recycled aggregate higher water absorption

Mitigation of the negative effects of recycled aggregate

Mitigation of the negative effects of recycled aggregate

A pre-saturation time of 5 minutes and the corresponding extra water incorporated in a two staged mixing approach, mitigates the negative effect of recycled aggregate water absorption Jul 15, 2021 Recycled aggregates show, however, high water absorption due to porosity. At saturation, water flows from the inside to the engaging cement

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Theoretical analysis of water absorption kinetics of

Theoretical analysis of water absorption kinetics of

According to BS 8007, aggregates should comply with either BS 882 or BS 1047 and have an absorption, as measured in accordance with BS 812-2, generally not greater than 3%. A paper by Anchor et al discusses the then new BS 8007. Regarding aggregate absorption it says Water absorption of aggregates is retained at 3% maximum. May 19, 2021 Many earlier studies reported that the higher water absorption of fine recycled aggregate and weak interfacial transition zone (ITZ) resulted in the development of the concrete with less strength and durability requirements. This study surmounts the above two factors through pre-saturation and a two-stage mixing approach (TSMA) technique.

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Water absorption limits on aggregates

Water absorption limits on aggregates

Recycled concrete aggregates obtained from CD waste exhibit high water absorption, leading to weakness in the interfacial transition zone between aggregates and cement mixture 18 and a ... One important difference between CRCA and natural aggregates is water absorption. The high water absorption of CRCA is linked to the presence of old mortar (de Juan and Gutierrez, 2009). Dry recycled aggregates behave like sponges in fresh concrete, thus impacting on

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Effect of fine recycled aggregate on the strength and

Effect of fine recycled aggregate on the strength and

Jun 21, 2021 Compared to virgin aggregate, recycled concrete aggregate has tendency of higher water absorption which results in lower workability in fresh concrete and its higher shrinkage, higher creep, lower strength and lower durability, these impediments limits its wider applications in the structural concrete . Fine recycled concrete aggregates (RFAs) contain not only the parent river sand but also a large amount of old cement matrix which exists independently as fine particles (these aggregates having a very high-absorption capacity) or as adhered mortar on the surface of the old river sand particles. The existence of the old adhering cement matrix has resulted in the RFA having smaller density, larger water absorption,

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Water absorption variability of recycled concrete aggregates

Water absorption variability of recycled concrete aggregates

Oct 01, 2014 In this paper, the effects of high temperature exposure of recycled aggregate concretes in terms of residual strengths, capillary water absorption capacity and pore size distribution are discussed. Two mineral admixtures, fly ash (FA) and ground granulated blast furnace (GGBS) were used in the experiment to partially replace ordinary Portland cement for concrete production. Sep 02, 2020 At present, the research results show that the mechanical properties of recycled concrete are weaker than normal concrete due to the high water absorption and high porosity of the recycled aggregate 13. Defects in the mechanical properties of RA concrete have limited its large-scale application in construction sites.

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Water absorption variability of recycled concrete

Water absorption variability of recycled concrete

Waste concrete was recycled and crushed into fine aggregate to prepare a high ductility cementitious composite (HDCC) in this study, for helping dispose the massive amount of construction waste and for reserving natural resources. Firstly, the features of recycled fine aggregate (RFA) were analyzed Mar 20, 2020 Although additional water is used in RAC to satisfy the aggregate water absorption, aiding to achieve the workability slightly higher than that of the NAC, air content of RAC is still higher than that of the NAC. This behaviour can be ascribed to some unsaturated fractured zones within RCA, that are not linked to the permeable pores of aggregate.

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Quality improvement of recycled concrete aggregate by

Quality improvement of recycled concrete aggregate by

The test results show that the water absorption of recycled aggregate mixed with aggregate intensified by RPC grout is lower than that of recycled aggregate, the crush index decreases significantly. 3 57 cement paste in their structure, drying at high temperatures can affect its microstructure 58 and thus modify its water absorption. 59 60 Nevertheless, several studies on the absorption of recycled aggregates use a drying 61 protocol based on the above standard with a temperature of 105C 3,1315. Some 62 studies recommend a reduction of the drying temperature to 70-75C 3,4,16 to ...

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Recycled Concrete Aggregate an overview ScienceDirect

Recycled Concrete Aggregate an overview ScienceDirect

because of its high water absorption rate 4. Investigations were carried out on 11 RA samples obtained from 10 demolition sites and a recycling plant. The study revealed that in most samples, the water absorption of 10 mm aggregates was higher than 20 mm aggregates. It was inferred that smaller size aggregates had more cement Jul 22, 2014 The higher water absorption nature of RCA results from the higher absorption of cement mortar attached to aggregate particles 81. Cui et al., 2015 81 further found that RCA with a higher water ...

