Study Strength of Recycled Concrete Mix Design

2013 ◽  
Vol 423-426 ◽  
pp. 1072-1075
Author(s):  
Xin Hua Zhang ◽  
Sai Tian ◽  
Huai Ru Dai ◽  
Wei Lin ◽  
Zhi Chun Yao ◽  
...  
Keyword(s):  
Concrete Strength ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Mix Design ◽  
Replacement Rate ◽  
Ordinary Concrete ◽  
Concrete Mix Design ◽  
Waste Production ◽  
Concrete Mix

This paper discusses waste production of recycled aggregate concrete is used as the recycled concrete, experiment with different recycled aggregate instead of natural aggregate, the ratio of recycled concrete workability and compressive strength etc performance compared with ordinary concrete, analyzing the change of the recycled aggregate replacement rate on the influence of concrete strength.

Structural Concrete with Recycled Aggregate: Advances in Mechanical Properties, Durability and Sustainability

2016 ◽  
Vol 847 ◽  
pp. 553-558 ◽  
Author(s):  
Marc Antonio Liotta ◽  
Marco Viviani ◽  
Carlotta Rodriquez
Keyword(s):  
Cement Mortar ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Mix Design ◽  
Elastic Behavior ◽  
Structural Concrete ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Ordinary Concrete

A large number of tests has been carried out in the last 15 years all around the world to study the possibility to use recycled concrete aggregates (RCA) to produce structural concrete.Earlier tests indicated that RCA concrete had lower properties in comparison to ordinary concrete, such as lower elastic modulus, a more brittle post-elastic behavior, lower workability, higher shrinkage and creep.Most of these issues have been addressed to the content of cement mortar remaining in adhesion to the aggregate after the recycling processes and that cannot be totally eliminated without high economic and ecological costs. This cement mortar which has undergone the crushing process creates zones of weakness in the RCA, causes higher water absorption, higher concrete porosity and causes the decay of the aforementioned properties.More recent tests prove that Recycled Concrete shows this peculiar problems only with a percentage of substitution of standard aggregates with RCA higher than 30%. Under this percentage recycled aggregate concrete (RAC) can be considered as a standard concrete, on condition that an appropriate mix design is performed.

Effects of Old Aggregate on Concrete Strength

2014 ◽  
Vol 1008-1009 ◽  
pp. 1352-1356
Author(s):  
Hui Lv ◽  
Chun Tao Wang
Keyword(s):  
Coarse Aggregate ◽  
Concrete Strength ◽  
Strain Curve ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Stress Strain ◽  
Ordinary Concrete ◽  
Recycled Coarse Aggregate ◽  
Basic Properties

The basic characteristics of recycled coarse aggregate are completely tested. Crushed the waste concrete through artificial crushing, configured recycled concrete by reference to the mix proportion of ordinary concrete . Through experiments, recycled concrete and ordinary concrete basic properties were tested, the performance of recycled concrete with different coarse aggregate were compared, calculated the strength and amount of mold of recycled concrete; results showed that the basic properties of recycled coarse aggregate and natural aggregate existed certain differences. compared to the pebble-based recycled aggregate concrete strength can reach ordinary concrete strength, and when the new coarse aggregate and recycled coarse aggregate were the half, the strength of concrete was not high, the stress - strain curve and the ordinary concrete stress - strain curves were similar, destructive phenomenons of test cubes were close with ordinary concrete .

Mechanical Research on Bond-Slip Behaviors of Recycled Aggregate Concrete-Filled Square Steel Tubes

2012 ◽  
Vol 166-169 ◽  
pp. 3233-3236 ◽  
Author(s):  
Jun Tao Li ◽  
Jin Jun Xu ◽  
Zong Ping Chen ◽  
Yi Li ◽  
Ying Liang
Keyword(s):  
Bond Strength ◽  
Concrete Strength ◽  
Steel Tube ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Replacement Rate ◽  
Steel Tubes ◽  
Aggregate Concrete ◽  
Bond Slip ◽  
Ultimate Bond Strength

In order to research the interface bond-slip behaviors of recycled aggregate concrete-filled square steel tube (RACFSST), ten specimens using waste concrete were designed for launch test. The three changing parameters were concrete strength grade, embedded length and recycled coarse aggregate replacement rate. The load–slip curves of square steel tubes and recycled aggregate concrete were obtained, and starting bond strength and ultimate bond strength influenced by each changing parameter were analyzed. The results show that the replacement rate had a slight influence on the starting bond strength and ultimate bond strength, while the embedded length had the opposite effect. The shorter embedded length specimens had larger bond strength. The concrete strength had a relatively large influence on them.

