scholarly journals Effects of fines content and maximum particle size on mechanical properties and saturated hydraulic conductivity of recycled concrete aggregates for unbound roadbed materials in Vietnam

2021 ◽  
Vol 9 (6) ◽  
pp. 239-244
Author(s):  
Hong Nam Thai ◽  
Akira Kato ◽  
Hoang Giang Nguyen ◽  
Tien Dung Nguyen ◽  
Ton Kien Tong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Hydraulic Conductivity ◽  
Saturated Hydraulic Conductivity ◽  
Recycled Concrete ◽  
Fines Content ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Maximum Particle Size ◽  
Maximum Particle

Influence of Material Properties on Hydraulic Conductivity and Strength of Aggregates Used for Pavement Base

2012 ◽  
Vol 446-449 ◽  
pp. 2641-2645 ◽  
Author(s):  
Fu Ming Liu ◽  
Duan Yi Wang
Keyword(s):  
Hydraulic Conductivity ◽  
Material Properties ◽  
Recycled Concrete ◽  
Fines Content ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Strength Constant ◽  
Pavement Base ◽  
Crushed Limestone

The hydraulic conductivity and strength of several aggregates (limestone, gravel and recycled concrete) are very important for pavement base construction. To study the influence of fines content on hydraulic conductivity and strength, constant/falling head permeability and CBR tests were performed. The results show that hydraulic conductivity exponentially decreases as fines content increases. Their values were also found to vary significantly as a function of aggregate type, gradation, and density. Particle degradation of recycled concrete aggregates is higher than crushed limestone and gravel, which leads to lower hydraulic conductivity values.

Effects of maximum particle size of coarse aggregates and steel fiber contents on the mechanical properties and impact resistance of recycled aggregate concrete

2021 ◽  
pp. 136943322110179
Author(s):  
DongTao Xia ◽  
ShaoJun Xie ◽  
Min Fu ◽  
Feng Zhu
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Steel Fiber ◽  
Impact Resistance ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Coarse Aggregates ◽  
Maximum Particle Size ◽  
Maximum Particle

Fiber reinforced recycled aggregate concrete has become a new type of green concrete material. The maximum particle size of coarse aggregates and steel fiber contents affect the mechanical properties and impact resistance of recycled aggregate concrete. However, such studies are rare in literature. The present paper shortens the gap through experimental study. A total of 144 specimens of 12 kinds of concrete mixtures were tested, which adopted different steel fiber volume admixtures (0%, 0.8%, 1.0%, 1.2%) and recycled coarse aggregates in different maximum particle sizes (9.5, 19, 31.5 mm) replacing 30% natural coarse aggregate. The compressive strength, splitting tensile strength, and impact resistance of the 12 concrete mixtures were tested. The results showed that the compressive strength, splitting tensile strength, and impact resistance of recycled aggregate concrete increased first and then decreased with the increase of the maximum particle size. The recycled aggregate concrete with the maximum particle size of 19 mm had the highest mechanical properties and impact resistance. Besides, with the increase of steel fiber content, the compressive strength, splitting tensile strength, and impact resistance of recycled aggregate concrete showed an increasing trend. Considering a large amount of experimental data and the coupling effect of steel fiber contents and the maximum particle size of coarse aggregates, the Weibull distribution function was introduced to analyze the impact test results and predict the number of resistance to impact under different failure probabilities. The results showed that the number of blows of the recycled aggregate concrete followed a two-parameter Weibull distribution, and the estimated value of the number of resistance to impact for failure increased with the increase of the failure probability.

