scholarly journals Experimental Inspection on Shear Capacity in RCC Beams with Partial Replacement of Recycled Coarse Aggregates

Demolition waste increasing day by day. The old damaged building materials can be used in present buildings or other construction works. Especially the recycled aggregates are useful to the concrete structures. The experimental studies on the use of recycled coarse aggregate has been going on for many countries. This publication focuses on the relationship between the shear capacity and the flexural cracking load of reinforced recycled concrete beams with stirrups, this experimental Inspection with partial replacement of natural coarse aggregates (NAC) with recycled coarse aggregates (RAC) at different ages as 10, 20 and 30 years in various proportions as 20 per cent, 30 per cent, 40 per cent. For this, M30 grade of concrete is consider. Curing of specimens were done for 7 day and 28 days to conclude the maximum strengths. The obtained results of concrete with partial replacement of recycled aggregates of 10,20and 30 years age group conclude maximum compressive strength of 35.84 N/mm2 at 40% replacement of NCA with RCA of age group (10 years) and 34.12 N/mm2 at 30% replacement of NCA whit RCA of (20 years) age group and 36.14 N/mm2 20% replacement of NCA with RCA of age group (30 years). After the compressive strength, beam specimens were casted for 7day and 28 days. Based on test results of 8 beams, the relationship between the cracking load that causes a beam to crack in the middle of the shear span and the beam's shear capacity is confident. All beams are reinforced in the longitudinal direction only and only tested under two-point loading conditions. The average analytical cracking load ratio is 0.60.the mid-shear span at cracking load (Vcr-a/2) in comparison with the observed shear capacity (Vexp). The analytical cracking load ratio. The analytical cracking’s load was used in this exploration as it is more reliable than the observed cracking load. At mid-span, the shear capacity of most of the beams was shown to be 50%. The average shear capacity ratio to the related test crack load in the center of the shear span 0.43. The analysis showed that cracking loads are strongly related to the shear capacity of the members. This relationship can be used to develop recycled reinforced beam members ' shear design process.

Now a days increase in population increases the demand of concrete for construction purpose and Aggregates are the important constituents in concrete.Re-use of demoliation waste avoids the problem of waste disposal and is also helpful in reducing the gap between demand and supply of fresh aggregates. This research deals with partial replacement of natural coarse aggregates (NCA) with recycled coarse aggregates (RCA) of age group 30 years and 35 years in different proportions like 20%, 30%, 40% . For this, M20 grade of concrete is adopted. Curing of specimens were done for 7days and 28 days to attain the maximum strengths. Partial replacement of fine aggregate with Granite powder at 5%, 10%, 15% were done to reduce the waste percentage as well to gain more strength. After casting the specimens of RCA with Granite powder replacement, curing was done and the specimens were tested for compressive and tensile strengths. Obtained results of compressive and tensile strengths of RCA concrete mix were compared with conventional concrete. In this direction, an experimental investigation of compressive and tensile strength was undertaken to use RCA as a partial replacement in concrete. It was observed that the concrete with recycled aggregates of 30years and 35years age group achieved maximum compressive strength of 29.03 N/mm2 , 28.96 N/mm2 and tensile strength of 11.91 N/mm2 , 10.34 N/mm2 were obtained at 40%replacement of RCA respectively. It is found that the compressive strength and Split tensile strength of RAC with copper slag was increased 8.20% and 2.90% when compared with the RAC.


2018 ◽  
Vol 2 (1) ◽  
pp. 24-27
Author(s):  
Nouf Jassim Alsabbagh

Limitations in natural resources have drawn the necessity to develop sustainable solutions for the future of the concrete industry. Kuwait has joined the world’s effort to encourage recycling by reducing the amounts of construction and demolition wastes sent to landfills, through the usage of recycled aggregates in Portland Cement concrete mixes. In this research, an experimental program was designed to test the effect of substituting virgin coarse aggregates with recycled aggregates obtained from demolished concrete. Four different concrete mixes were designed at a strength of 30MPa, with different partial replacement percentages of 100%, 50%, and 0%. All mixes were tested for workability. Samples were cast from each mix and tested for the flexural strength as well as the compressive strength; all results were compared to a control mix. Results demonstrated that in spite of the slight effect noted on both flexural and compressive strength, good quality concrete can still be achieved.


2020 ◽  
Vol 10 (3) ◽  
pp. 5728-5731 ◽  
Author(s):  
S. A. Chandio ◽  
B. A. Memon ◽  
M. Oad ◽  
F. A. Chandio ◽  
M. U. Memon

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%.


