Abstract
In this study, a series stainless steel mesh/Cr p reinforced geopolymer composites with different Si/Al molar ratio ( N ) were designed and prepared, where N = 1.75, 2 and 2.25, respectively. The effect of Si/Al molar ratio in the geopolymer matrix on mechanical properties and fracture behavior of the geopolymer composites were investigated. The microstructure of geopolymer became more compact when Si/Al increased from 1.75 to 2, which was beneficial to the improvement of geopolymer’s mechanical properties. And continuing to rise to 2.25 for Si/Al, the completely curing of geopolymer composites required more time compared with lower Si/Al, which can be attributed to the different microstructure and chemical composition caused by the different Si/Al. The optimum Si/Al molar ratio was about 2 at which the composites samples present the best mechanical properties with the flexure strength of 115.3 MPa and elastic modulus of 11.0 GPa, respectively. The results of fracture behavior suggested that geopolymer composites with N is 2.25 displayed the behavior characteristics of metal materials, which can be attributed to a poor integrated condition in interface between reinforcements and geopolymer matrix.
Highlights
While traditional design and evaluation approaches are based on the principle of maximizing the economic efficiency and include quality, cost, and time, the new approach of ‘sustainable construction’ emphasizes the importance of reducing the environmental impact of buildings and infra-structures [1]
All the samples show typical amorphous character, i.e., a broad amorphous hump at ~28o 2θ [20], which suggested that the different Si/Al ratio did not changed the nature of the geopolymer matrix
The results of X-ray diffractometer (XRD) indicated that the stainless steel mesh and chromium powder were not involved in the reaction with geopolymer matrix [21]
Summary
While traditional design and evaluation approaches are based on the principle of maximizing the economic efficiency and include quality, cost, and time, the new approach of ‘sustainable construction’ emphasizes the importance of reducing the environmental impact of buildings and infra-structures [1]. Geopolymer can provide comparable performance to traditional cementitious binders in a range of applications, but with the added advantage of significantly reduced greenhouse emissions [2-7]. Geopolymers are a class of cementitious aluminosilicate binder materials synthesized by a geopolymerization reaction between alumino-silicate oxides and alkali-metal silicate solutions under alkaline conditions, with partially or fully amorphous polymeric structures containing tetrahedral SiO4 and AlO4 randomly distributed along the polymeric chains [8-11]. The structure and mechanical properties of geopolymers are affected by several parameters such as chemical composition and reactivity of the raw materials, nature and concentration of the activating solution, curing conditions. Apart from the ideal ratio, some losses may occur in the mechanical properties of the material due to the change of the geopolymer structure [19]
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