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.

Meso-Analysis of Dynamic Compressive Behavior of Recycled Aggregate Concrete Using BFEM

2019 ◽  
Vol 17 (06) ◽  
pp. 1950013 ◽  
Author(s):  
Liping Ying ◽  
Yijiang Peng ◽  
Hongming Yang
Keyword(s):  
Mechanical Properties ◽  
High Strain ◽  
Dynamic Mechanical Properties ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Dynamic Mechanical ◽  
Concrete Materials ◽  
Dynamic Damage

In this paper, the base force element method (BFEM) for dynamic damage problems is proposed. And the BFEM model was applied to investigate the dynamic mechanical behavior of recycled aggregate concrete (RAC). Any convex polygon recycled aggregate was simulated. A constitutive relationship of dynamic damage was given. The compression test under dynamic loadings on the recycled concrete specimen was simulated. The stress–strain softening curve, variation law of dynamic enhancement coefficient and the damage pattern were researched under different strain rates. The dynamic properties of recycled concrete materials at high strain rate are also studied. The effect of different aggregate distribution on the mechanical properties of concrete was studied. The results of dynamic calculation of recycled concrete materials by this method are compared with the experimental results. The numerical simulation results are in good agreement with the experimental results. The comparative analysis on the dynamic mechanical properties of RAC and natural aggregate concrete (NAC) was also studied. The results show that the BFEM can be used to analyze the dynamic mechanical properties of RAC and NAC under high strain rate, and can be used for large-scale engineering calculations.

scholarly journals Performance of Recycled Aggregate Concrete for M25 Grade Concrete

2019 ◽  
Vol 9 (2) ◽  
pp. 4694-4700
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Aggregate Concrete ◽  
Inorganic Particles ◽  
Natural Aggregates

Recycled aggregates (RCA) are the aggregates which are made up of crushed, inorganic particles that are obtained from the construction demolition debris. Now a day’s protection of environment is the ultimate challenge to the society. So the usage of RCA’s is the best alternative for the aggregates which are obtained naturally in the construction activity. The scope of using these recycled concrete aggregates is increasing day by day. It reduces the cost effectively as we are using waste concrete as recycled aggregates. The main focus of this paper is to use find the strength qualities of recycled aggregates so as to use it as an alternative for the natural aggregates in high strength concrete for various construction activities. Comparison of workability, compressive strength, tensile strength, elastic modulus and flexural strength of recycled aggregate concrete is made with natural aggregate concrete. Here M25 grade concrete is taken and the natural aggregates were replaced with recycled aggregates in various percentages of 0%, 25%, 50%, 75% and 100%. The mix design for these replacement ratios are done by using code of IS 10262-2009. In order to determine the properties which were mentioned above a total of 60 cubes, 10 beams and 40 cylinders were casted. The compressive strength and tensile strength of RCA concrete have been determined for 7 days and 28 days where as the modulus of elasticity and the flexural strength of RCA concrete are determined after curing for the period of 28 days. The tests done on RCA concrete are compared with concrete which is obtained by natural aggregates As per IS codification the parameters which were determined are reducing moderately as the amount of aggregates which are recycled is being raised

scholarly journals Self-cementing properties of recycled concrete aggregates (RCA) on the example of tests of material and layers of pavement subbase

2014 ◽  
Vol 13 (4) ◽  
pp. 101-107
Author(s):  
Jakub Fengier ◽  
Andrzej Pożarycki
Keyword(s):  
Compressive Strength ◽  
Field Tests ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Concrete Materials

The work is an attempt to summarize the experience concerning the diagnosis of the practical properties of recycled aggregate concrete cement (RCA). It describes the phenomenon of self-cementing properties which was investigated in both the laboratory and on field tests including compressive strength of RCA, non-conventional oedometric tests of RCA and plate bearing tests on the surface of RCA layer. The described self-cementing properties were remarked, however, the RCA material was characterized by smaller increase in the value of parameter EV2 in a 2-year period of time than recycled concrete materials described in the available literature.

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 Laboratory Investigation on the Shrinkage Cracking of Waste Fiber-Reinforced Recycled Aggregate Concrete

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1196 ◽  
Author(s):  
Xiaoxin Wu ◽  
Jinghai Zhou ◽  
Tianbei Kang ◽  
Fengchi Wang ◽  
Xiangqun Ding ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Mechanical Performance ◽  
Volume Fraction ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Fiber Reinforced ◽  
Shrinkage Cracking ◽  
Aggregate Concrete

