Effect of microstructure of ITZ on compressive strength of concrete prepared with recycled aggregates

Poon, Chi Sun; Shui, Zhong He; Lam, L.

doi:10.1016/j.conbuildmat.2004.03.005

Cited by 824 publications

(315 citation statements)

References 9 publications

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“…Thus, the aggregates which have moderate initial moisture content, depending on the condition of storage, absorb a certain amount of free water, and lower the initial W/C in the interfacial transition zone ITZ at early hydration. Newly formed hydrates gradually fill the region and strengthen the interfacial bond between the aggregates and cement [19]. These phenomena could finally generate various shrinkage behaviours.…”

Section: Effect Of Aggregate Quality On the Shrinkagementioning

confidence: 99%

Time-dependent behaviour of high performance concrete: influence of coarse aggregate characteristics

Makani

Vidal

Pons

et al. 2010

EPJ Web of Conferences

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Abstract. This paper examines the influence of coarse aggregate characteristics on the time-dependent deformations of High Performances Concretes (HPC). Four concretes made using the same cement paste but incorporating different types of aggregate (rolled siliceous gravel, crushed granite, crushed limestone and crushed siliceous gravels) were studied in order to investigate the effect of aggregate properties on the compressive strength, modulus of elasticity, shrinkage and creep. The results indicate that the aggregate type has a significant effect on creep and shrinkage deformations of HPC. An influence of the shape of aggregate on time-dependent deformations has also been observed. On the basis of these results, long-term behaviour seems to be correlated to the characteristics of the Interfacial Transition Zone (ITZ) strongly depending on the mineralogical nature and properties of aggregates. The experimental results are compared with the values calculated using the current Eurocode 2 model in order to assess the accuracy of the predictions.

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Section: Effect Of Aggregate Quality On the Shrinkagementioning

confidence: 99%

Time-dependent behaviour of high performance concrete: influence of coarse aggregate characteristics

Makani

Vidal

Pons

et al. 2010

EPJ Web of Conferences

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“…For that reason, recycling CDW as a new aggregate source for concrete has received much more attention due to its feasibility, as well as its environmental and economic benefits [4]. Using recycled concrete aggregate (RCA) for concrete structures in many countries is still controversial and not easy to implement because of the lower qualities of RAC [5] and more complicated microstructure [6] such as containing large flat Ca(OH)2 crystals (CH crystal, about 20-25% of the volume of solids in the hydrated paste) which accumulated in the voids and in the cement paste [7]; a huge amount of pores and cracks; especially when it holds two interfacial transition zone (ITZ) systems including: new ITZ between RCA and new cement paste; old ITZ between old natural aggregate and old adhered mortar [6], which causes negative effects on performance of RAC [8]. Which is why, numerous studies have been conducted to evaluate and improve the mechanical and durability properties of RAC.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of Recycled Aggregate Concrete Properties by a New Treatment Method

Bui

Satomi

Takahashi

2018

GEOMATE

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ABSTRACT:Recently, decreasing natural sources of aggregate accompanied by increasing large quantities of construction and demolition waste (CDW) cause challenges for environment and construction industry. A significant solution for this is to recycle CDW as a new aggregate source for concrete. However, using recycled concrete aggregate (RCA) in concrete involves various obstacles and controversial issues in controlling the quality of recycled aggregate concrete (RAC). This study is an effort to improve the quality of RAC containing 100% coarse RCA by using pozzolanic and sodium silicate solution as new treatment solutions. This study examined performance abilities of RAC after being treated with new treatment solutions and a new mixing procedure. The mechanical properties of RAC were evaluated based on testing of concrete under various conditions. The significant results indicated that sodium silicate combined with pozzolanic materials can improve mechanical properties of RAC containing 100% coarse RCA. At 20% concentration of sodium silicate and silica fume, the compressive strength of RAC could improve up to 36%. Achievements of this approach demonstrated its effectiveness in enhancing the strength of RAC, which is potentially applied to treating RCA for concrete in the future.

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“…7 and 8 that RAC made with RCA obtained approximately the same strength as the corresponding CT concrete. The slightly greater strength of the RA concrete relative to the CT concrete may be attributed to a stronger bond developed at the ITZ between the old mortar and the original aggregate of RAC (which was obtained from the concrete with the compressive strength of approximately 50 MPa) (38)(39)(40); therefore, the strengthcontrolling link of the RA concrete was the ITZ between the new mortar and the RCA, where the interfacial bond was the weakest phase in the concrete. These results are similar to those in previous studies (41,42).…”

Section: Compressive Strengthmentioning

confidence: 99%

Influence of bagasse ash and recycled concrete aggregate on hardened properties of high-strength concrete

et al. 2018

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ABSTRACT:This research aimed to use of bagasse ash as a cement replacement in high-strength recycled aggregate concrete (HS-RAC). Crushed limestone was replaced with 100% recycled concrete aggregate (RCA) and the ground bagasse ash (GBA) was used to partially replace ordinary Portland cement (OPC) at 20, 35 and 50%wt of binder to cast HS-RAC. The results indicated that the replacing of crushed limestone with RCA had a negative impact on the properties of the concrete. Increasing the amount of GBA in HS-RAC resulted in a decrease in density and an increase in the volume of permeable pore space. The concrete mixtures prepared with 20%wt GBA replacement of OPC promoted greater the compressive strength than the conventional concrete (CT concrete) at 90 days or more. HS-RAC with GBA (up to 50%) was more durable in terms of chloride ion penetration resistance, although it had lower compressive strength than the CT concrete. RESUMEN: Influencia de la ceniza de bagazo y los áridos de hormigón reciclado en las propiedades de endurecimiento de hormigones de alta resistencia.En esta investigación se utilizó ceniza de bagazo como sustituto del cemento en hormigón de alta resistencia con áridos reciclados (HS-RAC). La piedra caliza fue sustituida por un árido 100% reciclado de hormigón y la ceniza de bagazo molida (GBA) en diferentes porcentajes (20, 35 y 50% en peso del material cementante) fue utilizada para reemplazar parcialmente al cemento Portland para producir hormigón de tipo HS-RAC. Los resultados indicaron que la sustitución de la piedra caliza molida por áridos de hormigón reciclado tiene un efecto negativo en las propiedades del hormigón. Aumentar la cantidad de GBA en el HS-RAC redujo la densidad e incrementó el volumen del espacio de los poros permeables. Las mezclas de hormigón preparadas reemplazando 20% en peso del cemento Portland por ceniza de bagazo molida presentaron mayor resistencia a la compresión que el hormigón convencional a los 90 días o más. El HS-RAC con GBA (hasta 50%) tuvo una durabilidad mayor que el hormigón convencional en términos de resistencia a la penetración de iones de cloruro, a pesar de tener una menor resistencia a la compresión.PALABRAS CLAVE: Hormigón; Árido; Resistencia a la compresión; Durabilidad; Cloruros ORCID ID: P. Rattanachu

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Effect of microstructure of ITZ on compressive strength of concrete prepared with recycled aggregates

Cited by 824 publications

References 9 publications

Time-dependent behaviour of high performance concrete: influence of coarse aggregate characteristics

Time-dependent behaviour of high performance concrete: influence of coarse aggregate characteristics

Enhancement of Recycled Aggregate Concrete Properties by a New Treatment Method

Influence of bagasse ash and recycled concrete aggregate on hardened properties of high-strength concrete

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