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Residue strength water absorption and pore size

Residue strength water absorption and pore size

May 07, 2020 Abstract. In order to study the capillary water absorption characteristics of recycled concrete (RAC) with different replacement rates of recycled coarse aggregate (0, 20%, 40%, and 60%) in freeze-thaw environment, the standard test method of measuring the water absorption of hydraulic cement concrete (ASTM C1585-13) was adopted, and the influence mechanism of freeze-thaw cycle abr asion value for recycled aggregate was obtained as 47.4% and that for natural aggregate as 29.6%. Water absorption of recycled aggregate (4.2%) was found to be higher when compared to the natural aggregate (0.4%). It was found that compressive strength of concrete made from the recycled aggregate is about 76% of the strength of concrete

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Impact Properties of Recycled Aggregate Concrete with

Impact Properties of Recycled Aggregate Concrete with

Recycled aggregate normally has higher water absorption and lower specific gravity 6. The density of recycled aggregate used is lower than the density of normal aggregate. Porosity of recycled aggregates is also much higher than those of natural aggregates 7. Mar 20, 2018 In this test, the water absorption of recycled aggregate is significantly higher compared to that of the natural aggregate with the same particle size. This is resulted from that the old attached mortar in recycled aggregate had a higher water absorption capacity than that of crushed limestone 22, 23. As shown in Table 1, with an increase ...

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Experimental Study of Utilizing Recycled Fine Aggregate

Experimental Study of Utilizing Recycled Fine Aggregate

Mar 29, 2013 It is found that while RCA usually reduces concrete compressive strength due to higher water absorption of the aggregate and the weak residual mortar layer. It is possible to produce concrete that is stronger than a conventional concrete if the source concrete is stronger than that at which the RCA concrete is intended to perform ... Higher porosity of RCA leads to a higher absorption. Mix Design It is generally accepted that when natural sand is used, up to 30 percent of natural crushed coarse aggregate can be replaced with coarse recycled aggregate without significantly affecting any of the mechanical properties of the concrete.

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Mechanical and durability performance of recycled

Mechanical and durability performance of recycled

May 14, 2015 This paper discusses the suitability of producing concrete with 100 % recycled aggregate to meet durability and strength requirements for different applications. Aggregate strength, gradation, absorption, specific gravity, shape and texture are some of the physical and mechanical characteristics that contribute to the strength and durability of concrete. Mar 17, 2016 The quality control of aggregates for concrete involves determining their water absorption and apparent density, indicators of the materials porosity. The standard methods were developed for natural aggregates and are less appropriate for construction and demolition waste recycled aggregates (RAs), which have greater porosity and variability. This paper presents a rapid

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PDF Impact Properties of Recycled Aggregate Concrete

PDF Impact Properties of Recycled Aggregate Concrete

Sep 19, 2020 recycled concrete aggregates and that with normal aggregates is the higher water absorption in the rst one 4,6. This is attributable to the absorption by the mortar that adhered to the original aggregates. This layer of adhered mortar could a ect the deformation properties of concrete made with RCA such as sti ness, shrinkage, and creep. Aug 08, 2019 Summary Fresh concrete made with recycled aggregate tends to be very harsh due to the angular shape and rough surface of the aggregate, require higher water contents due to higher absorption capacity of the cement paste, higher air content due to greater porosity of the recycled aggregates themselves and to the entrained air in the original ...

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Water absorption of recycled aggregates

Water absorption of recycled aggregates

Dec 01, 2020 the mechanical properties of recycled aggregate concrete (RAC) 36 (2) the higher porosity and water absorption of RCA than the companion NA. The water absorbability of RCA, which ranges up to 15% 2, is necessary to know due to the mixture Recycled Aggregate Higher Water Absorption. The recycled coarse aggregate will invariably have lower specific gravity and higher absorption than the original aggregate, due to the presence of cement paste in the recycled aggregate.The compressive strengths of recycled aggregate concrete are lower than those of the same mix designs made with virgin aggregate.

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Water Absorption Study in Recycled Aggregates for

Water Absorption Study in Recycled Aggregates for

Apr 04, 2015 In this paper, three recycled coarse aggregates (RCAs) with different 24-h water absorptions (5.67, 3.12, and 1.98 wt%) were used to produce recycled coarse aggregate concretes (RCACs). Different water absorption rates were obtained by modifying the surface of RCAs with low and high concentration of alkaline organosilicone modifier that is ... Jul 30, 2021 adhered on the recycled aggregate surface, which leads to high water absorption and poor durability of the recycled concrete. Moreover, a more complex ITZ between the fresh mortar and the recycled aggregate was generated in the recycled concrete, as shown in Figure113. Figure 1.

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Experimental Study on the Influence of Water Absorption of

Experimental Study on the Influence of Water Absorption of

The reasons for such restrictions arise from earlier research, that classified fine recycled aggregates (FRA) has being highly heterogeneous, having high water absorption rates and levels of contaminants, that lead to unacceptable performance losses 23. However, recent researches seem to contradict that FRA cannot be used in concrete production. containing 100% washed recycled aggregate was slightly lower (7%) than concrete prepared with natural aggregates. Water absorption, carbonation, and rapid chloride penetration test were also conducted to assess the durability of concrete. Concrete was found permeable for chloride ions.

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