scholarly journals The Flexural and Compressive Strength of Recycled Concrete

2018 ◽  
Vol 2 (1) ◽  
pp. 24-27
Author(s):  
Nouf Jassim Alsabbagh
Keyword(s):  
Compressive Strength ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Partial Replacement ◽  
Experimental Program ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Sustainable Solutions ◽  
Coarse Aggregates ◽  
Construction And Demolition Wastes

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.

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

2020 ◽  
Vol 9 (2) ◽  
pp. 321-326
Keyword(s):  
Compressive Strength ◽  
Load Ratio ◽  
Shear Capacity ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Partial Replacement ◽  
Age Group ◽  
Shear Span ◽  
Coarse Aggregates ◽  
The Relationship

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.

Ultrasonic Test on Recycled Concrete: Relationship among Ultrasonic Waves Velocity, Compressive Strength and Elastic Modulus

2014 ◽  
Vol 894 ◽  
pp. 45-49 ◽  
Author(s):  
Luisa Pani ◽  
Lorena Francesconi
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Ultrasonic Wave ◽  
Ultrasonic Test ◽  
Ultrasonic Waves ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Experimental Program ◽  
Static Modulus ◽  
Cylindrical Samples

In this paper an experimental program has been carried out in order to compare compressive strength fcand elastic static modulus Ecof recycled concrete with ultrasonic waves velocity Vp, to establish the possibility of employing nondestructive ultrasonic tests to qualify recycled concrete. 9 mix of concrete with different substitution percentage of recycled aggregates instead of natural ones and 27 cylindrical samples have been made. At first ultrasonic tests have been carried out on cylindrical samples, later elastic static modulus Ecand compressive strength fchave been experimentally evaluated. The dynamic elastic modulus Edhas been determined in function of ultrasonic wave velocity Vp; furthermore the correlations among Ed, Ec, fce Vphave been determined. It has been demonstrated that ultrasonic tests are suitable for evaluating different deformative and resisting concrete performances even when variations are small.

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 Long-term performance of sustainable pavements using ternary blended concrete with recycled aggregates

2021 ◽  
Author(s):  
Gilson Lomboy ◽  
Douglas Cleary ◽  
Seth Wagner ◽  
Yusef Mehta ◽  
Danielle Kennedy ◽  
...  
Keyword(s):  
Portland Cement ◽  
Cementitious Materials ◽  
Recycled Concrete ◽  
Supplementary Cementitious Materials ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Concrete Aggregates ◽  
Concrete Mixtures

Dwindling supplies of natural concrete aggregates, the cost of landfilling construction waste, and interest in sustainable design have increased the demand for recycled concrete aggregates (RCA) in new portland cement concrete mixtures. RCA repurposes waste material to provide useful ingredients for new construction applications. However, RCA can reduce the performance of the concrete. This study investigated the effectiveness of ternary blended binders, mixtures containing portland cement and two different supplementary cementitious materials, at mitigating performance losses of concrete mixtures with RCA materials. Concrete mixtures with different ternary binder combinations were batched with four recycled concrete aggregate materials. For the materials used, the study found that a blend of portland cement, Class C fly ash, and blast furnace slag produced the highest strength of ternary binder. At 50% replacement of virgin aggregates and ternary blended binder, some specimens showed comparable mechanical performance to a control mix of only portland cement as a binder and no RCA substitution. This study demonstrates that even at 50% RCA replacement, using the appropriate ternary binder can create a concrete mixture that performs similarly to a plain portland cement concrete without RCA, with the added benefit of being environmentally beneficial.

