Flexural behavior of large scale semi-precast reinforced concrete T-beams made of natural and recycled aggregate concrete

2019 ◽  
Vol 198 ◽  
pp. 109525 ◽  
Author(s):  
Mohamed F.M. Fahmy ◽  
Lamiaa K. Idriss
Keyword(s):  
Reinforced Concrete ◽  
Large Scale ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Flexural Behavior ◽  
Aggregate Concrete

Flexural behavior of reinforced geopolymer concrete beams with recycled coarse aggregates

2021 ◽  
pp. 136943322110262
Author(s):  
Haiyan Zhang ◽  
Keyue Wan ◽  
Bo Wu ◽  
Zhonghao Hu
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Reinforced Concrete Beams ◽  
Recycled Aggregate ◽  
Flexural Behavior ◽  
Replacement Ratio ◽  
Aggregate Concrete ◽  
Bending Capacity

Geopolymer recycled aggregate concrete (GRAC) is a new green construction material, which uses geopolymer as the binder and recycled concrete as aggregates. To compare the flexural performance of GRAC and ordinary recycled aggregate concrete (RAC) beams, static loading tests were conducted on seven GRAC beams and three RAC beams. The effects of the replacement ratio of recycled aggregates (RAs), the replacement patterns, and the reinforcement ratio on the flexural behavior of GRAC beams are evaluated. The test data show that the replacement ratio has no significant effect on the cracking pattern, failure mode, or bending capacity of GRAC beams, but the replacement pattern does have an effect. Under a given replacement ratio, replacing only the larger fraction of natural aggregates (NA) with RA improves the concrete strength and crack resistance of both RAC and GRAC beams, compared to that using same replacement percentage for all fractions. Due to the lower elastic modulus and strength of GRAC prepared in this study, the GRAC beams have lower height of neutral axis and greater deflection than RAC beams at the same load level and possess slightly lower cracking load, bending capacity, and ductility. The bending capacity of GRAC beams can be predicted by the formulas proposed for ordinary reinforced concrete beams in the Chinese code GB50010-2010, ACI 318-11, or BS EN 1992-1-1:2004 codes, but the safety margin is generally lower than that of ordinary reinforced concrete beams.

scholarly journals Seismic Behavior of Concrete-Filled Circular Steel Tubular Column–Reinforced Concrete Beam Frames with Recycled Aggregate Concrete

2020 ◽  
Vol 10 (7) ◽  
pp. 2609 ◽  
Author(s):  
Zongping Chen ◽  
Ji Zhou ◽  
Zhibin Li ◽  
Xinyue Wang ◽  
Xingyu Zhou
Keyword(s):  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Seismic Behavior ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Scale Model ◽  
Hysteresis Curve ◽  
Small Scale ◽  
Skeleton Curve ◽  
Aggregate Concrete

The application of recycled aggregate concrete (RAC) in concrete filled steel tubular (CFST) structures can eliminate the deterioration of concrete performance caused by the original defects of the recycled aggregate, which also provides an effective way for the recycling of waste concrete. In this paper, a test of a small scale model of a circular CFST column-reinforced concrete (RC) beam frame with RACs under low cyclic loading was presented in order to investigate its seismic behavior. The failure modes, plastic hinges sequence, hysteresis curve, skeleton curve, energy dissipation capacity, ductility and stiffness degeneration of the frame were presented and analyzed in detail. The test results show that the design method of the recycled aggregate concrete filled circular steel tube (RACFCST) frame complies with the seismic design requirements of a stronger joint followed by the stronger column and the weaker beam. The hysteresis curve of the frame is symmetrical, showing a relatively full shuttle shape; at the same time, the ductility coefficient of the frame is greater than 2.5, showing good deformation performance. In addition, when the frame is damaged, the displacement angle is greater than 1/38, and the equivalent damping ratios coefficient is 0.243, which indicates that the frame has excellent anti-collapse and energy dissipation abilities. In summary, the RACFCST frame has good seismic behavior, which can be applied to high-rise buildings in high-intensity seismic fortification areas.