2011 ◽  
Vol 324 ◽  
pp. 348-351 ◽  
Author(s):  
Rouba El Dalati ◽  
Pierre Matar ◽  
Sara Haddad ◽  
Fadi Hage Chehade

Concrete recycling consists of crushing the concrete provided by demolishing the old constructions, and of using the resulted small pieces as aggregates in the new concrete compositions. The resulted aggregates are called recycled aggregates and the new mix of concrete containing a percentage of recycled aggregates is called recycled concrete. Our previous researches have indicated the optimal percentages of recycled aggregates to be used for different cases of recycled concrete related to the original aggregates nature. All results have shown that the concrete compressive strength is significantly reduced when using recycled aggregates. In order to obtain realistic values of compressive strength, some tests have been carried out by adding water-reducer plasticizer and a specified additional quantity of cement. The results have shown that for a limited range of plasticizer percentage, and a fixed value of additional cement, the compressive strength has reached reasonable value. This paper treats of the effect of using recycled aggregates on the tensile strength of concrete, where concrete results from the special composition defined by our previous work. The aim is to determine the relationship between the compressive and tensile strength of recycled concrete.


2021 ◽  
Vol 6 (11) ◽  
pp. 155
Author(s):  
Natividad Garcia-Troncoso ◽  
Bowen Xu ◽  
Wilhenn Probst-Pesantez

Recycling of construction and demolition waste is a central point of discussion throughout the world. The application of recycled concrete as partial replacement of mineral aggregates in concrete mixes is one of the alternatives in the reduction of pollution and savings in carbon emissions. The combined influence of the recycled crushed concrete, lime, and natural pozzolana on the mechanical and sustainable properties of concrete materials is firstly proposed in this study. In this research, unconventional construction materials are employed to produce concrete: the recycled crushed concrete is used as coarse aggregate, while lime and natural pozzolana are used as a partial replacement for cement. Substitutions of 10%, 20%, 50% of gravel are made with recycled aggregates, and 2%, 5%, 10% of cement with lime and natural pozzolan. Tests on the fresh and hardened properties, destructive (compressive strength) and non-destructive tests (sclerometer rebound and ultrasound) of mixtures are carried out. It is shown that the use of recycled materials can provide an increase in compressive strength of up to 34% with respect to conventional concrete. Life cycle cost and sustainability assessments indicate that concrete materials incorporating recycled aggregate possess good economic and environmental impacts.


2010 ◽  
Vol 163-167 ◽  
pp. 1525-1531
Author(s):  
Chung Ming Ho ◽  
Wei Tsung Tsai

In recent years, because of rising consciousness on environmental protection and the lacking of construction waste dumping yards, recycling of construction wastes has been promoted extensively. The purpose of this study is to ascertain the effect on properties of the fresh and harden concrete replacing coarse aggregates by construction wastes under ambient and enhanced temperatures exposure. This research mainly concentrates on high performance recycled concrete (HPRC); by adding different amount of superplasticizer into the HPRC and to test and compare its mechanical and thermal properties with general high performance concrete (HPC). Thereafter, tests are carried out determine its compressive strength, residual strength after high temperature and the loss on ignition of the HPRC mixed with two water-to-cement ratios and different replacement proportions of recycled aggregates. Similar tests, such as the slump test and slump flow test, are carried out both on the HPRC and HPC. When the water-to-cement ratio is 0.3 and the amount of superplasticizer added is 1.2%, HPRC has the best performance. The specimens with 100% recycled aggregates were 31% below the control concrete sample in compressive strength at age of 28 days. By the way of adding admixture, the recycled concrete could reach the demand strength of the HPC. The results show that it is feasible to allow a higher replacement percentage of construction wastes for producing concrete products.


2021 ◽  
Vol 11 (3) ◽  
pp. 7191-7194
Author(s):  
X. H. Vu ◽  
T. C. Vo ◽  
V. T. Phan

This paper presents a study on the compressive strength of concrete using recycled aggregates. The concrete was designed to have a 25MPa compressive strength and an 8cm slump. The rates of replacing natural aggregates with recycled coarse were 0%, 10%, and 20%. The test samples were compressed to determine their compressive strength value after 7, 14, and 28 days of curing. The results showed that the concrete slump did not change effectively at a 10% replacement rate. When using 20% recycled aggregates, the concrete was too hard and the homogeneity of the concrete mixture could not be guaranteed. The compressive strength slightly decreased using 10% of recycled aggregates and decreased significantly using 20%. Therefore, 20% of recycled aggregate replacement is not suitable. The results showed that using recycled aggregates at a rate of 10% is optimal.


