scholarly journals Flexural Behavior of RC Beams Made with Recycled Aggregates Under 12-Month Long Term Loading

2019 ◽  
Vol 9 (5) ◽  
pp. 4631-4635
Author(s):  
M. Oad ◽  
B. A. Memon ◽  
A. H. Buller ◽  
N. A. Memon
Keyword(s):  
Peak Load ◽  
Reinforced Concrete Beams ◽  
Flexural Behavior ◽  
Recycled Aggregates ◽  
Partial Replacement ◽  
Sustained Load ◽  
Infrastructure Development ◽  
Rc Beams ◽  
Coarse Aggregates

In the present era of infrastructure development, demolishing waste management poses serious problems, particularly in urban centers. Vast development requires huge amounts of conventional concrete aggregates resulting in serious environmental problems. Therefore, efforts are carried out in utilizing demolishing waste, particularly demolishing concrete as coarse aggregates used in new concrete. This article presents laboratory investigations of flexural behavior of reinforced concrete beams made with partial replacement of natural coarse aggregates with coarse aggregates from demolished concrete under 12-month long-term loading. Two batches of beams were cast and cured for 28 days. In the first batch three RC beams with partial replacement of natural coarse aggregates were cast, while in the second batch 6 RC beams with all-natural coarse aggregates were prepared. Out of these six beams three beams were tested under short-term loading to determine maximum load. 50% of this load was used as sustained load on the remaining all beams. The beams were mounted on purpose made frames and deflection, strain, and cracking were recorded on daily basis. After the elapse of the defined time the beams were tested under central point load until failure. Result comparison shows a 4.96% increase in deflection and 2.33% reduction in peak load. Based on the results of this study it is concluded that demolished concrete as coarse aggregates in new concrete shows reasonably good performance under 12-month long-term loading.

scholarly journals Long-term Deflections of Hybrid GFRP/Steel Reinforced Concrete Beams under Sustained Loads

2020 ◽  
Vol 6 ◽  
pp. 1-11
Author(s):  
Phan Duy Nguyen ◽  
Vu Hiep Dang ◽  
Ngoc Anh Vu ◽  
Polikutin Aleksei Eduardovich
Keyword(s):  
Reinforced Concrete ◽  
Steel Reinforcement ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Flexural Behavior ◽  
Rc Beams ◽  
Climate Conditions ◽  
Glass Fiber Reinforced ◽  
Sustained Loads

One of the solutions to improve the flexural behavior of Glass fiber reinforced polymer (GFRP) reinforced concrete (RC) beams is the addition of tensile longitudinal steel reinforcement. The numerous studies to date on hybrid GFRP/steel RC elements have mainly focused on the static and short-term responses, very little work has been done regarding the long-term performance. This paper presents experimental results of time-dependent deflections of cracked GFRP and hybrid GFRP/steel RC beams during a 330-day-period in natural climate conditions. Three hybrid GFRP/steel and one GFRP RC beams with dimensions 100×200×2000 mm were tested in four-point bending. Different steel reinforcement ratios were used to evaluate the effect of the steel reinforcement on the long-term behavior of the beams. Experimental results show that the immediate deflections are inversely proportional to the additional steel reinforcement. With the same initial instantaneous deflection, the total deflection increases when increasing the steel reinforcement ratio. Also, temperature (T) and relative humidity (RH) significantly affect the long-term deflection of the tested beams. The measured long-term deflections were found to be in good agreement with the theoretical values calculated from the proposed method. However, there was an overestimation when using ACI 440.1R-15 or CSA-S806-12 procedures.

scholarly journals Effect of 12-hour fire on Flexural Behavior of Recyclable Aggregate Reinforced Concrete Beams

2019 ◽  
Vol 5 (7) ◽  
pp. 1533-1542 ◽  
Author(s):  
Abdul Hafeez Buller ◽  
Bashir Ahmed Memon ◽  
Mahboob Oad
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Research Work ◽  
Testing Machine ◽  
Point Load ◽  
Reinforced Concrete Beams ◽  
Flexural Behavior ◽  
Partial Replacement ◽  
Load Testing ◽  
Coarse Aggregates