Structural behavior of recycled aggregates concrete filled steel tubular columns

2017 ◽  
Vol 8 (1) ◽  
pp. 17 ◽  
Author(s):  
Boshra Eltaly ◽  
Ahmed Bembawy ◽  
Nageh Meleka ◽  
Kameel Kandil
Keyword(s):  
Finite Element ◽  
Steel Tube ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Experimental Program ◽  
Element Analysis ◽  
Finite Element Program ◽  
Tubular Columns ◽  
Coarse Aggregates ◽  
Element Program

This paper presents an experimental and numerical investigation to determine the behavior of steel tubular columns filled with recycled aggregates concrete up to failure under constant axial compression loads. The experimental program included two steel tube columns, four recycled concrete columns and eight composite columns filled with different types of recycled coarse aggregates (granite and ceramic). Different percentages of recycled coarse aggregates: 0, 25 and 50 of the percentage of the coarse aggregates (dolomite) were used. The results of the numerical model that was employed by the finite element program, ANSYS, were compared with the experimental results. The results of the experimental study and the finite element analysis were compared with the design equations using different national building codes: AISC1999, AISC2005 and EC4. The results indicated that the recycled aggregates concrete infill columns have slightly lower but comparable ultimate capacities compared with the specimens filled with normal concrete.

Study of Durability of Recycled Concrete under the Environment of the Acid Rain

2011 ◽  
Vol 71-78 ◽  
pp. 5042-5045 ◽  
Author(s):  
Xiao Xiong Zha ◽  
Jun Kai Lu
Keyword(s):  
Portland Cement ◽  
Mass Loss ◽  
Acid Rain ◽  
Experimental Studies ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Crushing Strength ◽  
Recycled Concrete Aggregates

Due to the rough surface of the recycled concrete aggregates, low modulus of elasticity and large porosity, these properties led to that the apparent density, strength, physical properties and durability of the recycled concrete made by recycled aggregates are different from the Portland cement concrete, so that the standards and requirements formed about the Portland cement concrete are not entirely suitable for the recycled concrete. On the basis of the experimental studies, this paper analyzes the differences of mass loss, crushing strength and neutralization depth between the ordinary Portland concrete and recycled concrete under the influence of simulation acid rain. The results showed that there are different degrees of change between the concrete with 100% aggregates instead of recycled aggregates and the Portland concrete in mass loss, crushing strength and neutralization depth under the influence of simulation acid rain.

scholarly journals An Experimental Research On Partial Replacement Of Coarse Aggregate with Recycled Aggregate and Fine Aggregate with Granite Powder

2019 ◽  
Vol 8 (9S2) ◽  
pp. 72-77
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Partial Replacement ◽  
Fine Aggregate ◽  
Age Group ◽  
Split Tensile Strength ◽  
Coarse Aggregates ◽  
Granite Powder

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.

scholarly journals Development of Concrete Incorporating Recycled Aggregates, Hydrated Lime and Natural Volcanic Pozzolan

2021 ◽  
Vol 6 (11) ◽  
pp. 155
Author(s):  
Natividad Garcia-Troncoso ◽  
Bowen Xu ◽  
Wilhenn Probst-Pesantez
Keyword(s):  
Compressive Strength ◽  
Recycled Concrete ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Partial Replacement ◽  
Demolition Waste ◽  
Crushed Concrete ◽  
Natural Pozzolana ◽  
Concrete Materials

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.

A Study on the Use of Construction Wastes as Coarse Aggregates on High Performance Concrete

2010 ◽  
Vol 163-167 ◽  
pp. 1525-1531
Author(s):  
Chung Ming Ho ◽  
Wei Tsung Tsai
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Mechanical And Thermal Properties ◽  
Loss On Ignition ◽  
Coarse Aggregates ◽  
Flow Test ◽  
Water To Cement Ratio

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.

scholarly journals Study of the Compressive Strength of Concrete with Partial Replacement of Recycled Coarse Aggregates

2021 ◽  
Vol 11 (3) ◽  
pp. 7191-7194
Author(s):  
X. H. Vu ◽  
T. C. Vo ◽  
V. T. Phan
Keyword(s):  
Compressive Strength ◽  
Recycled Aggregate ◽  
Concrete Mixture ◽  
Recycled Aggregates ◽  
Partial Replacement ◽  
Replacement Rate ◽  
Coarse Aggregates ◽  
Compressive Strength Of Concrete ◽  
Natural Aggregates

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.

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