Discussion: Dynamic properties of large aggregate concrete under triaxial loading

This paper presents the results of an experimental study to investigate dynamic properties of polypropylene fiber-reinforced concrete beams with lightweight expanded shale (ES) and tire-derived aggregates (TDA). The mixture design followed past experiences in combining ES and TDA to enhance toughness and energy absorption in flexural behavior. The new mixture also contained 2% fiber by volume to improve such properties further. Experiments included compressive testing on cylindrical specimens as well as flexural testing on rectangular specimens to verify mechanical properties of fiber-reinforced tire-derived lightweight aggregate concrete (FRTDLWAC) subject to static loading. The results of these experiments confirmed reduction of mechanical strength due to addition of TDA and improvements in flexural strength due to fiber reinforcement. The dynamic testing included non-destructive impact loads applied to flexural specimens using a standard Schmidt hammer. A high-speed camera recorded the response of the system at 200 frames per second to allow detailed observations and measurements. Interpretation of energy-based dynamic results revealed that TDA enhances energy absorption through damping in flexural behavior. Results also indicated that fiber reinforcement reduces the amount of absorbed dynamic energy, even though; it enhances the absorbed strain energy due to crack bridging effect.

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Rigid Body Spring Model for Large Aggregate Concrete

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.179-180.79 ◽

2011 ◽

Vol 179-180 ◽

pp. 79-85

Author(s):

Huai Liang Wang

Keyword(s):

Stress State ◽

Rigid Body ◽

Element Model ◽

Failure Behavior ◽

Inhomogeneous System ◽

Spring Model ◽

Aggregate Model ◽

Large Aggregate ◽

Aggregate Concrete ◽

Random Aggregate

Based on the fundamental test data and the mesoscopic approach, a rigid body spring model is developed for simulation of the behavior of large aggregate concrete subjected to uniaxial or multiaxial load. Firstly, the concrete is treated as a three-phase inhomogeneous system; random aggregate model for fully-graded concrete is used to form the aggregate distribution. Then, based on the rigid body spring discrete element model, a procedure for mesoscopic study behaviour of large aggregate concrete under the two-dimensional stress state is given. At last, the comparison of numerical and experimental results shows that this method could effectively describe the failure behavior of large aggregate concrete under various plane stress state.

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Mechanical and Damping Properties of Recycled Aggregate Concrete Modified with Air-Entraining Agent and Polypropylene Fiber

Materials ◽

10.3390/ma13082004 ◽

2020 ◽

Vol 13 (8) ◽

pp. 2004 ◽

Cited By ~ 2

Author(s):

Chonggang Zhou ◽

Xingwang Pei ◽

Wenlong Li ◽

Yijun Liu

Keyword(s):

Mechanical Performance ◽

Dynamic Properties ◽

Damping Ratio ◽

Polypropylene Fiber ◽

Recycled Aggregate Concrete ◽

Recycled Aggregate ◽

Favorable Effect ◽

Damping Properties ◽

Aggregate Concrete ◽

Negative Effect

In this study, recycled aggregate concrete (RAC) modified with polypropylene fiber (PP) and air-entraining agent (AGA) was prepared, and the effects of PP and AGA on the static (compressive strength, Young’s modulus, and splitting tensile strength) and dynamic properties (dynamic modulus of elasticity and damping ratio) of RAC were investigated. The experimental results showed that the addition of an AGA and PP had a favorable effect on the damping ratio of the concrete, however, the addition of the AGA had a slightly negative effect on the mechanical performance of the concrete. The AGA and PP contents required to achieve the optimum damping ratio of the concrete with the least reduction in the mechanical performance were 0.02% and 0.10%, respectively. Furthermore, the addition of AGA was more effective than that of PP in improving the damping property of the concrete.

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