This paper aims to study the effectiveness of adding waste polypropylene fibers into recycled aggregate concrete (RAC) on shrinkage cracking. The influences of fiber properties (length and content) on the shrinkage performance of RAC are investigated. Firstly, through the plat-ring-type shrinkage test and free shrinkage test, both of the early age and long-term shrinkage performance of waste fiber recycled concrete (WFRC) were measured. Then, X-ray industrial computed tomography (ICT) was carried out to reflect the internal porosity changes of RAC with different lengths and contents of fibers. Furthermore, the compressive strength and flexural strength tests are conducted to evaluate the mechanical performance. The test results indicated that the addition of waste fibers played an important role in improving the crack resistance performance of the investigated RAC specimens as well as controlling their shrinkage behaviour. The initial cracking time, amount and width of cracks and shrinkage rate of fiber-reinforced specimens were better than those of the non-fiber-reinforced specimen. The addition of waste fibers at a small volume fraction in recycled concrete had not obviously changed the porosity, but it changed the law of pore size distribution. Meanwhile, the addition of waste fibers had no significant effect on the compressive strength of RAC, but it enhanced the flexural strength by 43%. The specimens reinforced by 19-mm and 0.12% (volume fraction) waste fibers had the optimal performance of cracking resistance.

Research on the Characteristics and Status of Recycled Concrete Filled Steel Tube

2014 ◽  
Vol 580-583 ◽  
pp. 2320-2323
Author(s):  
Bing Wang ◽  
Xiao Liu ◽  
Xiao Yu
Keyword(s):  
Mechanical Properties ◽  
Environmental Protection ◽  
Steel Tube ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Future Application ◽  
Aggregate Concrete ◽  
Concrete Filled Steel Tube ◽  
Waste Concrete

Utilization of waste concrete has a great significance for environmental protection; concrete filled steel tube is a way of utilization of waste concrete. At the same time, the recycled concrete on the center tube has a "hoop" function, can compensate for the deviation of mechanical properties of recycled aggregate concrete. This paper introduces the characteristics of steel recycled concrete, and introduces the research status of domestic experts and scholars on it, based on the above; the future application of the recycled concrete in steel pipe is presented.

scholarly journals Experimental Study on the Mechanical Properties and Compression Size Effect of Recycled Aggregate Concrete

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2323
Author(s):  
Yubing Du ◽  
Zhiqing Zhao ◽  
Qiang Xiao ◽  
Feiting Shi ◽  
Jianming Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Size Effect ◽  
Compressive Stress ◽  
Failure Modes ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Substitution Ratio ◽  
The Impact

To explore the basic mechanical properties and size effects of recycled aggregate concrete (RAC) with different substitution ratios of coarse recycled concrete aggregates (CRCAs) to replace natural coarse aggregates (NCA), the failure modes and mechanical parameters of RAC under different loading conditions including compression, splitting tensile resistance and direct shear were compared and analyzed. The conclusions drawn are as follows: the failure mechanisms of concrete with different substitution ratios of CRCAs are similar; with the increase in substitution ratio, the peak compressive stress and peak tensile stress of RAC decrease gradually, the splitting limit displacement decreases, and the splitting tensile modulus slightly increases; with the increase in the concrete cube’s side length, the peak compressive stress of RAC declines gradually, but the integrity after compression is gradually improved; and the increase in the substitution ratio of the recycled aggregate reduces the impact of the size effect on the peak compressive stress of RAC. Furthermore, an influence equation of the coupling effect of the substitution ratio and size effect on the peak compressive stress of RAC was quantitatively established. The research results are of great significance for the engineering application of RAC and the strength selection of RAC structure design.

scholarly journals Discrete Element Simulation Analysis of Biaxial Mechanical Properties of Concrete with Large-Size Recycled Aggregate

2021 ◽  
Vol 13 (13) ◽  
pp. 7498
Author(s):  
Tan Li ◽  
Jianzhuang Xiao
Keyword(s):  
Mechanical Properties ◽  
Stress State ◽  
Strain Curve ◽  
Confining Pressure ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Aggregate Model ◽  
Large Size

Concrete made with large-size recycled aggregates is a new kind of recycled concrete, where the size of the recycled aggregate used is 25–80 mm, which is generally three times that of conventional aggregate. Thus, its composition and mechanical properties are different from that of conventional recycled concrete and can be applied in large-volume structures. In this study, recycled aggregate generated in two stages with randomly distributed gravels and mortar was used to replace the conventional recycled aggregate model, to observe the internal stress state and cracking of the large-size recycled aggregate. This paper also investigated the mechanical properties, such as the compressive strength, crack morphology, and stress–strain curve, of concrete with large-size recycled aggregates under different confining pressures and recycled aggregate incorporation ratios. Through this research, it was found that when compared with conventional concrete, under the confining pressure, the strength of large-size recycled aggregate concrete did not decrease significantly at the same stress state, moreover, the stiffness was increased. Confining pressure has a significant influence on the strength of large-size recycled aggregate cocrete.

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