Rasheed, Mohammad Abdur and S, Suriya Prakash
(2018)
MECHANICAL CHARACTERISATION OF FIBER REINFORCED
CELLULAR LIGHTWEIGHT CONCRETE FOR STRUCTURAL
APPLICATION OF MASONRY.
PhD thesis, Indian institute of technology Hyderabad.
Full text not available from this repository.
(
Request a copy)
Abstract
Use of cellular lightweight concrete (CLC) in masonry construction has gained
tremendous popularity in recent decades owing to its sustainability, density, low
thermal conductivity and due to fewer mortar joints. Addition of fibers can improve
the ductile behavior of CLC under compression, shear, and tensile loadings. Data on
mechanical characterization of synthetic fiber reinforced CLC (FRCLC) is scarce. The
objective of this study is to develop a high-performance fiber-reinforced cellular
concrete to provide a better alternative to existing clay brick and aerated autoclaved
concrete blocks for structural applications of masonry. Use of micro-fibers (fibrillated)
enhances the pre-peak behavior of masonry by arresting cracks at micro-scale, while
macro (structural) fibers induce ductile behavior in the post-peak region by arresting
the crack propagation soon after the crack initiation. An extensive experimental
campaign has been carried out to mechanically characterize FRCLC under
compression, flexure, composite masonry prisms under compression, tension, fracture
and direct shear loading. Firstly, the mechanical behavior of CLC cylinders under pure
axial compression and CLC blocks under flexure is studied. After that, the behavior of
CLC masonry prisms under compression, dog-bone CLC specimen in tension, and
notched CLC blocks under flexure(fracture studies) were studied. Finally, the special
test setup was developed for testing the double-notched CLC specimen under direct
shear. Shear behavior of CLC with and without different fiber dosages was studied.
Test results indicate that the addition of structural fibers improves the compressive
strength and tensile strength by a factor of 2.0 and 3.4 respectively for 0.55% volume
fraction. Post-peak ductility improves up to a factor of 9 (for a strain limit of 0.01) in
case of compression and by multifold (for a strain limit of 0.06) in case of tension for
0.55% volume fraction. Similarly, it resulted in an increase of post-peak flexural
ductility for unnotched beams and fracture energy for notched beams by a factor of 15
and two respectively for a hybrid addition of 0.44% macro fiber and 0.02% microfiber
volume fraction. For composite masonry prisms, it increased up to 28.3% to 0.55%
when compared to that of control specimen. With further addition of micro-fibers of
0.02%, the compressive strength increased up to 45.2% for 0.44% dosage. Hybrid fiber
reinforcement enhanced the peak strength and ductility which indicates better crack
bridging both at the micro and macro levels. Semi-empirical models for characterizing
the stress-strain behavior of CLC under compression and tension is proposed. Also,
stress-strain curves for CLC masonry prisms are also developed. Digital image
correlation technique is used to monitor the crack growth process during the tension
test on the dog-bone specimen. The strains in the direction parallel to the direction of
loading obtained from DIC showed a close match with the strain obtained using
linearly varying displacement transducers. Acoustic emission technique is used while
characterizing the fracture and shear behavior. Charts for quantitatively assessing the
crack width were plotted using AE counts and energy. Three-dimensional source
location is attempted and the events located are classified into mode-I and mode-II. In
general, the fiber reinforced CLC developed in this study is shown to have adequate
mechanical properties for use in the structural application of masonry including load
bearing and infill construction.
Actions (login required)
 |
View Item |
Altmetric
Altmetric