Effect of some Key Factors on the Strength of Recycled Concrete

2012 ◽  
Vol 503-504 ◽  
pp. 576-581
Author(s):  
Xue Bing Zhang ◽  
Zhi Fang
Keyword(s):  
Coarse Aggregate ◽  
Cement Mortar ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Key Factors ◽  
Ordinary Concrete ◽  
Concrete Mix ◽  
Rate Maximum ◽  
Cement Strength ◽  
Granule Diameter

Because there exists a used cement mortar layer outside the recycled aggregate, there are more interfaces inside recycled concrete, which would result in recycled concrete has different properties from ordinary concrete. In this paper, the effect of such key factors for recycled concrete mix ratio as water-cement ratio, cement strength, sand rate, maximum granule diameter and gradation on the properties of concrete with recycled coarse aggregate was studied by experiment, and the some useful suggestion for mix ratio of recycled concrete was provided.

Experimental Study on Mechanical Properties of Recycled Concrete Specimens of Marine Engineering

2011 ◽  
Vol 71-78 ◽  
pp. 331-337
Author(s):  
Wen Bai Liu ◽  
Xia Li
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Engineering Application ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Replacement Rate ◽  
Replacement Ratio ◽  
Ordinary Concrete ◽  
Seawater Corrosion ◽  
Marine Engineering

Mechanical properties of recycled concrete under different conditions were studied in this paper. Based on three kinds of replacement percentage of recycled aggregate and four kinds of seawater corrosion conditions, the experimental study of mechanical properties of recycled concrete specimens corroded by seawater and produced under vacuum conditions were conducted, and compared with that of ordinary concrete specimens. Testing results show that compressive strength of recycled concrete decreases with the increase of both the replacement rate of recycled aggregate and the corrosion time by seawater, with the maximum reduce value is 17.96% and 24.52%; Vacuum conditions effectively improve the strength of recycled concrete, improved value is 1.03-1.19 times of the same replacement ratio of recycled aggregate, and 1.00-1.16 times of the ordinary concrete. It provides the reference for marine engineering application of recycled concrete.

scholarly journals Compressive Strength Study on the Freeze-thaw Resistance of Recycled Aggregate Concrete Members

2017 ◽  
Vol 11 (1) ◽  
pp. 270-280 ◽  
Author(s):  
Haicheng Niu ◽  
Yonggui Wang ◽  
Xianggang Zhang ◽  
Xiaojing Yin
Keyword(s):  
Compressive Strength ◽  
Mass Loss ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Fine Aggregate ◽  
Replacement Rate ◽  
Aggregate Concrete ◽  
Freeze Thaw ◽  
Surface Scaling

Introduction: Freeze-thaw resistance of recycled aggregate concrete with partial or total replacement of recycled aggregate compared with that of natural aggregate concrete was investigated in this paper. Method: Ninety specimens were fabricated to study the influence of different recycled aggregate replacement ratios on the surface scaling, mass loss, and residual compressive strength after 100 freeze-thaw cycles. Results: The experiment results indicate that the type of recycled aggregate and its replacement ratio have significant effects on the freeze-thaw performance. The cubic compressive strength of recycled aggregate concrete is overall slightly lower than that of normal concrete. After 100 freeze-thaw cycles, the compressive strength decreases and the reduction extent increases with increasing replacement rate of recycled aggregate. The surface scaling of reinforced recycled concrete prisms tends to be more severe with the increase of freeze-thaw cycles. Conclusion: Furthermore, a notable rise in mass loss and the bearing capacity loss is also found as the substitution ratio increases. Under the same replacement rate, recycled fine aggregate causes more negative effects on the freeze-thaw resistance than recycled coarse aggregate.

scholarly journals Improved Serviceability and Environmental Performance of One-Way Slabs through the Use of Layered Natural and Recycled Aggregate Concrete

2020 ◽  
Vol 12 (24) ◽  
pp. 10278
Author(s):  
Nikola Tošić ◽  
Snežana Marinković ◽  
Yahya Kurama
Keyword(s):  
Environmental Performance ◽  
Concrete Strength ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Aggregate Concrete ◽  
Reinforced Concrete Slabs ◽  
Service Load ◽  
Better Than

