Experimental investigations on fibre reinforced geopolymer concrete as repair material for pavements

Abstract

Geopolymer is a relatively new construction material which could be produced by the chemical action between alumino-silicate material such as fly ash and alkaline solutions like sodium silicate or sodium hydroxide. Geopolymer concrete (GPC) reduces the CO₂ emission by 9 % compared to the concrete made with ordinary portland cement. Fibre reinforced geopolymer concrete (FRGPC) has already been used as a repair material for different construction purposes such as for tunnel linings and sewage pipes repairs due to its improved tensile characteristics and crack control properties. This study involves the experimental investigations on FRGPC as a repair material for rigid pavements. A mixture of sodium silicate and 8M sodium hydroxide solution is used as the alkaline activator to prepare the fly ash based geopolymer concrete. To increase the mechanical properties at ambient temperature calcium additives in the forms of calcium hydroxide and calcium oxide are added separately by replacing fly ash in the proportion 3%, 5% and 7% by weight of fly ash. Further to increase the low tensile strength of GPC, addition of polypropylene fibre in 0.2%, 0.4% and 0.6% by volume of concrete were also incorporated. The aspect ratio of the polypropylene fibres used is 300. The optimum values were determined based on the fresh concrete properties and mechanical properties. The results showed that the 7 day compressive and tensile strengths of FRGPC were increased by 36% and 14% respectively from fly ash GPC. The bond strength between the pavement substrate and the geopolymer repair material is also studied. The bond strength of the fibre reinforced repair material is found to be more than the permissible values as per relevant codes of practice. Abrasion resistance of the repair material is also tested as a measure of durability aspects to check the suitability for usage on rigid pavements.

Keywords—Geopolymer Concrete, Alumino-Silicate, Rigid pavements, Substrate, Alkaline solution, Repair material