19.2.1 Recycled concrete aggregate (RCA) Coarse RCA complies to the requirements of maximum 5% masonry content, 5% fine materials, 0.5% lightweight material, 5% asphalt, 1% foreign material and 1% acid soluble sulfate, and is suitable for use in concrete as per BS 8500-2 (2006). In designated concrete RC20/25 to RC40/50, RCA can automatically ...
This study provides a comprehensive review on recycled aggregate (RA) and recycled aggregate concrete (RAC) regarding their history, recycling, reuse and …
Recycled Coarse Aggregate (RCA) The RA was sourced from a wrecked residential structure in Chennai's West Mambalam. The aggregate obtained had a specific gravity value of 2.78 and was crushed to the necessary particle size of 10–20 mm. RA is created by crushing and sorting construction waste, such as concrete, brick, and asphalt, …
2.1.3 Recycled coarse aggregates. RACs selected in the study were gathered from three sources. One source was the 1-year-old laboratory waste concrete (collected from tested full-scale RC beams) with a w/c value of 0.45 and with a 150 mm 3 cubic compressive strength f cu150 of 37.5 MPa (called as RCA1). The other two …
In the Ghanaian construction industry, coarse aggregates are obtained solely from natural rock deposits to produce concrete. This practice puts undue pressure on natural rock …
This paper examined the potential of recycled aggregate use in Ghana and concluded that concrete rubbles from demolished concrete structures and Air Cooled Blast Furnace Slag (ACBFS), a waste...
But for SCC with recycled coarse aggregate (RCA), a significant increase in T 500 time of about 38.89% and 116.67% was observed at 10% and 20% RP respectively. This can be attributed to trade-offs between full replacement of FA by RP, leading to a higher interlocking between the particles in a fresh state and the …
concrete properties. This review focuses on structur al RC made with coarse r ecycled aggrega te from concrete waste. The main. objective is to pro vide a state of the art report on RC' s ...
A total of 36 concrete mixtures were considered with natural aggregate and three W/C ratio (i.e. .4, .5 and .6) as well as two replacement levels of RCA (i.e. 75, ) and three replacement levels of RFA (i.e. 30, 60, ). The mechanical performance, in terms of cube compressive strength, splitting tensile strength and axial compressive ...
The carbon emission per unit hollow block could be 2.5 to 2.7 kgCo 2 if 50% of the cement was replaced with coal ash and 90% of the natural aggregate was replaced with recycled coarse aggregate. 5. Recycled aggregates combined with coal ash can be used to create grade A hollow masonry units with sufficient characteristic strength, …
1. Introduction. Managing the waste generated by human activity is a worldwide challenge. According to Eurostat [1], in 2016 around 2535 Mt of waste was generated in the EU as a whole, 36.44% of which (~92.4 Mt) attributable to the construction industry. The enormous impact of such vast amounts of waste has driven the institution …
Recycled coarse aggregates. The RCA used in this research came from the site of a building demolition project. With sizes of 300–600 mm, the RCA (excluding steel reinforcement) was recrushed by a jaw crusher to control the size range from 5 to 30 mm. Screens were used to divide the crushed RCA into components with 5–10 mm, 10–20 …
An artificial aggregate, the plam kernel shell obtained from palm nut, can be classified as organic lightweight aggregate.Tests on the concrete made with this material as coarse aggregate, show a ...
(For example, RAC-100: recycled coarse aggregate concrete with a 100 % replacement ratio.) 2.3.4. SEM test. The micromorphology of the old mortar and the new mortar was analyzed by SEM. The equipment used was a Quanta 600 FEG with a resolution of 1 nm and magnification of 100 to 400,000 times. SEM samples were …
1.Size of Coarse Aggregates: The size of the coarse aggregate depends on the use of the concrete is to be poured. For large-scale concreting operations without complex reinforcement, large aggregates of size 80 mm, 40 mm, 20 mm are used. For the simple construction of residential or other buildings, 20 mm is the maximum size will be used.
