Pore characterization of manufactured aggregates: recycled concrete aggregates and lightweight aggregates

Deshpande, Yogini; Hiller, Jacob E.

doi:10.1617/s11527-011-9749-2

Cited by 30 publications

(18 citation statements)

References 17 publications

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“…50) Tiny enclosed micropores and mesopores, which are harmless, dominated the pore structure of C-CRCA in recycled aggregate concrete. 51) These pores helped prevent ice formation and relieve ice pressure, consequently decreasing the extent of freezethaw damage in the mortar.…”

Section: Failure Mechanismmentioning

confidence: 99%

Assessment of the freeze–thaw resistance of concrete incorporating carbonated coarse recycled concrete aggregates

Wang

et al. 2017

J. Ceram. Soc. Japan

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This study aims to characterise the freezethaw resistance of concrete incorporating carbonated coarse recycled concrete aggregate (C-CRCA) at partial or full replacement rates of coarse natural aggregate (CNA). Experimental work is conducted for C-CRCA with varying CO 2 curing time (0 day, 3 day, 7 day) and C-CRCA weight replacement percentages (0, 20, 50, 100%) for concrete production. Weight loss, relative dynamic modulus of elasticity (RDME) and residual compressive strength were monitored after 300 freezethaw cycles. Pore size distribution and crack volume variation were also measured via nuclear magnetic resonance to investigate changes in the microstructure of the concrete interior. The compressive strength of concrete decreases with the replacement percentage of CNA by the C-CRCA. The internal freezethaw resistance of concrete with C-CRCA was higher or equal to those of concrete with CRCA and CNA. The total replacement of CNA by C-CRCA led to the highest RDME, and 50% replacement of CNA by C-CRCA led to the highest residual compressive strengths after the freezethaw cycles. However, the weight loss was more severe with the increasing replacement of CNA by C-CRCA. Increasing CO 2 curing time improved the frost resistance of C-CRCA concrete. The analyses of concrete mesostructure based on pore size distribution and crack volume variation agreed with the results of RDME and the compressive strength of concrete.

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Section: Failure Mechanismmentioning

confidence: 99%

Assessment of the freeze–thaw resistance of concrete incorporating carbonated coarse recycled concrete aggregates

Wang

et al. 2017

J. Ceram. Soc. Japan

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“…This phenomenon is caused by the density of RC being smaller than in the case of RCA. Decrease of moisture content seems to prove that a larger amount water filled inner pores, than it was in the case of open pores, due to the influence of greater capillary forces [11].…”

Section: Methodsmentioning

confidence: 92%

The Geotechnical Properties of Recycled Concrete Aggregate With Addition of Rubber Chips During Cyclic Loading

Sas¹

2017

geomate

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ABSTRACT:The following paper presents the results of tests performed on the reclaimed waste, namely the Recycled Concrete Aggregate (RCA). Geotechnical study was undertaken, in order to obtain physical and mechanical properties of RCA improved with rubber grains. Such a mix could exhibit increased elastic strain development during load cycles, which are typical for traffic. For better understanding of its exceptional behaviour under repeated loading, cyclic CBR tests were conducted in various stages of loading. For the purpose of bearing capacity analysis, uniaxial test was also conducted. While the cyclic loading and mechanical stabilization are a cause of aggregates crushing, another particle size distribution could occur and may not fulfil quality requirements. Determination of resilient modulus Mr on the basis of a repeated loading test and development of displacements during the tests have also been presented. The M r value for pure RCA was equal to 495.6MPa. The addition of rubber chips in amount 0.5% and 1% results in rise of resilient modulus value, equal to 632.4MPa and 698.0MPa respectively. During the tests the plastic strain abate was recognised. The plastic displacement analysis shows increase of the permanent settlement due to cyclic loading in case of 0% and 1% rubber chips content. The 0.5% rubber chips addition results in smaller plastic displacement. The plastic and elastic displacement was later analysed in order to characterize the deformation behaviour of RCA. The paper proposes also a possible guideline for using the RCA mix as a material in pavement subbase construction.

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“…This is possible because natural aggregates are characterized by the presence of rounded grains, composed mainly of quartz origin with a low roughness. RCA aggregates are rougher and have an irregular shape, which has a significant impact on the water flow and the surface area [25].…”

Section: Literature Reviewmentioning

confidence: 99%

Estimation of Recycled Concrete Aggregate’s Water Permeability Coefficient as Earth Construction Material with the Application of an Analytical Method

2019

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Creating models based on empirical data and their statistical measurements have been used for a long time in the economic sciences. Increasingly, these methods are used in the technical sciences, such as construction and geotechnical engineering. This allows for reducing the costs of geotechnical research at the design stage. This article presents the research carried out on Recycled Concrete Aggregate (RCA) material with is reclaimed crushed concrete rubble. Permeability tests were carried out using the constant head method. Tests were conducted on blends of RCA with the following particle size ranges: 0.02–16 mm, 0.05–16 mm, 0.1–16 mm, and 0.2–16 mm. The gradients used during the tests were between 0.2 to 0.83, which corresponds to gradients encountered in earth construction and are below the critical gradient. Directly from the tests, the flux velocity for the range of tested gradients were calculated based on filtered water volume measurements. The values of the permeability coefficient (k) were then recalculated. Finally, statistical methods were used to determine which physical parameters of the tested material affect the permeability coefficient. The physical parameters selected from the statistical analysis were used to create a model describing the phenomenon. The model can be used to determine the permeability coefficient for a mixed RCA material. The article ends with conclusions and proposals concerning the use of models and the limits of their applicability.

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Pore characterization of manufactured aggregates: recycled concrete aggregates and lightweight aggregates

Cited by 30 publications

References 17 publications

Assessment of the freeze–thaw resistance of concrete incorporating carbonated coarse recycled concrete aggregates

Assessment of the freeze–thaw resistance of concrete incorporating carbonated coarse recycled concrete aggregates

The Geotechnical Properties of Recycled Concrete Aggregate With Addition of Rubber Chips During Cyclic Loading

Estimation of Recycled Concrete Aggregate’s Water Permeability Coefficient as Earth Construction Material with the Application of an Analytical Method

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