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Experiment on Early Horizontal Shrinkage of Fiber Reinforced Concrete Based on Negative Capillary Pressure Theory(PDF)

《建筑科学与工程学报》[ISSN:1673-2049/CN:61-1442/TU]

Issue:
2020年03期
Page:
73-80
Research Field:
Publishing date:

Info

Title:
Experiment on Early Horizontal Shrinkage of Fiber Reinforced Concrete Based on Negative Capillary Pressure Theory
Author(s):
HE Hua-nan;  DAI Xiang-yang
(State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, Liaoning, China)
Keywords:
fiber reinforced concrete;  air-entry value;  early horizontal shrinkage;  negative capillary pressure theory;  laser ranging;  local cracking
PACS:
TU528.572
DOI:
10.19815/j.jace.2019.01012
Abstract:
In order to research the influences of different parameters of polypropylene fiber on early stage horizontal shrinkage of concrete, based on negative capillary pressure theory, the horizontal shrinkage tests were carried out. The developments of both negative capillary pressure and electric resistance in the early stage of concrete were measured by water potential tensiometer as well as multimeter respectively, and the whole process curve of the development of negative capillary pressure and electric resistance in the early stage of concrete was obtained. By combining the development curves of negative capillary pressure and electric resistance, the air-entry value Paev of negative capillary pressure was obtained. Meanwhile, the relationship between different parameters of polypropylene fiber and Paev was discussed and a comprehensive formula to express the relationship between parameter G and Paev was given. Parameter G synthesized fiber volume fraction and fiber length and Paev. In addition, the development process of early horizontal shrinkage deformation of concrete was tested by high-precision laser displacement sensor. The results show that the adding of polypropylene fiber into concrete can effectively slow down the early development rate of negative capillary pressure in concrete and significantly reduce the limit value of negative capillary pressure, thereby inhibiting the early horizontal shrinkage deformation of concrete. Meanwhile, the Paev value of negative capillary pressure in the early stage of concrete is increased, which improves the early cracking resistance strength of concrete. When the fiver volume fraction is 0.1% and the fiber length is 18 mm, the Paev value of the negative capillary pressure of the concrete reaches 41.1 kPa, which has the strongest early resistance to local cracking of concrete. At the same time, the early horizontal shrinkage deformation of concrete is well controlled, and the maximum horizontal shrinkage is 72.6% lower than that of plain concrete.

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Last Update: 2020-06-08