Influence of Maximum Particle Size, Fines Content, and Dust Ratio on the Behavior of Base and Subbase Coarse Aggregates

2017 ◽  
Vol 2655 (1) ◽  
pp. 20-26 ◽  
Author(s):  
Rabindra Chaulagai ◽  
Abdolreza Osouli ◽  
Sajjad Salam ◽  
Erol Tutumluer ◽  
Sheila Beshears ◽  
...  
Keyword(s):  
Particle Size ◽  
High Strength ◽  
Maximum Size ◽  
Fines Content ◽  
Coarse Aggregates ◽  
Maximum Particle Size ◽  
Maximum Particle ◽  
Improved Performance ◽  
Aggregate Base

Unbound aggregate base and subbase layers are the main load-bearing layers in a pavement structure. Size and shape properties of these aggregate materials should be controlled to ensure proper workability during construction and improved performance for pavement longevity. The effects of gradation, maximum particle size, fines content (percentage passing the No. 200 sieve), and dust ratio on the quality of aggregates were investigated by performing many soaked California bearing ratio tests on a crushed limestone material. The dust ratio represents the amount of fines content divided by the amount of minus No. 40 sieve material. The dust ratios studied were 0.4, 0.6, and 1.0. Two gradations commonly used in Illinois, with maximum particle sizes of 1 in. and 2 in., were studied to analyze the effect of fines content with respect to maximum particle size in the gradation. A typical range of fines contents (i.e., 5%, 8%, and 12%) was also considered. The results show that the gradation, dust ratio, and fines content should be taken into account in the selection of aggregate properties for stability requirements. Aggregates with larger maximum size particles provide high strength, and they are not affected as much as aggregates with smaller maximum size particles by an increase in fines content. The aggregates with smaller maximum size particles provide lower strength. It was also concluded that samples with a dust ratio of 1.0 do not necessarily result in an aggregate material with low strength.

scholarly journals Physical Characterization of Dutch Fine Recycled Concrete Aggregates: A Comparative Study

Proceedings ◽  
2019 ◽  
Vol 34 (1) ◽  
pp. 7 ◽  
Author(s):  
Marija Nedeljković ◽  
Jeanette Visser ◽  
Siska Valcke ◽  
Erik Schlangen
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Water Absorption ◽  
Size Distribution ◽  
Surface Area ◽  
Recycled Concrete ◽  
Natural Sand ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates

In the Netherlands, yearly 20 Mt Construction- and Demolition waste (CDW) is being produced mainly consisting of concrete and masonry rubble. This is two third of the yearly production of concrete (33 Mt). Currently, less than 1 Mt/year of the 20 Mt/year CDW is recycled in new concrete (mainly as coarse recycled concrete aggregates). This preliminary study being part of a larger study, is aiming to increase that amount, amongst others by focusing on use of the fine recycled concrete aggregates. Fine recycled concrete aggregates (fRCA) appear promising for (partial) replacement of natural fine aggregates (sand) and cement in new concrete. Nevertheless, they can be expected to have adverse properties and components that may reduce the performance of the concrete. Their physical, chemical and mechanical properties, which thus may significantly differ from that of natural sand, are still far from being fully investigated. The present paper focusses on characterization of physical properties of fRCA for finding the most critical indicators for fRCA quality. The tests include particle size distribution, morphology, BET surface area, solid density and water absorption of individual and total fractions (0–0.25 mm, 0.25–4 mm and 0–4 mm). The tests are performed on three fRCAs with different origin. Natural river sand with 96 wt.% of SiO2 was also studied to provide a baseline for comparison. Experimental results showed that, on the one side, the particle size distribution, surface area and amounts of individual fractions of fRCAs are significantly different from that of natural sand and that there is a large difference between each other. This is caused by variations of the parent concrete properties and by the type of recycling technique and processes (one step or multiple steps crushing). On the other side, fRCAs have comparative solid densities, which were still lower than that of natural sand. It was also shown that difference in water absorption between fractions 0.25–4 mm and 0–4 mm is very small in all three fRCAs groups. The results of this study will be used for future correlations between investigated properties of fRCAs with properties of concretes with fRCAs. This will be investigated in the next stage of the project, such that these correlations can enable production of durable concretes with fRCAs and assist recyclers in optimization of their production processes based on quality control of fRCAs.

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