scholarly journals Experimental Study of Compressive Properties and Environmental Impact of Recycled Aggregate

2021 ◽  
Vol 8 ◽  
Author(s):  
Ma Xuetong ◽  
Gao Debin
Keyword(s):  
Environmental Impact ◽  
Moisture Content ◽  
Large Scale ◽  
Environmental Risks ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Fiber Reinforced ◽  
Compressive Properties ◽  
Aggregate Concrete

As the main component of fiber-reinforced recycled aggregate concrete, the properties of recycled aggregate determine whether recycled aggregate concrete can be used in engineering applications. To study the compressive properties and environmental impact of recycled aggregate, large-scale indoor compression tests were carried out on recycled aggregate under different moisture contents, concrete aggregate ratios, dry-wet cycles, and loads. The results showed that the crushing rate and settlement first increased and then decreased upon increasing the moisture content. Upon increasing the concrete aggregate ratio, the settlement continuously decreased, and the crushing rate decreased from 157.2 to 82.5%. Upon increasing the number of dry-wet cycles, the settlement continued to increase to an upper limit of about 17.5%, and the crushing rate increased to 35%. Upon increasing the load, the settlement and crushing rate of the aggregate increased. These results show that the effects of aggregate ratio, moisture content, and dry-wet cycles on settlement were caused by crushing the aggregate. Based on this, a formula was constructed to predict the final settlement of reclaimed aggregate. The leaching amount of Cr in recycled aggregate was 0.0175–0.0375 mg/L under normal conditions, but under extreme conditions, the leaching amount of some sampling points was greater than in the standard requirements. This means that recycled aggregate may pose environmental risks that should be mitigated during use. Recycled aggregate can be used to construct sponge city storage and reuse facilities, as well as fiber-reinforced recycled aggregate concrete, but its sources need to be determined to ensure that it does not pose environmental risks.

scholarly journals Call for papers on special issue “Performance-based Service Life Design of reinforced recycled aggregate concrete”

2020 ◽  
Vol 2 (1) ◽  
pp. 045-045
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Chloride Ion ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Special Issue ◽  
Aggregate Concrete ◽  
Service Life Design ◽  
Life Design

Aim & Scope: Sustainability requires a judicious use of natural resources. Reducing the consumption of natural aggregates and ensuring adequate durability of reinforced concrete infrastructures are major steps towards sustainability. Performance-based Service Life Design and recycled aggregate concrete are intense research fields. Considering the research maturity of each subject on its own, it is time to couple them and deliver knowledge on performance-based Service Life Design for reinforced concrete structures incorporating recycled aggregates. This Special Issue of Materials International constitutes a way to disseminate results and findings from original studies, experimental programs, empirical, analytical and numerical modelling of initiation period (carbonation- and chloride ion-related), propagation period or both (service life). Probabilistic, semi-probabilistic and deterministic approaches are welcome.

Recycled aggregate concrete from large-scale production to sustainable field application

2020 ◽  
Vol 262 ◽  
pp. 119979 ◽  
Author(s):  
Humera Ahmed ◽  
Mohammed Tiznobaik ◽  
Sumaiya B. Huda ◽  
M. Shahidul Islam ◽  
M. Shahria Alam
Keyword(s):  
Large Scale ◽  
Field Application ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Scale Production ◽  
Aggregate Concrete ◽  
Large Scale Production

scholarly journals Flexural Strength of Internally Stiffened Tubular Steel Beam Filled with Recycled Concrete Materials

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6334
Author(s):  
Ahmed W. Al Zand ◽  
Mustafa M. Ali ◽  
Riyadh Al-Ameri ◽  
Wan Hamidon W. Badaruzzaman ◽  
Wadhah M. Tawfeeq ◽  
...  
Keyword(s):  
Flexural Strength ◽  
Large Scale ◽  
Steel Tube ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Flexural Behavior ◽  
Concrete Material ◽  
Strength Capacity ◽  
Concrete Materials

