scholarly journals Long Term Impact in Reinforced Recycled Concrete Beams Under 9-Month Loading

2019 ◽  
Vol 9 (3) ◽  
pp. 4140-4143
Author(s):  
M. Oad ◽  
A. H. Buller ◽  
B. A. Memon ◽  
N. A. Memon ◽  
S. Sohu
Keyword(s):  
Urban Areas ◽  
Concrete Beams ◽  
Testing Machine ◽  
Maximum Load ◽  
Point Load ◽  
Recycled Concrete ◽  
Partial Replacement ◽  
Green Concrete ◽  
Coarse Aggregates

Green concrete is an active area of research. Structural demolishing waste is a global serious problem, particularly in urban areas. This research paper presents the experimental evaluation of the effect of long term loading on reinforced green concrete beams. Three beams were cast with partial replacement of natural coarse aggregates with demolished old concrete. Three beams were cast with all-natural coarse aggregates to compare the results. The beams were mounted on purpose made frames for 9 months. Deflection, strain and cracking in beams were monitored on a daily basis. After 9 months, the beams were tested until failure in a universal load testing machine under central point load. It was observed that the proposed beams exhibited 3.55% reduction in maximum load caring capacity compared to control specimens. The obtained results show good performance of the proposed green concrete beams under 9-month long term loading.

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 Water-Cement Ratio on Flexural Strength of RC Beams Made with Partial Replacement of Coarse Aggregates with Coarse Aggregates from Old Concrete

2019 ◽  
Vol 9 (1) ◽  
pp. 3826-3831
Author(s):  
M. Oad ◽  
A. H. Buller ◽  
B. A. Memon ◽  
N. A. Memon ◽  
Z. A. Tunio ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Flexural Strength ◽  
Concrete Beams ◽  
Recycled Concrete ◽  
Reinforced Concrete Beams ◽  
Partial Replacement ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Coarse Aggregates ◽  
Effect Of Water

This research paper presents an experimental evaluation of the effect of water-cement ratio on the flexural strength of reinforced concrete beams made with 50% replacement of coarse aggregates with recycled concrete aggregates (RCA). 72 reinforced concrete beams were cast using 0.54, 0.6, 0.65 and 0.70 water-cement ratio. In each ratio, 12 beams were cast using RCA and 3 beams were cast using all-natural coarse aggregates (NCA). Beams were cured for 7 and 28 days. After curing, all beams were tested with central point load in a universal load testing machine. From the obtained results, it is observed that the maximum reduction in flexural strength of RCA beams is about 28% when compared to the 0.54 w/c ratio beams of the same group and 31.75% in comparison to NCA beams cast with same w/c ratio. The maximum deflection and average strain in beams remained within limits. The observed cracking pattern shows shear failure of all beams.

scholarly journals Flexural Stress-Strain Behavior of RC Beams Made with Partial Replacement of Coarse Aggregates with Coarse Aggregates from Old Concrete: Part-1: 1:2:4 Ratio

2018 ◽  
Vol 8 (3) ◽  
pp. 3048-3053 ◽  
Author(s):  
M. Oad ◽  
A. H. Buller ◽  
B. A. Memon ◽  
N. A. Memon
Keyword(s):  
Reinforced Concrete ◽  
Urban Areas ◽  
Concrete Beams ◽  
Research Work ◽  
Reinforced Concrete Beams ◽  
Partial Replacement ◽  
Flexural Stress ◽  
Stress Strain ◽  
Strain Behavior ◽  
Coarse Aggregates

Occupancy, particularly in urban areas, requires more space than ever. Space constraints need erection of high rise buildings in place of short height buildings. This need demolishing of old structures which creates huge quantities of demolished concrete. One of its best disposals is its use in new concrete. Therefore, this research work uses 50% replacement of natural coarse aggregates with coarse aggregates from old concrete to study the flexural stress-strain behavior of reinforced concrete beams. Total of 12 reinforced concrete beams (900x150x150 mm) were cast with 2#4 bars in tension and 2#4 bars in compression zones. Ordinary Portland cement with hill sand and crush aggregate was used in 1:2:4 proportions. Water cement ratio used is 0.54. The beams were cast in two batches, one with 100% natural aggregates and another with 50% natural coarse aggregates replaced with coarse aggregates from old concrete. In each batch 3 beams were cured for 7 and 28 days respectively. After curing all beams were tested with central point load. The beams were monitored at regular intervals for load, displacement, strain and load until first crack. The beams under study were compared with the controlled specimen. The results were in good agreement with the normal concrete specimen. Maximum reduction in flexural stress is recorded as 8.8% for 7-day cured beams and 5.52% for 28-day cured specimen. Thus, the use of coarse aggregates from demolished concrete in new concrete is proved to be promising partial replacement of coarse aggregate in terms of flexural stress-strain relationship.

scholarly journals Impact of Long-Term Loading on Reinforced Concrete Beams Made with Partial Replacement of Coarse Aggregates with Recycled Aggregates from Old Concrete

2019 ◽  
Vol 9 (1) ◽  
pp. 3818-3821 ◽  
Author(s):  
M. Oad ◽  
A. H. Buller ◽  
B. A. Memon ◽  
N. A. Memon
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Recycled Concrete ◽  
Reinforced Concrete Beams ◽  
Partial Replacement ◽  
Short Term ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Coarse Aggregates ◽  
Sustained Loading