Author(s):  
Khaoula Naouaoui ◽  
Azzeddine Bouyahyaoui ◽  
Toufik Cherradi

Recycled aggregate concrete is considered the next generation in the field of construction: it respects the environment, solves the problem of debris management and is economically profitable. In order to better adapt its use, technical studies, experimental studies and simulations are carried out in all research centers around the world in order to define its field of application. Our study falls within this framework. It is concerned with the study of the mechanical characteristics of recycled aggregate concrete essentially the compression test for various percentages of replacement. The purpose of this study is to confirm the results of studies by other researchers and to find techniques that will maximize the replacement of natural aggregates with recycled aggregates. The concrete chosen for these tests is an old building in the region of Rabat, Morocco which has been built more than 40 years and demolished in the year of 2017. The tests carried out showed a decrease in the compressive resistance noted when the replacement rates exceed 50% rate. The first improvement methods were put in place and being tested: the partial replacement of cement with pozzolan (20% rate) known by his improving of the compressive strength for ordinary concrete, the partial replacement of the large proportion [12.5-31.5] only in recycled concrete and work with natural gravels. Other improvements will be proposed as the studies progress.


2018 ◽  
Vol 4 (10) ◽  
pp. 2305 ◽  
Author(s):  
Naraindas Bheel ◽  
Shanker Lal Meghwar ◽  
Samiullah Sohu ◽  
Ali Raza Khoso ◽  
Ashok Kumar ◽  
...  

Concrete is highly utilized construction material around the globe and responsible for high depreciation of the raw materials. Consumption of this material in construction industry is arching upward day by day. On the other hand, debris of demolished concrete structures are being dumped as waste. For developing countries such waste is not a good sign and need its proper utilization by recycling it into useful product. In this consequence, this study is an attempt to utilize demolished waste concrete by converting into coarse aggregates. This research was conducted on recycled cement concrete aggregates of demolished structures and Rice Husk Ash (RHA). The purpose of this experimental study is to analyze the mechanical properties of concrete; when cement is partially replaced with RHA and natural aggregates by recycled aggregates (RA). In this study, the cement was replaced by RHA up to 10% by weight of cement. For experimental purpose, total 135 concrete specimens were prepared, cured and tested in Universal Testing Machine (UTM). Finally, laboratory results were compared in terms of compressive and splitting tensile strength made with normal and recycled coarse aggregates. All the specimens were prepared at 1:1.5:3 with 0.50 w/c ratio and tested at 7, 14, 21, 28 and 56 days curing ages. It is observed from experimental analysis that the workability of fresh normal concrete is 7% and 10% greater than recycled aggregates concrete blended with 10% RHA and only recycled aggregates concrete without RHA respectively. The compressive strength increases up to 6%, whilst splitting tensile strength increases 4% at 56 days curing, when the cement is replaced 10% by RHA. It is, further, concluded that with more than 10% RHA replacement with cement, the compressive strength decreases. This study would help the construction experts to use such wasted concrete into useable production of new concrete projects.


Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 340
Author(s):  
Parthiban Kathirvel ◽  
Gunasekaran Murali ◽  
Nikolai Ivanovich Vatin ◽  
Sallal R. Abid

It appears that the awareness and intentions to use recycled concrete aggregate (RCA) in concrete are expanding over the globe. The production of self-compacting concrete (SCC) using RCA is an emerging field in the construction sector. However, the highly porous and absorptive nature of adhered mortar on RCA’s surface leads to reduced concrete strength, which can be removed with the application of various techniques, such as acid treatment. This study investigated the effect of the partial replacement of silica fume by cement and natural aggregate (NA) by RCA with and without steel fibre. The used RCA was treated with magnesium sulphate solution. It was immersed in solutions with different concentrations of 10%, 15% and 20% and for different periods of 5, 10 and 15 days. Sixteen mixes were prepared, which were divided into six groups with or without 1% of steel fibre content. The fresh properties, compressive strength, split tensile strength and impact resistance were examined. The results revealed that the strengths of the mixes with 20% RCA were marginally better than those of the control mixes. The compressive strength and split tensile strength were reduced by 34% and 35% at 60% RCA content, respectively, as compared to the control mixes.


Sign in / Sign up

Export Citation Format

Share Document