Recycled aggregate concrete (RAC), i.e., concrete produced with recycled concrete aggregate (RCA) has been heavily investigated recently, and the structural design of RAC is entering into design codes. Nonetheless, the service load deflection behavior of RAC remains a challenge due to its larger shrinkage and creep, and lower modulus of elasticity. A novel solution to this challenge is the use of layered concrete, i.e., casting of horizontal layers of different concretes. To investigate the potential benefits and limits of layered concrete, this study contains a numerical parametric assessment of the time-dependent sustained service load deflections and environmental impacts of homogeneous and layered NAC and RAC one-way slabs. Four types of reinforced concrete slabs were considered: homogeneous slabs with 0%, 50% and 100% of coarse RCA (NAC, RAC50 and RAC100, respectively) and layered L-RAC100 slabs with the bottom and top halves consisting of RAC100 and NAC, respectively. In the deflection study, different statical systems, concrete strength classes and relative humidity conditions were investigated. The results showed that the layered L-RAC100 slabs performed as well as, or even better than, the NAC slabs due to the differential shrinkage between the layers. In terms of environmental performance, evaluated using a “cradle-to-gate” Life Cycle Assessment approach, the L-RAC100 slabs also performed as well as, or slightly better than, the NAC slabs. Therefore, layered NAC and RAC slabs can be a potentially advantageous solution from both structural and environmental perspectives.

Experimental Study on Bond-Slip between Steel Bar and Recycled Aggregate Concrete

2011 ◽  
Vol 250-253 ◽  
pp. 1651-1656 ◽  
Author(s):  
Qing Feng Huang ◽  
Da Fu Wang
Keyword(s):  
Concrete Strength ◽  
Concrete Cover ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Bond Slip ◽  
Pull Out ◽  
Steel Bar ◽  
Cover Thickness

By a static and repeated pull-out experiment between steel bar and recycled aggregate concrete, and bond-slip curves between recycled concrete with different recycled coarse aggregate(RCA) replacement percentages were recorded. Based on the analysis of the experimental results, replacement percentages of recycled concrete, cover thickness, anchorage length, concrete strength and loading method was investigated. At last, the bond-slip constitutive relation was also discussed.

Microscopic Mechanism Study on Carbonation Resistance of Recycled Aggregate Concrete

2011 ◽  
Vol 194-196 ◽  
pp. 1001-1006 ◽  
Author(s):  
Hai Feng Yang ◽  
Zhi Heng Deng ◽  
Xue Liang Li
Keyword(s):  
Fly Ash ◽  
Coarse Aggregate ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Replacement Rate ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
Concrete Carbonation ◽  
Carbonation Resistance

24 100mm × 100mm × 300mm recycled concrete prisms and 96 150mm × 150mm × 150mm cubes are completed in this paper.The relationships of the carbonation depth in each carbonation age with replacement rate of recycled coarse aggregate and fly ash is studied; The SEM is used to observe the interface structure of recycled coarse aggregate concrete and compared with ordinary concrete, and finally,a recycled concrete carbonation model is proposed. The results showed that: the substitution of recycled coarse aggregate and fly ash cut down the recycled concrete carbonation resistance significantly, which are related with the replacement rate; the content of Ca(OH)2 in the recycled aggregate concrete decreased ,also there are obvious interface transition zone between the recycled coarse aggregate and the new cement;obvious cracks and large voids are exist before the recycled aggregate concrete is loaded, which lead directly to lower carbonation resistance of the recycled concrete.

Microstructural Features of Recycled Aggregate Concrete: From Non-Structural to High-Performance Concrete

2019 ◽  
Vol 25 (3) ◽  
pp. 601-616 ◽  
Author(s):  
Diogo Pedro ◽  
Mafalda Guedes ◽  
Jorge de Brito ◽  
Luís Evangelista
Keyword(s):  
High Performance ◽  
Mechanical Performance ◽  
High Performance Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Sequential Approach

AbstractThe use of concrete-recycled aggregates to produce high-performance concrete is limited by insufficient correlation between resulting microstructure and its influence on mechanical performance reproducibility. This work addresses this issue in a sequential approach: concrete microstructure was systematically analyzed and characterized by scanning electron microscopy and results were correlated with concrete compressive strength and water absorption ability. The influence of replacing natural aggregates (NA) with recycled concrete aggregates (RCA), with different source concrete strength levels, of silica fume (SF) addition and of mixing procedure was tested. The results show that the developed microstructure depends on the concrete composition and is conditioned by the distinct nature of NA, recycled aggregates from high-strength source concrete, and recycled aggregates from low-strength source concrete. SF was only effective at concrete densification when a two-stage mixing approach was used. The highest achieved strength in concrete with 100% incorporation of RCA was 97.3 MPa, comparable to that of conventional high-strength concrete with NA. This shows that incorporation of significant amounts of RCA replacing NA in concrete is not only a realistic approach to current environmental goals, but also a viable route for the production of high-performance concrete.

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