Title:
Durability Enhancement of Basalt Fiber-Reinforced Polymer-Seawater Sea-Sand Concrete Beam by Alkalinity Regulation
Author(s):
Shuaicheng Guo, Zhenqin Xu, and Deju Zhu
Publication:
Structural Journal
Volume:
121
Issue:
4
Appears on pages(s):
47-62
Keywords:
accelerated aging; basalt fiber-reinforced polymer (BFRP); beam; durability performance; flexural performance; low alkalinity; seawater sea-sand concrete (SSC)
DOI:
10.14359/51740569
Date:
7/1/2024
Abstract:
Reinforcing seawater sea-sand concrete (SSC) with basalt fiber reinforced polymer (BFRP) bars can adequately resolve chloride
corrosion issues. However, the multiple-element ions in seawater
and sea sand can increase the concrete alkalinity and accelerate
the degradation of BFRP bars. This study aims to enhance
the durability performance of BFRP-SSC beams by regulating
concrete alkalinity. A low-alkalinity SSC (L-SSC) is designed by
incorporating a high-volume content of fly ash and silica fume. A
total of 16 BFRP-SSC beams were designed based on the current
standards and prepared using normal SSC (N-SSC) and L-SSC.
The beam flexural performances before and after long-term exposure are characterized through the four-point bending test. The test results indicate that exposure in the simulated marine environment can reduce the load-bearing capacity and change the failure mode of BFRP beams with N-SSC. After exposure at 55°C for 4 months, the load-bearing capacity of the BFRP-SSC beams was reduced by 70.0%. Moreover, a slight enhancement of load-bearing capacity and ductility of the BFRP-L-SSC beams was observed due to the enhanced interface performance with further concrete curing.
Furthermore, the long-term performance of the sand-coated BFRP
bars is better than that of the BFRP bars with deep thread. The
load-bearing capacity of the BFRP-L-SSC beams increased by
approximately 20% after 4 months of accelerated aging due to
concrete strength growth, and the BFRP-L-SSC beams maintained
the concrete crushing failure mode after exposure. Finally, a loadbearing capacity calculation model for the BFRP-SSC beams is
proposed based on the experimental investigation, and its prediction
accuracy is higher than that of the current standards. This
study can serve as a valuable reference for applying BFRP-SSC
structures in the marine environment.