Fire being one of the hazards causes external and internal adverse effects on concrete. On the other hand, demolishing waste causes numerous environmental issues due to lack of proper disposal management. Therefore, this research work presents experimental evaluation of effect of 12-hur fire on flexural behavior of reinforced concrete beams made with partial replacement of natural coarse aggregates with coarse aggregates from demolished concrete. The model beams are prepared using both normal and rich mix. Natural coarse aggregates are replaced in 50% dosage. Also, the beams without recyclable aggregates are prepared to check the results of proposed beams. After 28-day curing all the beams are exposed to fire for 12-hour at 1000°C in purpose made oven, followed by testing in universal load testing machine under central point load. During the testing deflection, load, and cracks are monitored. Analysis of flexural behavior and cracking reveals that after 12-hour fire residual strength of the beams is 52%. This shows loss of the strength of reinforced concrete beams thus requires appropriate retrofitting decision before putting again the structure in service after fire. Observation of cracks shows that most of the beams failed in shear with minor flexural cracks. In comparison to the results of control specimen the proposed beams show good fire resistance. The outcome of the research will prove landmark for future scholars and help the industry personals in understanding the behavior of the material in fire.

scholarly journals 24-hour Fire Produced Effect on Reinforced Recycled Aggregates Concrete Beams

2019 ◽  
Vol 9 (3) ◽  
pp. 4213-4217 ◽  
Author(s):  
A. H. Buller ◽  
M. Oad ◽  
B. A. Memon ◽  
S. Sohu
Keyword(s):  
Flexural Strength ◽  
Concrete Beams ◽  
Testing Machine ◽  
Maximum Load ◽  
Reinforced Concrete Beams ◽  
Recycled Aggregates ◽  
Equal Proportion ◽  
Load Testing ◽  
Coarse Aggregates ◽  
Natural Aggregates

In this article, the effect of prolonged fire (24-hour duration) on reinforced concrete beams made with recycled aggregates from demolished concrete was experimentally investigated. Demolished concrete was used recycled coarse aggregates in equal proportion with natural coarse aggregates. Normal and rich mix concrete with water-cement ratio equal to 0.54 were used. As a control specimen, beams with all-natural aggregates were also cast to compare with the results of the proposed beams. All beams were cured for 28 days and exposed to fire at 1000°C in an oven for 24 hours. After the elapse of this fire period, the beams were allowed to air cool, followed by testing till failure in a universal load testing machine. Comparison of the test results shows that rich mix concrete beams more reduction in flexural strength, more increase in maximum load carrying capacity and deflection than normal mix beams. The maximum reduction in flexural strength was 32.41% for beams cast with 50% RCA and rich mix. Although the fire duration used in this study is rare, yet the outcome provides guidelines for taking proper decisions for retrofitting/strengthening of the fire affected structure before putting it back in service.

scholarly journals Effect of Fly Ash on the Compressive Strength of Green Concrete

2020 ◽  
Vol 10 (3) ◽  
pp. 5728-5731 ◽  
Author(s):  
S. A. Chandio ◽  
B. A. Memon ◽  
M. Oad ◽  
F. A. Chandio ◽  
M. U. Memon
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Recycled Aggregates ◽  
Waste Materials ◽  
Partial Replacement ◽  
Equal Proportion ◽  
Standard Size ◽  
Green Concrete ◽  
Coarse Aggregates ◽  
Management Issues

This research paper aims at investigating the effects of fly ash as cement replacement in green concrete made with partial replacement of conventional coarse aggregates with coarse aggregates from demolishing waste. Green concrete developed with waste materials is an active area of research as it helps in reducing the waste management issues and protecting the environment. Six concrete mixes were prepared using 1:2:4 ratio and demolishing waste was used in equal proportion with conventional aggregates, whereas fly ash was used from 0%-10% with an increment of 2.5%. The water-cement ratio used was equal to 0.5. Out of these mixes, one mix was prepared with all conventional aggregates and was used as the control, and one mix with 0% fly ash had only conventional and recycled aggregates. The slump test of all mixes was determined. A total of 18 cylinders of standard size were prepared and cured for 28 days. After curing the compressive strength of the specimens was evaluated under gradually increasing load until failure. It is observed that 5% replacement of cement with fly ash and 50% recycled aggregates gives better results. With this level of dosage of two waste materials, the reduction in compressive strength is about 11%.

scholarly journals Effect of loading rate on flexural behavior of concrete and reinforced concrete beams

