Influence of bonded mortar of recycled concrete aggregates on interfacial characteristics – Porosity assessment based on pore segmentation from backscattered electron image analysis

Kim, Yongjae; Hanif, Asad; Usman, Muhammad; Park, Won-Jun

doi:10.1016/j.conbuildmat.2019.03.265

Cited by 77 publications

(20 citation statements)

References 45 publications

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“…However, at 100%, the compressive strength was 32.2 MPa, which was 3.7 MPa less than that of ordinary concrete. This finding was similar to that of a previous study [24], in which the recycled coarse aggregate had a density of 2.51 g/cm 3 and an absorption rate of 2.85%. Furthermore, the aggregate was slightly stabilized so that the air volume following the replacement was minimal, up to a 60% replacement rate, and increased at 100%.…”

Section: Compressive Strengthsupporting

confidence: 91%

“…However, 60% or more of the replacement produced property changes, and in particular, the air volume increased. This influenced the compressive strength [24,25]. When recycled fine aggregates after modification were used, at replacement rates of 0%, 30%, 60%, and 100%, the compressive strengths in the general strength territory were 25.7, 25.4, 26.5 and 23.8 MPa, respectively, and 36.1, 36.4, 37.3 and 34.8 MPa in the high strength territory, respectively.…”

Section: Compressive Strengthmentioning

confidence: 99%

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A Study on the Properties of Recycled Aggregate Concrete and Its Production Facilities

Kim¹,

Sung²,

Jeon

et al. 2019

Applied Sciences

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In recent years, the amount of construction waste and recycled aggregate has been increasing every year in Korea. However, as the recycled aggregate is poor quality, it is not used for concrete, and the Korean government has strengthened the quality standards for recycled aggregate for concrete. In this study, research was conducted on the mechanical and durability characteristics of concrete using recycled aggregate, after developing equipment to improve the quality of recycled aggregate to increase the use of recycled aggregate for environmental improvements. The results illustrated improvements in the air volume, slump, compressive strength, freezing and thawing resistance, and drying shrinkage. Furthermore, this study is expected to contribute to the increased use of recycled aggregate in the future.

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Section: Compressive Strengthsupporting

confidence: 91%

Section: Compressive Strengthmentioning

confidence: 99%

A Study on the Properties of Recycled Aggregate Concrete and Its Production Facilities

Kim¹,

Sung²,

Jeon

et al. 2019

Applied Sciences

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show abstract

“…As the present study primarily focused on the effect of varying steam-curing conditions, the positive (or negative) effects will be reflected in the hardened concrete (as can be seen from the compressive strength results). It is, however, worth mentioning that the published literature on the fresh state properties of RAC contains disparities owing to the varying w/c ratio, mixing method, and most importantly, the bonded/adhered mortar with the recycled aggregate surface [57,58].…”

Section: Fresh State Concrete Propertiesmentioning

confidence: 99%

Steam-cured recycled aggregate concrete incorporating moderately high early strength cement: effect of binder content and curing conditions

2019

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Steam curing employed for faster strength gain due to higher hydration rate may lead to shrinkage issues, and hence the use of moderately high early strength cement (MESC) is proposed instead of typically used high early strength cement (HESC) which has a high C3S content. This paper evaluates the suitability of MESC for use in precast concrete. The objective was to (i) determine the feasibility of MESC in recycled aggregate concrete (RAC), (ii) determine the optimum steam curing conditions (curing duration, maximum temperature, and duration of holding maximum temperature), and (iii) evaluating the beneficial use of reduced binder content to compensate for steam curing. Four series of RAC were developed which were subjected to nine different steam curing condition, and the resulting strength properties were determined. Though all the developed concrete specimens achieved the design strength of 30 MPa, those cured at 50 °C with 1 h duration of exposure to maximum temperature exhibited the best performance. Further, it was found that even though reducing the binder content reduces the ultimate strength at 28-day age, curing at 70 °C with 2 h exposure to maximum temperature duration (for 7% reduction in binder volume) leads to merely 11.8% strength decline. It is concluded that MESC can be effectively used in steam cured RAC instead of OPC and HESC with meagre strength loss when cured at maximum temperature of 50 °C maintained for 1 h while the total curing time being 4.5 h. Thus, utilizing MESC in RAC shall not only help combat the persistently declining natural resources but also reduced the associated carbon dioxide emissions, thereby promoting sustainable development.

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“…The major reason that affects the quality of RA is the large amount of cement mortar remains on the surface of the aggregate, resulting in higher porosity, water absorption rates and thus a weaker interfacial zone between new cement mortar and aggregates, which weakens the strength and mechanical performance of concrete [21]. The results of a recent study [22] indicated that RA affect the resulting mechanical strength of hardened concrete due to the lower specific gravity and higher water absorption as compared to the natural aggregates (NA). Recycled coarse aggregate (RCA) has about 28% higher bonded mortar content (BMC) with porosity of bonded mortar (BM) almost double as that of recycled fine aggregate (RFA).…”

Section: Technical Analysismentioning

confidence: 99%

Aggregate Recycling in Construction: Analysis of the Gaps between the Chilean and Spanish Realities

et al. 2019

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This study conducts a comparative analysis between Chilean and Spanish reality in regard to the recycling of aggregates and their reuse in road works and urban roads. The current situation of both countries was reviewed through different sources of information such as technical and legal regulation, projects and executed works, to then validate them in Chile by way of interviews to various professionals in the field of urban and interurban road construction, as well as others belonging to government bodies. Spain has extensive experience on this issue, as it has a culture of recycling and reusing aggregates that has produced excellent results, a situation which was taken into account to compare it to Chile's reality. The conclusion is that currently, in Chile, although the existence of recycled aggregate use is known, this is not the case on a technical level for professionals in the sector. It lacks a specific government body that is in charge of this issue and does not have appropriate infrastructure for its treatment. The materials with a promising future within the construction sector are the production of crushed granular bases and the creation of low-resistance concretes, which cannot be used, as laws that regulate them are still being drafted.

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Influence of bonded mortar of recycled concrete aggregates on interfacial characteristics – Porosity assessment based on pore segmentation from backscattered electron image analysis

Cited by 77 publications

References 45 publications

A Study on the Properties of Recycled Aggregate Concrete and Its Production Facilities

A Study on the Properties of Recycled Aggregate Concrete and Its Production Facilities

Steam-cured recycled aggregate concrete incorporating moderately high early strength cement: effect of binder content and curing conditions

Aggregate Recycling in Construction: Analysis of the Gaps between the Chilean and Spanish Realities

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