Improved Early-Age Cohesive Stress Response from Hybrid Blends of Micro and Macro Fibers

2021 ◽  
Vol 1046 ◽  
pp. 1-7
Author(s):  
Manjunath V. Bhogone ◽  
Kolluru V.L. Subramaniam

The fracture response of macro polypropylene fiber reinforced concrete (PPFRC) and hybrid blend of macro and micro polypropylene fiber reinforced concrete (HyFRC) are evaluated at 1, 3, 7 and 28 days. There is an improvement in the early-age fracture response of HyFRC compared to PPFRC. The changing cohesive stress-crack separation relationship produced by ageing of the concrete matrix is determined from the fracture test responses. An improved early-age cohesive stress response is obtained from the hybrid blend containing micro and macro fibers. The hybrid fiber blend also has a higher tensile strength at early age when compared to an identical volume fraction of macro polypropylene fibers.

2011 ◽  
Vol 219-220 ◽  
pp. 1601-1607 ◽  
Author(s):  
Tammam Merhej ◽  
Xin Kai Li ◽  
De Cheng Feng

This paper presents the experimental investigation carried out to study the behavior of polypropylene fiber reinforced concrete (PPFRC) under compression and flexure. Crimped polypropylene fibers and twisted polypropylene fiber were used with 0.0%, 0.2%, 0.4% and 0.6% volume fractions. The influence of the volume fraction of each shape of polypropylene fiber on the compressive strength and flexural strength is presented. Empirical equations to predict the effect of polypropylene fiber on compressive and flexural strength of concrete were proposed using linear regression analysis. An increase of 27% in flexural strength was obtained when 0.6% volume fraction of twisted polypropylene fiber was added. It was also found that the contribution of fiber in flexural strength is more effective when twisted fibers were used. The compressive strength was found to be less affected by polypropylene fiber addition.


2011 ◽  
Vol 261-263 ◽  
pp. 171-177
Author(s):  
Tammam Merhej ◽  
De Cheng Feng

An analytical model for compressive stress-strain curve of polypropylene fiber reinforced concrete (PPFRC) was proposed. The polypropylene fiber used was 60-mm long twisted fiber with aspect ratio of 120. The fiber was added in three volume fractions 0.2%, 0.4% and 0.6%. Tow concrete mixtures with varying water-cement ratio were used. The accuracy of the proposed model was evaluated by comparing the area under stress-strain curves for experimental and analytical model. The results showed good agreement between the experimental and analytical curves. In addition; empirical equations were proposed to quantify the effect of polypropylene fiber on compressive strength, strain at peak stress, and toughness of concrete in terms of fiber volume fraction.


2014 ◽  
Vol 584-586 ◽  
pp. 1355-1361 ◽  
Author(s):  
Liang Shan ◽  
Liang Zhang

The mechanical tests of normal concrete (NC) specimens, steel fiber reinforced concrete (SFRC) specimens and polypropylene fiber reinforced concrete (PPFRC) specimens have been carried out. Fiber-reinforced concretes containing different volume fraction and aspect ratio of steel and polypropylene fibers were compared in terms of compressive, splitting tensile, ultimate tensile properties. Test results indicate that the mechanical properties of NC can be improved by addition of steel fibers and can be enhanced with the increase of fiber content. However, polypropylene fiber may cause opposite effect, if volume fraction too high.


2014 ◽  
Vol 638-640 ◽  
pp. 1550-1555 ◽  
Author(s):  
Liang Shan ◽  
Liang Zhang ◽  
Li Hua Xu

The mechanical tests of hybrid steel-polypropylene fiber-reinforced concrete (HSPFRC) have been carried out. Concretes containing different volume fraction and aspect ratio of steel and polypropylene fibers mixed in one concrete grade were critically analyzed in terms of compressive, split tensile, axial tensile properties. Test results show that the fibers, when used in a hybrid form, can result in superior mechanical performance compared to their individual fiber-reinforced concretes.


2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Yu Qin ◽  
Hua Wu ◽  
Yong Zheng ◽  
Weina Wang ◽  
Zhijian Yi

Polypropylene fiber-reinforced concrete (PFRC) is a cement-based composite material with short-cut fibers which has been utilized to provide multidimensional reinforcement and enhance toughness of concrete. However, this improvement is closely related to the microstructural morphology of the concrete. A nondestructive technique using X-ray computed tomography (CT) was therefore used to grasp the microscopic texture of PFRC samples. The results showed that the orientation of microcracks, which appear in the interfacial transition zone, are along the surface of the coarse aggregate. The range of distribution of fibers is proportional to fiber volume fraction. The coarse aggregate influence distribution and orientation of polypropylene fibers whose shape are mainly fold line and curve. The dispersion of pores with small volume is uniform, and the distance between the pores with larger volume is short. The proportion of pores with the diameter in the range 0∼199 μm exceeds 70%, of which the sum of volume exceeds a half of total volume with the amount being about 1% of total amount.


2020 ◽  
Vol 12 (2) ◽  
pp. 549
Author(s):  
Chenfei Wang ◽  
Zixiong Guo ◽  
Ditao Niu

Polypropylene-fiber-reinforced concrete impacts the early shrinkage during the plastic stage of concrete, and the fiber volume content influences the durability-related properties of concrete. The purpose of this paper was to investigate the influence of fiber volume content on the mechanical properties, durability, and chloride ion penetration of polypropylene-fiber-reinforced concrete in a chloride environment. Tests were carried out on cubes and cylinders of polypropylene-fiber-reinforced concrete with polypropylene fiber contents ranging from 0% to 0.5%. Extensive data from flexural strength testing, dry–wet testing, deicer frost testing, and chloride penetration testing were recorded and analyzed. The test results show that the addition of the fiber improves the failure form of the concrete specimens, and 0.1% fiber content maximizes the compactness of the concrete. The flexural strength of specimen C2 with 0.1% fiber shows the highest strength obtained herein after freeze–thaw cycling, and the water absorption of specimen C2 is also the lowest after dry–wet cycling. The results also indicate that increasing the fiber volume content improves the freeze–thaw resistance of the concrete in a chloride environment. Chlorine ions migrate with the moisture during dry–wet and freeze–thaw cycling. The chlorine ion diffusion coefficient (Dcl) increases with increasing fiber content, except for that of specimen C2 in a chloride environment. The Dcl during freeze–thaw cycling is much higher than that during dry–wet cycling.


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