Author(s)
Muhammad Nasir Amin, Muhammad Armaghan Siffat,Khan Shahzada and Kaffayatullah Khan
Abstract
This study investigates the effectiveness of an agricultural by-product wheat straw ash (WSA) as an internal curing agent in reducing the autogenous shrinkage of high-performance concrete (HPC).
After incineration under different controlled time–temperature conditions, grinding and sieving were performed to obtain two different grades of fine WSA (F-WSA) and superfine WSA (SF-WSA).
Subsequently, material characterization tests were carried out, followed by tests for mechanical properties and autogenous shrinkage potential of concrete incorporating 10% and 20% F-WSA and SF-WSA as a partial replacement of cement.
The results demonstrated slightly higher compressive and tensile strength of concrete containing SF-WSA compared to control, whereas concrete with F-WSA demonstrated comparable strength results to that of the control concrete.
Moreover, a significant reduction in 7 days’ autogenous shrinkage was observed in concrete containing 10% and 20% F-WSA by 42% and 25% compared to that of control concrete, respectively. This reduction in autogenous shrinkage increased further to 57% and 40% for concrete with 10% and 20% SF-WSA, respectively.
The results of microstructural investigations on paste samples such as FTIR, TGA, and N2 adsorption analyses revealed a more refined and compact microstructure of paste samples with increasing fineness of WSA due to the formation of a more densified C-S-H phase.
The improvement of the microstructure is attributable to the improved pozzolanic properties of SF-WSA compared with F-WSA.
Keywords
wheat straw ash; high-performance concrete; compressive and tensile strength; autogenous shrinkage; thermogravimetric analysis; Fourier transform infrared spectroscopy analysis; nitrogen adsorption
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