat.2016.02.176

Cited by 241 publications

(80 citation statements)

References 35 publications

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“…Furthermore, uncleaned recycled aggregates show an attached mortar content equal of about 30% while the aggregates cleaning led to a decrease of the attached mortar up to about 15%. Heat treatment method [8,9] -The coarse recycled concrete aggregate samples were heated at four different temperatures: 250˚C, 350˚C, 500˚C and 750˚C for a period of one hour in a conventional electric oven. The use of heat treatment method is successful in improving various physical properties including water absorption, specific gravity, porosity and freezing and thawing.…”

Section: Mechanical Grindingmentioning

confidence: 99%

“…Simultaneously, the present calcium metasilicate particles that was used to coat the | CONFERENCE PROCEEDINGS INTERNATIONAL CONFERENCE (2016) | recycled concrete aggregate surface would be dissolved during mixing and are expected to function as a filler with the product of cement hydration for the densification of the interface structure, which improves bond strength at contact between the aggregate surface and the cement matrix. In [9] the coarse recycled concrete aggregate was soaked in an acidic solution composed of hydrochloric acid (HCl) (37%) and acetic acid (C2H4O2) (99.7%) at a low concentration of 0.1mole for 24 h at room temperature around 20˚C. In [13] the aggregates were submerged in HCI (hydrochloric acid) solution at 0.1 molarity for 24 h at 20˚C.…”

Section: Pre-soaking In Acidmentioning

confidence: 99%

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Načini Poboljšanja Recikliranog Agregata – Pregledni Rad

Despotović¹

2016

Zbornik GFS

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Section: Mechanical Grindingmentioning

confidence: 99%

Section: Pre-soaking In Acidmentioning

confidence: 99%

Načini Poboljšanja Recikliranog Agregata – Pregledni Rad

Despotović¹

2016

Zbornik GFS

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“…On the other hands, the hydration products of cement in hardened paste can be dissolved in acid solution Tam et al 2007;Al-Bayati et al 2016). Thus, acidic …”

Section: )mentioning

confidence: 99%

“…There have been numerous studies reporting on surface modifications of RAs using carbonation and acid treatment, focusing on the fact that mortar adhered to the surface of RAs (cement matrix) contains profuse Ca(OH) 2 (Chen et al 2017;Tam et al 2007;Kong et al 2010;Al-Bayati et al 2016;Zhan et al 2014). The surface modification with carbonation is a method that uses accelerated carbonation, which reacts highly concentrated carbon dioxide with Ca(OH) 2 of the adhered mortar on the aggregate surface under dry or wet environments (Zhan et al 2014;Zhang et al 2015).…”

Section: )mentioning

confidence: 99%

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Evaluation on the Surface Modification of Recycled Fine Aggregates in Aqueous H2SiF6 Solution

Ryu¹,

Kim²,

Shin³

et al. 2018

Int J Concr Struct Mater

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Recycled aggregates (RAs) production techniques are essential for the material circulation society because RAs from demolished concrete waste can sustainably be reused as a concrete material. However, RAs can bring about several performance decreases when they are used for recycled aggregate concrete (RAC) because of the low qualities (i.e., high water-absorption rate and low density) caused by the attached hydrated cement paste on the RA surface. Therefore, both the production of high-quality RAs and the surface modification of RAs are significantly important for the extension of RAC utilization. This paper focuses on the surface modification of RFA to reduce the water absorption rate and increase density. Hydrofluorosilicic acid (H 2 SiF 6 ), which is one of the by-products in phosphoric acid manufacture, is used herein for the surface modification of the RFA. The physical properties and mechanical performance of mortar using RFA were evaluated after RFA modification. Consequently, the proposed method is effective in reducing water absorption rate and increasing density of RFA. The density of RFAs was slightly increased by 0.5-2.6% after modification. On the other hand, the water absorption rate decreased by 4-18% after modification. The compressive strengths of mortar at 28 days ages showed 18.1 MPa with modified RFA and 16.2 MPa with RFA.

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The influence of aging on the fracture characteristics of recycled aggregate concrete through three methods

Fallahnejad

Davoodi

Nikbin

2020

Structural Concrete

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In this research, to assess the impact of aging on the fracture properties of recycled aggregate concrete (RAC), three‐point bending tests were carried out on 260 specimens. Then, work of fracture method (WFM), size effect method (SEM), and boundary effect method (BEM) were utilized for analysis of fracture parameters. The result showed that fracture energy values for RAC were 4.2%, 7.1%, 22.7% and 24.2% less than natural aggregate concrete (NAC) ones at 3, 7, 28 and 90 days, respectively. Based on calculation of the characteristic length, the behavior of RAC is more ductile than NAC at early ages. However, through time, the ductility of RAC becomes less than NAC. On average, the ratio of fracture energy achieved from WFM (GF) to initial fracture energy achieved from SEM (Gf) for RAC and NAC was 2.38 and 2.14, respectively. The comparison of fracture energy obtained by BEM and modified WFM showed that these values were close to each other.

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Evaluation of various treatment methods for enhancing the physical and morphological properties of coarse recycled concrete aggregate

Cited by 241 publications

References 35 publications

Načini Poboljšanja Recikliranog Agregata – Pregledni Rad

Načini Poboljšanja Recikliranog Agregata – Pregledni Rad

Evaluation on the Surface Modification of Recycled Fine Aggregates in Aqueous H2SiF6 Solution

The influence of aging on the fracture characteristics of recycled aggregate concrete through three methods

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