Title:
Flexural Residual Strength of Lightweight Concrete Reinforced with Micro-Steel Fibers
Author(s):
Hak-Young Kim, Keun-Hyeok Yang, Hye-Jin Lee, Seung-Jun Kwon, and Xiao-Yong Wang
Publication:
Materials Journal
Volume:
121
Issue:
1
Appears on pages(s):
93-104
Keywords:
crack mouth opening displacement (CMOD); fiber reinforcing index; lightweight aggregate concrete (LWAC); residual strength
DOI:
10.14359/51739203
Date:
1/1/2024
Abstract:
The objective of the present study is to assess the flexural residual
strengths of lightweight aggregate concrete (LWAC) reinforced
with micro-steel fibers. Further, the material class of such concrete
was examined through comparison with the fiber-reinforced
concrete classification specified in the provisions of fib 2010. Fourteen
beam specimens were classified into L (21 MPa [3.05 ksi]) and
H (40 MPa [5.80 ksi]) groups according to the design compressive
strength of LWAC. The volume fraction of micro-steel fibers
varied from 0 to 1.5% at a spacing of 0.25% in each beam group.
From the beam test results under the three-point loading condition,
flexural stress-crack mouth opening displacement (CMOD) curves
were measured and then discussed as a function of the fiber reinforcing index (βf). The flexural residual strengths corresponding
to four different CMOD values (0.5, 1.5, 2.5, and 3.5 mm [0.02,
0.06, 0.1, and 0.14 in.]) were compared with previous empirical
equations and fib 2010 classification. The various analyses of the
measured results indicate that βf can be regarded as a critical
factor in directly determining the magnitude of flexural residual
strengths and assessing material classification. The proposed
refined equations improve the accuracy in predicting the flexural
residual strengths of concrete beams with different densities and
reinforced with different types of steel fibers. Consequently, microsteel fibers are a promising partial replacement for conventional steel reinforcing bars to enhance the ductility of LWAC elements.