MECHANICAL CHARACTERISATION OF FIBER REINFORCED CELLULAR LIGHTWEIGHT CONCRETE FOR STRUCTURAL APPLICATION OF MASONRY

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.

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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.

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IITH Creators:
IITH CreatorsORCiD
S, Suriya Prakashhttp://orcid.org/0000-0003-0319-1773
Item Type: Thesis (PhD)
Subjects: Civil Engineering
Divisions: Department of Civil Engineering
Depositing User: Team Library
Date Deposited: 01 Aug 2018 04:23
Last Modified: 01 Aug 2018 04:23
URI: http://raiith.iith.ac.in/id/eprint/4341
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