This research work presents an experimental evaluation of the effect of sustained loading on reinforced concrete beams made with 50% replacement of natural coarse aggregates with aggregates from old concrete. A total of 9 RC beams were cast, 6 with natural coarse aggregates and 3 with recycled concrete aggregates. All beams were cured for 28 days in standard fashion. Among the first batch, 3 beams were used to test under short term loading till failure. An application of 50% of short-term loading followed on all beams assembled on purpose made frames. All beams were monitored for deflection, strain, and cracking. Both deflection and strain remained within limits. Crack monitoring revealed maximum crack width 0.5 mm. After six months of sustained load, beams were removed from the frames and tested in universal load testing machine with central point load till failure. The load-deflection pattern of all beams was observed to be almost similar and 22.12% higher in recycled concrete beams than all-natural aggregate beams. The results show promising use of recycled concrete aggregates in new concrete subjected to sustained loading.

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%.

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

Experimental Research on Behavior of Composite Beams of Steel-Reinforced Recycled Concrete

2013 ◽  
Vol 639-640 ◽  
pp. 145-148 ◽  
Author(s):  
Yan Dong Jia ◽  
Ying Kai Guo ◽  
Zhi Ping Sun ◽  
Xin Zhao
Keyword(s):  
Composite Structures ◽  
Coarse Aggregate ◽  
Concrete Beams ◽  
Failure Process ◽  
Limit Load ◽  
Maximum Load ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Cement Slurry ◽  
Recycled Coarse Aggregate

The recycled aggregate is dealt with in three ways, the first way is to keep the recycled aggregate intact; the second way is to wrap the recycled aggregate in cement slurry of Water-cement ratio 0.55 for 30 minutes, and then place it at room temperature for 7 days; the third way is to immerse the recycled aggregate in water for 24 hours. Three kinds of different recycled aggregate is separately used for mixing of recycled concrete. The strength and slump of recycled concrete with different recycled coarse aggregate contents are tested. Experiments show that the recycled concrete produced by using the recycled aggregate immersed in water and selecting a suitable mix has the higher strength and slump，which can be industrialized. And then, the recycled concrete with 40% recycled coarse aggregate contents is used in the steel-reinforced recycled concrete beams, which are tested, the failure process of steel-reinforced recycled concrete beams,section strains and maximum load are acquired. Research shows the steel-reinforced recycled concrete beams conform to plane hypothesis before the load reachs 80% the limit load, the flexural bearing capacity of the steel-reinforced recycled concrete beams can meet the demand of Technichal Specification of Steel-Reinforced Concrete Structures. The use of recycled concrete in the composite structures is proposed.

scholarly journals Flexural Behavior of Reinforced RAC Beams Exposed to 1000°C Fire for 18 Hours

2019 ◽  
Vol 9 (3) ◽  
pp. 4225-4229
Author(s):  
A. H. Buller ◽  
M. Oad ◽  
B. A. Memon
Keyword(s):  
Shear Failure ◽  
Research Work ◽  
Testing Machine ◽  
Point Load ◽  
Recycled Aggregate ◽  
Flexural Behavior ◽  
Load Testing ◽  
Test Results ◽  
Coarse Aggregates ◽  
Fast Pace

In order to meet the socio-economic demands around the globe, construction industry not only consumes concrete at a very fast pace but also yields huge amounts of construction and demolishing waste. The phenomenon gives rise to environmental issues due to production of concrete ingredients and due to dumping of the waste. Therefore, one of the solutions is the production of green concrete utilizing demolished waste. This research work studies the effect of prolonged fire (18 hours) on the flexural behavior of reinforced concrete–recycled aggregate beams. The beams were using 50% replacement of natural coarse aggregates with demolished concrete. The beam samples were cast as both normal and rich mix concrete and were cured for 28 days. After curing, the beams were exposed to fire at 1000°C in a purpose made oven, followed by testing in a universal load testing machine under central point load. The test results show that the proposed beams (cast with rich mix) exhibited about 22% reduction in flexural strength. The failure mode of the beams was observed as shear failure.

scholarly journals Experimental study of concrete prepared by kota stone dust, bagasse ash, and recycled concrete

2021 ◽  
Vol 889 (1) ◽  
pp. 012040
Author(s):  
Harshdeep Vani ◽  
Sahil Arora
Keyword(s):  
Experimental Study ◽  
Cost Analysis ◽  
Cost Reduction ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Green Concrete ◽  
Coarse Aggregates ◽  
Gas Formation ◽  
Stone Dust ◽  
The Cost

Abstract This paper mainly deals with the cost analysis of the concrete which is prepared using environmental waste which forms pollution and having its disposable issue also. This concrete may be termed as green concrete because the use of these materials decreases the harmful gas formation of the concrete. This paper deals with Kota Stone Dust, Bagasse Ash, and Recycled coarse aggregates. The concrete is prepared by the various ratios of Kota Stone in order of 5%, 10%, 15%, 20%, 25% and 30%. The use of bagasse ash was done in ratio 10%, 20%, 30%, 40% and use of Recycled Aggregate was done in ratio of 10%, 20%, 30% and 40%. After the successful experimental study of concrete using this material the cost reduction for M25 grade of concrete was found to be 645 INR.

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