Fly ash-based geopolymer concrete: study of slender reinforced columns

The objectives of this paper are to present the results of experimental study and analysis on the behaviour and the strength of reinforced geopolymer concrete slender columns. The experimental work involved testing of twelve columns under axial load and uniaxial bending in single curvature mode. The compressive strength of concrete for the first group of six columns was about 40 MPa, whereas concrete with a compressive strength of about 60 MPa was used in the other six columns. The other variables of the test program were longitudinal reinforcement ratio and load eccentricity. The test results gathered included the load carrying capacity, the load-deflection characteristics, and the failure modes of the columns. The analytical work involved the calculation of ultimate strength of test columns using the methods currently available in the literature. A simplified stability analysis is used to calculate the strength of columns. In addition, the design provisions contained in the Australian Standard AS3600 and the American Concrete Institute Building Code ACI318-02 are used to calculate the strength of geopolymer concrete columns. This paper demonstrates that the design provisions contained in the current standards and codes can be used to design reinforced fly ash-based geopolymer concrete columns. Introduction Concrete, an essential building material is widely used in the construction of infrastructures such as buildings, bridges, highways, dams, and many other facilities. One of the ingredients usually used as a binder in the manufacture of concrete is the Ordinary Portland Cement (OPC). The increasing worldwide production of OPC to meet infrastructure developments indicates that concrete will continue to be a chosen material of construction in the future [1]. However, it is well known that the production of OPC not only consumes significant amount of natural resources and energy but also releases substantial quantity of carbon dioxide (CO2) to the atmosphere [2]. Currently, the cement industries produce 1.5 billion tons of OPC each year. This adds about 1.5 billion tons of CO2 into the atmosphere [3, 4]. To address the aforementioned issues, it is essential to find alternative binders to make concrete. One of the efforts to produce more environmentally friendly concrete is to replace the amount of OPC in concrete with by-product materials such as fly ash [2]. An important achievement in this regard is the development of high volume fly ash (HVFA) concrete that utilizes up to 60 percent of fly ash, and yet possesses excellent mechanical properties with enhanced durability performance. Another effort to make environmentally friendly concrete is the development of inorganic aluminosilicate polymer, called Geopolymer, synthesized from materials of geological origin or by-product materials such as fly ash that are rich in silicon and aluminium [5]. According to Davidovits [6], geopolymerization is a geosynthesis that chemically integrates materials D. M. J. Sumajouw D. Hardjito S. E. Wallah B. V. Rangan (&) Curtin University of Technology, Perth, WA, Australia e-mail: V.Rangan@curtin.edu.au J Mater Sci (2007) 42:3124–3130 DOI 10.1007/s10853-006-0523-8