Influence of moisture states of natural and recycled aggregates on the slump and compressive strength of concrete

Poon, Chi Sun; Shui, Zhong He; Lam, L.; Fok, Hung-Kit; Kou, Shi Cong

doi:10.1016/s0008-8846(03)00186-8

Cited by 726 publications

(306 citation statements)

References 5 publications

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“…It was shown that presoaking aggregates prior to running the ASR tests produced less early expansion (Scott and Gress, 2004). Also, the high absorption capacity can result in a significant reduction in workability when using RCA (Poon, Shui et al, 2004). Therefore, it was decided that the RCA should be soaked in the mixing water, with an adjustment to account for the absorption capacity of the aggregates.…”

Section: Mortar Bar Mixing Proceduresmentioning

confidence: 99%

Durability Assessment of Recycled Concrete Aggregates for Use in New Concrete Phase II

Ideker¹

2014

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Type of Report and Period Covered14. Sponsoring Agency Code 15. Supplementary Notes 16. Abstract: This Phase II investigation into the durability of new concrete incorporating recycled concrete aggregates (RCA) focused on several goals: 1) Provide corroboration of results obtained in Phase I for a multi-laboratory study related to assessing alkali-silica reactivity (ASR) of RCA in accelerated laboratory tests; 2) Investigate the efficacy of mitigation methods to control ASR in concrete containing potentially reactive RCA; 3) Establish long-term data through placement of concrete blocks containing RCA in an outdoor exposure site in Laramie, WY; and 4) Survey state DOTs and other transportation agencies about their perceptions and usage of RCA ASR in concrete within their agency and how that may be improved through the use of a database tracking tool. From Phase II the following main conclusions were drawn: 1) The coefficient of variation limits in ASTM C 1260-07 do not apply to concrete mortar bars incorporating RCA. It is recommended that further testing, using different RCA and more laboratories (at least six), should be completed before a new standard for RCA and/or incorporation of RCA into the current ASTM C 1260 test may be allowed. 2) Generally, as the replacement level of RCA was reduced, the amount of SCM needed to control deleterious ASR also decreased for the RCA sources investigated in this study. 3) Ternary blends containing metakaolin resulted in the most significant decrease in expansions compared to the mixtures with no SCMs.The results of the transportation agency survey showed the following: 1) A vast majority of agencies believed that sustainability was important to their agency and that it was addressed in a clear and meaningful way. 2) A majority, 54%, of agencies believed they had specific guidance for the use of RCA in new concrete; however, only 15% believed that there was strong information from the federal level about the use of RCA in new construction. 3) Of all respondents, 77% indicated their agency was concerned about alkali-silica reaction in concrete in general for their agency. 4) The biggest barriers to using RCA were noted as concerns about quality, a lack of standards and specifications, and unclear guidance on the testing of RCA. 5) The biggest concerns specific to a source of RCA when considering it for use in new construction were increased shrinkage concerns, ASR and residual chlorides. 6) The most sought-after information about a potential RCA source when considering it for use were the existing condition of the RCA when it was taken out of service, the reason it was taken out of service, whether repairs were performed to the structural element taken out of service, and the age of the RCA. 17.

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Section: Mortar Bar Mixing Proceduresmentioning

confidence: 99%

Durability Assessment of Recycled Concrete Aggregates for Use in New Concrete Phase II

Ideker¹

2014

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“…Durability, porosity, and mechanical properties of concrete made with recycled aggregate were affected by the percentage of recycled aggregate used. Results [11][12][13][14][15][16] indicated that 50% recycled aggregates content was the optimum amount that can be used in a concrete mix for structural applications to meet specific mix requirements. In addition, physical properties of recycled aggregates must be evaluated to adjust the mixture proportioning to achieve the required behavior.…”

Section: Many Research Efforts Have Demonstrated An Inversementioning

confidence: 99%

Utilization of Recycled Coarse Aggregate in Concrete Mixes

Abdelfatah¹,

Tabsh²,

Yehia³

2012

JCEA

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In this paper, the effect of the source of recycled coarse aggregate on the properties of concrete is investigated. The tests were conducted on concrete made from three sources of recycled aggregates: (1) old concrete with unknown strength, (2) old concrete with a known compressive strength of 21 MPa, and (3) old concrete with a known strength of 42 MPa. The three sources of recycled aggregates were used to produce new concrete with a target compressive strength of 21 MPa. The first and third sources of recycled aggregates were used in producing concrete with target strength of 42 MPa. A control mix was designed with aggregates from natural sources. The research included two methods of making recycled concrete. One concrete mix was produced using the recycled aggregate and adding more water than the control mix, to reach the target slump, while the second concrete mix was produced using the same amount of water as the control mix but with additional superplasticizer to maintain the target slump. The results obtained in this research showed that the concrete compressive strength depends on the source of recycled aggregates; the stronger the source of recycled aggregate, the higher the compressive strength of the produced concrete. Furthermore, the compressive strength of the first concrete mix was about 10%-20% lower than the compressive strength of the control mix. However, when superplasticizers were used, the compressive strength was around the same value as the control mix.

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“…En los resultados obtenidos experimentalmente se comprobó, tal y como se puede ver en la figura 3, que el hormigón fabricado con 25% de árido reciclado y sin adición, obtuvo la misma resistencia que el HP tal y como determinaron otros investigadores (Etxeberria, 2004;Poon, Shui, Lam, Fok & Kou, 2004;Grupo de Trabajo, 2006). Los hormigones con 100% de árido reciclado sufrieron una reducción del 12% respecto al HP a 28 días de curado.…”

Section: Resistencia a Compresiónunclassified

Propiedades del hormigón de árido reciclado fabricado con adiciones, activa e inerte

Pavón

Etxeberria²,

Martínez

2011

Revista de la Construcción

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Influence of moisture states of natural and recycled aggregates on the slump and compressive strength of concrete

Cited by 726 publications

References 5 publications

Durability Assessment of Recycled Concrete Aggregates for Use in New Concrete Phase II

Durability Assessment of Recycled Concrete Aggregates for Use in New Concrete Phase II

Utilization of Recycled Coarse Aggregate in Concrete Mixes

Propiedades del hormigón de árido reciclado fabricado con adiciones, activa e inerte

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