2021 ◽  
Vol 15 (3) ◽  
pp. 136-143
Author(s):  
Nguyen Trung Hieu ◽  
Nguyen Van Tuan
Keyword(s):  
Reinforced Concrete ◽  
Loading Rate ◽  
Plain Concrete ◽  
Reinforced Concrete Beams ◽  
Flexural Behavior ◽  
Displacement Curve ◽  
Rc Beams ◽  
Three Point Bending ◽  
Loading Rates ◽  
Hydraulic Servo

The elasto-plastic characteristics of plain concrete are inevitably affected by the loading rate. This paper presents an experimental investigation on the effect of loading rate on flexural behavior of concrete and reinforced concrete (RC) beams, which was carried out with Walter+bai electro-hydraulic servo system. Three-point bending tests on 100 × 100 × 400 mm prismatic concrete samples and 80 × 120 × 1100 mm RC beams with different displacement controlled loading rates of 0.01 mm/min, 0.1 mm/min, and 3 mm/min were imposed. Based on the test results, the effects of loading rates on the load-displacement curve, cracking, and ultimate load-carrying capacities of RC beams were evaluated.

Long-term flexural performance of reinforced concrete beams with recycled coarse aggregates

2018 ◽  
Vol 176 ◽  
pp. 593-607 ◽  
Author(s):  
Sindy Seara-Paz ◽  
Belén González-Fonteboa ◽  
Fernando Martínez-Abella ◽  
Diego Carro-López
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Flexural Performance ◽  
Coarse Aggregates

scholarly journals Experimental Study on the Flexural Behavior of over Reinforced Concrete Beams Bolted with Compression Steel Plate: Part I

2020 ◽  
Vol 10 (3) ◽  
pp. 822 ◽  
Author(s):  
Shatha Alasadi ◽  
Payam Shafigh ◽  
Zainah Ibrahim
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Steel Plate ◽  
Concrete Beams ◽  
Peak Load ◽  
Reinforced Concrete Beam ◽  
Reinforced Concrete Beams ◽  
Steel Plates ◽  
Flexural Behavior ◽  
Flexural Stiffness

The purpose of this paper is to investigate the flexural behavior of over-reinforced concrete beam enhancement by bolted-compression steel plate (BCSP) with normal reinforced concrete beams under laboratory experimental condition. Three beams developed with steel plates were tested until they failed in compression compared with one beam without a steel plate. The thicknesses of the steel plates used were 6 mm, 10 mm, and 15 mm. The beams were simply supported and loaded monotonically with two-point loads. Load-deflection behaviors of the beams were observed, analyzed, and evaluated in terms of spall-off concrete loading, peak loading, displacement at mid-span, flexural stiffness (service and post-peak), and energy dissipation. The outcome of the experiment shows that the use of a steel plate can improve the failure modes of the beams and also increases the peak load and flexural stiffness. The steel development beams dissipated much higher energies with an increase in plate thicknesses than the conventional beam.

Flexural Behavior of High Strength Reinforced Concrete Beams by Replacement Ratio of Recycled Coarse Aggregate

2013 ◽  
Vol 680 ◽  
pp. 230-233 ◽  
Author(s):  
Yong Taeg Lee ◽  
Seung Hun Kim ◽  
Jong Hyeon Kim ◽  
Sang Ki Baek ◽  
Young Sang Cho ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Flexural Strength ◽  
Concrete Beams ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
Flexural Behavior ◽  
Recycled Aggregates ◽  
Current Test ◽  
Potential Applications ◽  
Flexural Tests

Recently, many structures which were built about 30 years ago are watched by reconstruction. Demolished concrete is occurred in the process and these quantity increase about 10% more than the preceding year. Fortunately, recycled aggregates are produced from demolished concrete, whereas the recycled aggregates are not used often because there are not many researches which have been verified by experts or researchers about strength when reinforced concrete is made with recycled aggregates. In this paper, high strength reinforced concrete is valued with potential applications and check change of strength when it made by recycled aggregates. For this, flexural tests of 4 high strength reinforced concrete beams with recycled aggregates were performed, and the high strength reinforced concrete beams were tested within the limits such as compressive strength, flexural strength, ductility, strain, and curvature. The current test data were examined in terms of flexural strength, along with the data from previously tested reinforced concrete beams with recycled aggregates.

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