scholarly journals Flexural Behavior of Composite Concrete Slabs Made with Steel and Polypropylene Fibers Reinforced Concrete in the Compression Zone

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3616 ◽  
Author(s):  
Barbara Sadowska-Buraczewska ◽  
Małgorzata Szafraniec ◽  
Danuta Barnat-Hunek ◽  
Grzegorz Łagód

The paper presented aimed at examining the effect of a fiber-reinforced concrete layer in the compressed zone on the mechanical properties of composite fiber-reinforced concrete slabs. Steel fibers (SF) and polypropylene fibers (PP) in the amount of 1% in relation to the weight of the concrete mix were used as reinforcement fibers. The mixture compositions were developed for the reference concrete, steel fiber concrete and polypropylene fiber concrete. The mechanical properties of the concrete obtained from the designed mixes such as compressive strength, bending strength, modulus of elasticity and frost resistance were tested. The main research elements, i.e., slabs with a reinforced compression zone in the form of a 30 mm layer of concrete with PP or SF were made and tested. The results obtained were compared with a plate made without a strengthening layer. The bending resistance, load capacity and deflection tests were performed on the slabs. A scheme of crack development during the test and a numerical model for the slab element were also devised. The study showed that the composite slabs with fiber-reinforced concrete with PP in the upper layer achieved 12% higher load capacity, with respect to the reference slabs.

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Radim Čajka ◽  
Zuzana Marcalíková

Abstract The presented article deals with experimental testing of fiber-reinforced concrete slabs using a specialized testing device, the so-called Stand. The experimental testing involved a total of three slabs with different fiber dosing. Dosing was chosen of 25, 50, and 75 kg/m3. In the case of fiber dosing of 75 kg/m3, the concrete recipe was changed with regard of fiber dosing. The test equipment allows vertical loading of the elements and, together with the installed track sensors and computer technology, records the vertical deformations. The deformation of the slabs was evaluated using 2D deformation sections in the slabs of mounted sensors and using 3D deformation sections with the use of interpolation of intermediate values. The article is supplemented by a test evaluation of the mechanical properties. These were concrete compressive strength, modulus of elasticity, and tensile strength. The mechanical properties were also tested and evaluated for plain concrete (dosage 0 kg/m3). By evaluating the mechanical properties and deformations, it is possible to observe differences in the behavior of fiber-reinforced concrete elements for different degrees of fiber reinforcement. The article evaluates the positive effect of fibers on the load capacity and the deformations of slabs.


2014 ◽  
Vol 662 ◽  
pp. 24-28 ◽  
Author(s):  
Xi Du ◽  
You Liang Chen ◽  
Yu Chen Li ◽  
Da Xiang Nie ◽  
Ji Huang

With cooling tests on polypropylene fiber reinforced concrete and plain concrete that were initially subjected to different heating temperatures, the change of mechanical properties including mass loss, uniaxial compressive strength and microstructure were analyzed. The results show that the compressive strength of concrete tend to decrease with an increase in temperature. After experiencing high temperatures, the internal fibers of the polypropylene fiber reinforced concrete melted and left a large number of voids in it, thereby deteriorating the mechanical properties of concrete.


2021 ◽  
Vol 11 (17) ◽  
pp. 7926
Author(s):  
Qian Zhang ◽  
Wenqing Zhang ◽  
Yu Fang ◽  
Yongjie Xu ◽  
Xianwen Huang

In order to solve the problem of highly brittle shaft lining under dynamic loading, a combination of hybrid fiber concrete mixed with steel and polypropylene fiber is proposed to make shaft lining. C60, the concrete commonly used in shaft lining, was selected as the reference group. The static mechanical properties, dynamic mechanical properties, and crack failure characteristics of the hybrid fiber concrete were experimentally studied. The test results showed that compared to the reference group concrete, the compressive strength of the hybrid fiber-reinforced concrete did not significantly increase, but the splitting tensile strength increased by 60.4%. The split Hopkinson compression bar results showed that the optimal group peak stress and peak strain of the hybrid fiber concrete increased by 58.2% and 79.2%, respectively, and the dynamic toughness increased by 68.1%. The strain distribution before visible cracks was analyzed by the DIC technology. The results showed that the strain dispersion phenomenon of the fiber-reinforced concrete specimen was stronger than that of the reference group concrete. By comparing the crack failure forms of the specimens, it was found that compared to the reference group concrete, the fiber-reinforced concrete specimens showed the characteristics of continuous and slow ductile failure. The above results suggest that HFRC has significantly high dynamic splitting tensile strength and compressive deformation capacity, as well as a certain anti-disturbance effect. It is an excellent construction material for deep mines under complex working conditions.


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