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Resource utilization of construction and demolition (C&D) waste has great potential to significantly reduce the consumption of natural resources and improve the environment. Meanwhile, establishing a sound policy system and reducing production are the key ways to solve the problem of C&D waste. Numerous studies on C&D waste, …
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The water absorption ratios of concrete with different PET contents at 28 days are shown in Fig. 16. The addition of spherical plastic aggregates and 5% and 10% plastic fine aggregates has little effect on the water absorption of concrete. However, when 15% plastic fine aggregates are added, the water absorption ratio of concrete …
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The water–cement ratio (w/c) has a significant effect on the strength of recycled concrete. In this study, considering the effects of water/cement ratio, strength, and water content of recycled aggregates, two kinds of pulse sequences of low-field nuclear magnetic resonance (LF-NMR) were applied to investigate the water migration …
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One conventional concrete hollow block is estimated to emit 3 to 3.4 kg of CO 2. 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.
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In [12] CO2 absorption for three levels of recycling rates was calculated: 40, 70 and 100. %. The values of 5.4-12.6 % absorbed CO2 in relation to total CO2 emission at a recycling rate of 100 ...
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The programme ValReCon20 has demonstrated the possibility of replacing up to of coarse aggregates with coarse recycled concrete aggregates (CRCA) in concrete of strength class C25/30 ...
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However, the reduction in the MOE will be limited to 10% when RCA with water absorption limited to 2.5% and an oven-dry specific gravity of over 2500 kg/m3 (156 lb/ft3) is used. …
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Density. The density of crushed concrete aggregate is smaller than natural aggregate density. 4. Water Absorption. Water absorption of recycled aggregate is greater than of natural aggregate. It is one of the most significant properties that distinguish recycled aggregate from raw aggregates.
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1. Introduction. Concrete blocks prepared with recycled aggregates have been successfully large-scale manufactured in the construction industry [1].For the gap in mechanical properties with natural aggregate products, researchers proposed many approaches to improve the RACB products, such as strengthening raw materials [2], [3], …
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It consists of a mixture of hardcore (concrete, masonry, bricks, tiles), reinforcement bars, dry walls, wood, plastic, glass, scrap iron and other metals etc. Hardcore makes up about 90% of the total weight of C&D waste, with the unit weight or density of hardcore estimated to be between 2100 to 2300 kg/m3.
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This paper proposed fully recycled aggregate concrete (FRAC), which was prepared by completely replacing natural aggregates (NA) with recycled coarse and fine aggregates (RCA and RFA) and partially replacing cement with recycled powder (RP). ... and concluded that the key limiting characteristics were the high water absorption of …
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The absorption values for coarse recycled aggregate products generally range from 4 to 7% compared with less than 2% for primary aggregates. Higher values up to 8% can be …
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In general, concrete with RCA presented higher absorption than concrete made with NA. ... Interior surface of typical recycled concrete exposed to elevated temperature at 800 • C for 4 h.
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Table 1 represents the typical silica fume's physical characteristics done ... Cakir and Sofyanh examined where they found out that concrete water absorption values significantly decreased, particularly as concrete aged when it contained recycled aggregate and SF. Recycled aggregate concretes incorporating 10% SF have a greater …
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The methods have been used for two different purposes: (a) to measure the interconnected porosity of recycled aggregates, which is useful for concrete mechanical …
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The high porosity and water absorption capacity of recycled aggregates made from normal strength concrete coupled with its low initial water content rendered the aggregate to take up a larger amount of water ... In a typical concrete, some 20–30% of the cement paste lies within 15 µm of aggregate. Therefore, a higher w/c ratio in this …
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This imaginary concrete contains 400 kg of cement, 700 kg of natural sand 0/4 mm (with negligible absorption) and 1000 kg of dry recycled aggregates (>4 mm). …
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CHAPTER 1—INTRODUCTION. Hydraulic cement concrete is a cement and water paste in which aggregate particles are embedded. Aggregate is granular material such as sand, gravel, crushed stone, blast-furnace slag, and lightweight aggregates that usually …
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However, as shown in Chapter 5, there is a greater probability of recycled masonry aggregates (RMAs) showing higher water absorption capacity compared with RCA and thus, for a given replacement level, the former is more likely to produce concrete exhibiting greater permeability and sorptivity than the latter (Soutsos et al., 2011; Gomes and de …
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This work investigated the effects of the crushing index and water absorption of recycled concrete aggregate (RCA) on performance of recycled aggregate pervious concrete (RAPC). It was found that the large RCA water absorption can reduce the cohesiveness between aggregates thereby leading to poor castability of fresh RAPC …
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High water absorption is a typical characteristic of recycled coarse aggregate and is often used to explain the loss of performance of concrete when replacing natural coarse aggregate with recycled coarse aggregate. Extensive attention has been paid to the mean value of the water absorption of recycled coarse aggregate, but not to …
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This imaginary concrete contains 400 kg of cement, 700 kg of natural sand 0/4 mm (with negligible absorption) and 1000 kg of dry recycled aggregates (>4 mm). The water absorption of the recycled aggregates measured at 105 °C is equal to 6.0% as in [50]. 5.2.1. What is expected to happen
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DOI: 10.2139/ssrn.4184139 Corpus ID: 251486395; Capillary Water Absorption Performance and Damage Constitutive Model of Recycled Concrete Under Freeze-Thaw Action @article{Xiao2022CapillaryWA, title={Capillary Water Absorption Performance and Damage Constitutive Model of Recycled Concrete Under Freeze …
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absorption rate and water absorption capacity at 24 h. Keywords Waste management Aggregate Absorption Recycled concrete Workability 1 Introduction Concrete is the most used building material in the construction industry. Its world production is esti-mated to be about 6 billions tons/year [1]. On one hand, this predominant market position
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The limits prescribed for the percentage of water absorption by recycled concrete aggregates varies in different international codes [16], [17]. IS: 383 [1] permits the use of RCA aggregates having water absorption less than of 10% and also suggests that the aggregates are to be pre-wetted to saturation before batching and mixing.
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The reuse of construction and demolition waste as a substitute for natural coarse aggregate in the production of recycled concrete has been widely used. In order to study the capillary water absorption performance of waterborne-polyurethane-modified recycled aggregate concrete (WPUMRC), the effects of different curing systems, …
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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 …
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Our results suggest that water absorption of RCA at 24 h can be seen as the simple sum of the capillary absorption of both the residual cement paste and the initial …
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Assessing the water absorption of concrete has been one of the most common approaches to indirectly evaluating the porosity of concrete and thus its potential …
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2.1. Multi-Recycled Concrete Aggregates. The main difference between natural aggregates (NAs) and recycled aggregates (RAs) is that the second type is made up of both debris of natural aggregates and cement hydration products (cement mortar) [32,38,61].The attached mortar lends RA different characteristics from NA; the main …
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