Using repeatedly recycled coarse aggregate (RCA) to prepare structural concrete is an important means for addressing the economic, environmental, and social problems caused by the shortage of natural aggregate resources. In this study, the durability of three generations of repeatedly recycled aggregate concrete (RAC) …
The strength and durability properties of the recycled aggregate concrete (RAC) have been affected by the cracks and the weak interfacial transition zone (ITZ) of the recycled coarse aggregates (RCA). However, the mechanical and physical features of RCA can be improved by microbially induced calcite precipitation (MICP).
The recycled concrete families were created by replacing parts of the natural aggregates forming families of concrete with 0%, 20%, 50%, and of aggregates from recycled sources.
The average flexural strength shown in Fig. 11 increased by increasing the percentages of replacement of coarse aggregates by recycled concrete aggregates after aging of seven and twenty-eight days. At the age of seven days the flexural strength increased from to 102.31%, 107.51%, 108.03% and 104.57% for 25%, 50%, 75% …
The optimum percentage of replacement of natural coarse aggregate with treated recycled coarse aggregate is also found out based on compressive strength. It suggests that treatment using fly ash ...
The mineral compositions of brick powder and concrete powder were shown in Fig. 3.The main mineral compositions of brick powder were quartz (SiO 2), feldspar and hematite; The main mineral phases in concrete powder were calcite (CaCO 3), SiO 2, hydration product Ca(OH) 2 and incompletely reacted C 2 S. The characteristic …
Recycled waste glasses were used as coarse. and fine aggregates replacement in concrete. Coarse. aggregates were replaced with Green Bottles coarse aggregates. at th ird, h alf, two thirds, and ...
In contrast, the natural coarse aggregates were replaced by recycled coarse aggregate using five different replacement percentages, i.e. 0 (R0), 30% (R30), 50% (R50), 70% (R70) and (R100 ...
Recycled coarse aggregate. The RAs utilized in this research came from the site of highway demolition project in Jiangsu Province, China. These RAs with sizes of 9.5–31.5 mm contained a large number of fines. The morphology of the aggregate samples was performed under Sirion field emission electron microscope (FEI, America). The …
To this end, a synthesis of experimental studies with different recycled coarse aggregate (RCA) substitute rates (0%, 30%, 50%, 70% and ), different prismatic sizes of 70 × 70 × 210, 100 × 100 × 300, 150 × 150 × 450 and 200 × 200 × 600 mm are carried out to investigate the size effect of RAC with consideration of the …
Du et al. [6] reported that the micro-hardness of recycled coarse aggregate (RCA) was much higher than that of the interfacial transition zones (ITZs) in the RAC, and the micro-hardness of the interface between the RCA and the new mortar matrix was the lowest. Poon et al. [7] investigated the effect of microstructure of ITZ on the compressive …
The cement used is ordinary Portland cement (P·O 42.5) produced by a local cement plant. The density of cement is 3.15 g/cm 3, the initial setting time and final setting time are 142 min and 198 min, respectively, and the compressive strength of 3d and 28d are 28.2 MPa and 48.7 MPa respectively.The sand used is the washed medium sand of the …
The adherence of mortar on the surface of RCA affects the mechanical and durability properties of the recycled aggregate concrete (RAC) (Abdulla 2014, Dhir and Paine 2007, Xu and Shi 2000, Ho et al. 2013, Otsuki et al. 2003, Katz 2004, Revathi et al. 2014, Saravanakumar and Dhinakaran 2014, Juan De and Gutiérrez 2009).Puthussery et …
The incorporation of recycled aggregates in concrete not only reduces the extraction of natural resources, but also decreases landfill disposal of construction and demolition waste. ... and applies this methodology in a real context pertaining the procurement of coarse aggregates to ready-mix concrete plants. A case study of two …
The use of recycled coarse aggregates in concrete is subject to rigorous physical and mechanical analyses, presented in Table 2, ensuring their suitability, which include evaluating factors like bulk density, specific gravity, water absorption, abrasion loss, crushing value, and impact value.These parameters provide valuable insights into the …
Recycled Coarse Aggregate (RCA) concrete construction technique can be called as 'green concrete', as it minimizes the environmental hazard of the concrete waste disposal. Indian standard recommends target mean compressive strength of the conventional concrete in terms of water cement ratio (w/c). The present work is an …
In pursuit of those aims, the present study explored the effect of replacing 25%, 50%, 75% or of coarse natural with recycled aggregate and simultaneously …