The flexural strength of Slender steel tube sections is known to achieve significant improvements upon being filled with concrete material; however, this section is more likely to fail due to buckling under compression stresses. This study investigates the flexural behavior of a Slender steel tube beam that was produced by connecting two pieces of C-sections and was filled with recycled-aggregate concrete materials (CFST beam). The C-section’s lips behaved as internal stiffeners for the CFST beam’s cross-section. A static flexural test was conducted on five large scale specimens, including one specimen that was tested without concrete material (hollow specimen). The ABAQUS software was also employed for the simulation and non-linear analysis of an additional 20 CFST models in order to further investigate the effects of varied parameters that were not tested experimentally. The numerical model was able to adequately verify the flexural behavior and failure mode of the corresponding tested specimen, with an overestimation of the flexural strength capacity of about 3.1%. Generally, the study confirmed the validity of using the tubular C-sections in the CFST beam concept, and their lips (internal stiffeners) led to significant improvements in the flexural strength, stiffness, and energy absorption index. Moreover, a new analytical method was developed to specifically predict the bending (flexural) strength capacity of the internally stiffened CFST beams with steel stiffeners, which was well-aligned with the results derived from the current investigation and with those obtained by others.

STUDY ON FLEXURAL BEHAVIOR OF RECYCLED AGGREGATE CONCRETE BEAMS USING GLASS FIBERS

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
V. Bhikshma ◽  
K. Pradeep Kumar
Keyword(s):  
Glass Fiber ◽  
Glass Fibers ◽  
Fiber Content ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Flexural Behavior ◽  
Alternative Source ◽  
Aggregate Concrete ◽  
Potential Alternative ◽  
The Moment

In this work, an attempt is made to investigate the influence of the glass fiber on the natural and recycled aggregate concrete. Ten beams of size 1500 mm x150 mm x 230 mm were cast and curing was done for 28 days. The flexural behavior of beams is studied in the present work with glass fiber for recycled aggregate concrete. There was total of five batches of concrete mixes for the grade M30 for natural and recycled aggregate. The glass fibers were added in proportion by 0.50%, 1%, 1.5% and 2% by weight of cement. The load carrying capacity of specimens with 100% (RCA) with 2% fiber content is increased by 14% compared to that of 100% (RCA) with 0.5% fiber content. Compared to beam A (NCA) 0%fibre, the moment of beam E (RCA) at 2%fibre is decreased by 6%. The investigations indicated encouraging results for Recycled Aggregate Concrete (RAC) beams with glass fibers in all aspects, thus, pointing to recycled aggregate as potential alternative source of aggregate.

scholarly journals Analytical Model to Predict Residual Flexural Capacity of Recycled Aggregate Concrete Beams with Corroded Longitudinal Rebars

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Zhenghao Zou ◽  
Guojiao Yang ◽  
Tian Su
Keyword(s):  
Experimental Data ◽  
Theoretical Analysis ◽  
Strain Distribution ◽  
Concrete Beams ◽  
Plane Section ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Flexural Behavior ◽  
Flexural Capacity ◽  
Aggregate Concrete

This paper presents the results of research on the flexural behavior of recycled aggregate concrete (RAC) beams. The correlation between flexural behavior and the corrosion level of longitudinal rebar was analysed. Based on theoretical analysis and experiment results, the influence of corrosion on flexural cracking moment was analysed and a model to predict the residual flexural capacity of RAC beams with corroded longitudinal rebars was established. The experimental results show that the development degree of cover cracks deepens with the increase of the corrosion level, and the experimental data also demonstrate that the strain distribution of concrete in the midspan of beams conforms to the plane section assumption better when the corrosion level is little but no longer satisfies the plane section assumption when the corrosion level is high.

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