The water absorption of recycled concrete aggregate is higher than natural aggregate which results in an increase in water cement ratio to get required workability of concrete. The resistance of recycled aggregate to mechanical actions i.e., impact and crushing is lower than natural aggregate, but the values are in acceptable limits.
that the properties such as density, water absorption, specific gravity, and crushing value have a negative influence on recy-cled aggregate concrete quality. Grabiec et al.9 concluded that the method of bio-deposition of calcium carbonate improved the quality of recycled aggregate. It led to reduc-tion in the water absorption of RCA.
Nov 27, 2012· High water absorption and lower specific gravity for 13 mm recycled concrete aggregate are due to increased amount of weak attached mortar compared to that for 20 mm recycled concrete aggregate. Fine aggregate was deliberately omitted in the mixes to create large open textured porous concrete.
properties are well-known factors of recycled aggregate concrete(RAC): a lower density, elastic modulus, strength and a higher water absorption capacity. Due to the fact that recycled aggregate has a proportional mortar which attached to aggregate, it gives a higher porosity and a lower strength to RAC than the normal concrete.
Recycled concrete aggregates contain not only the original aggregates, but also hydrated cement paste. This paste reduces the specific gravity and increases the porosity compared to similar aggregates. Higher porosity of RCA leads to a higher absorption. Mix Design
Aug 26, 2014· It can be noticed in Table 2 that recycled aggregates have a significant higher water absorption capacity and a lower density than natural ones. In spite of the high water absorption capacity of the used RCA, it remains within the range recommended by the design standards (McNeil and Kang 2013; Kang et al. 2014).
In this paper, the permeability properties of fine recycled aggregate concrete are presented. The FRA used come from demolished concrete of known properties. Mixes with 10%, 30%, 50% and by volume replacement of fine natural aggregates (FNA) with FRA were produced and tested for water
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 ...
Recycled roof tile aggregate has higher water absorption, crushing values and abrasion values than the normal aggregate but exhibits lower specific gravity and bulk density, as shown in Table 2. Aggregates with such characteristic are generally referred to as low-quality aggregates due to the inferiority of such properties to normal concrete ...
relatively higher water absorption. Compressive strength of untreated recycled aggregate concrete can be lower by about 15% compared to original concrete. Properties of Recycled Concrete Aggregates and concrete made with them are enhanced by addition of appropriate nano-materials such as …
Aggregates generally absorb water, both fine aggregate and coarse aggregate. The recycled aggregate is the one which absorbs more amount of water when compared to other naturally available aggregates.
Reduction of slump was 5.3% when recycled ceramic aggregate was used at a replacement level of 25% and its water absorption was 0.55%, which was higher than that of natural aggregate at 0.23% . Compressive strength of concrete made with ceramic insulator and glass concrete was 16% and 26.34% lower as compared to the conventional concrete .
recycled fine aggregate from crushed waste concrete. The basic properties and grading are provided in Table 2 and Table 3. The recycled fine aggregate had much higher water absorption than that of river sand. In order to reduce the effect of grading, the recycled fine aggregate was sieved and recombined to get the same gradation as the river sand.
density and absorption. Moreover, the study analyses how the recycled aggregate (both percentage and quality) and the mixing procedure (pre-soaking or adding extra water) influence the recycled concrete strength of dif-ferent categories (high or low water to cement ratios). When recycled aggregate absorption is low (under 5%),
May 20, 2014· Recycled coarse aggregate (RCA) made from waste concrete is not a suitable structural material as it has high absorption of cement mortar, which adheres on the aggregate surface and on the tiny cracks thereon. Therefore, when using RCA made from waste concrete, much water must be added with the concrete, and slump loss occurs when transporting.
waste concrete as recycled aggregate can yield signiﬁcant environ-mental impact. This encourages urgent steps towards increasing the recycling rate of demolished concrete as aggregate in new con-crete construction. The broad use of recycled aggregate in concrete is hindered by its higher water absorption (two to three times that of normal
This is due to the migration of water absorbed by the aggregate to the paste around particles of aggregates, then, the water absorption will influence volume of water and pores in the paste. Recycled fine aggregate has high water absorption because it contain a large quantity of hydrated cement paste from the demolished concrete.
As the recycled aggregates present have a higher water absorption capacity, a higher content of fine materials, and a rougher surface (larger surface area), the water content of the mixture needs to be modified in order to obtain matrices with the same consistencies of those determined when using natural aggregates 78,79.
However, the use of fine RCA below 2 mm is uncommon in recycled aggregate concrete because of the high water demand of the fine material smaller than 150 μm, which lowers the strength and increases the concrete shrinkage significantly. This high water absorption and high cohesion of fine RCA also makes concrete quality control very difficult.
Found that the water absorption capacity of recycled aggregate reflects aggregate and aggregate is the markedly higher water absorption of the recycled aggregate reflects on the amount of cement paste adhering to the surface of the aggregate particles. 1.2 Studies on Recycled Aggregate Recycled aggregate concrete passing 4.76 mm sieve
Water absorption of recycled aggregate influence both fresh and hardened concrete properties. Recycled sand will be avoided, due to its absorption capacity, which would no doubt produce a shrinkage effect. Workability of recycled aggregate concretes is affected by the absorption capacity of the recycled aggregates.
May 14, 2015· In general, concrete made with RA showed less durability due to high pore volume which led to high permeability and water absorption. High water absorption is due to cement paste adhered on the aggregate surface. However, this can be countered by achieving saturated surface dry (SSD) conditions before mixing.
With this criterion, aggregates with bulk specific density higher than 2160 kg/m3, water absorption lower than 8% and Los Angeles abrasion loss under 40%, are obtained.•The results can also be ...
Use of recycled materials as aggregates in civil engineering applications is beneficial because it reduces the environmental impacts and cost of obtaining concrete. The most significant difference in the physical properties of coarse recycled concrete aggregates RCA reflected in most studies is its higher water absorption capacity as
3.1 Recycled Concrete Aggregates (RCA): Angular with rough surfaces Higher water absorption Lower density Higher abrasion loss May fail sulfate soundness test May contain higher level of sodium chloride 3.2 Concrete Made with RCA: 3.2.1 Fresh Concrete Harsh due to angularity and roughness of RCA Slump loss High water content Higher air content ...
The results revealed that bulk density of control mix containing natural aggregates was higher with minimum water absorption as compared to recycled aggregates concrete. No carbonation has been observed in concrete using natural and recycled coarse aggregates after a period of 28 days of carbon dioxide exposure.
Because recycled aggregate contains mortar from the original concrete, it is more porous and absorptive than many natural aggregates. Recycled aggregate had water absorption of 9.6%. The workability of concrete, as the amount of recycled aggregate was increased, the concrete required more water to maintain adequate
recycled aggregate will absorb more water. Water absorption of recycled aggregate can be proven from the higher percentages of water absorption than the specification. In the context of this research, water absorption was 7.5% and this score was higher than the WSDOT (2009) specification in …
The recycled aggregates are characterized by a high water absorption capacity which can be linked to the presence of the remained unreacted cement attached to the surface of the gravel. (see picture 1). The difference in water absorption capacity has an effect on both the fresh and the hardened state of the concrete mixture.
1. Recycled coarse aggregates have lower specific gravity, higher water absorption, LA abrasion loss, thermal coefficient, and sulfate soundness loss compared with those of aggregates. 2. Recycled fine aggregates have lower specific gravity and higher water absorption than siliceous sand. 3.