Investigation of Alkali silica reaction resistance of engineered cementitious composites

Concrete quality and durability are quite important factors in terms of completing the economic period of concrete structures. Concrete structure is exposed to many different effects in terms of durability during lifetime. One of these effects is the Alkali-silica reaction (ASR). ASR is a reaction between the reactive silica in the concrete aggregates (opal, chert, chalcedony and quartz) and the alkalis (sodium oxide and potassium oxide) in the pore solution of hydrated cement paste. This reaction negatively affects the durability and service life of the concrete. The reaction of the alkali-silica gel with moisture causes expansion of the gel. This expansion causes internal tensile stresses and causes cracks in the concrete. These cracks, which can be seen in the form of maps, cause a very negative situation in the strength of concrete. Engineering cementitious composites, simply named ECC in literature, have high ductility capacity with its micro mechanical design and exhibit multiple crack behavior. With the production of ECC, which show significant performance changes in both physical and chemical properties of concrete, it has been observed that the durability, ductility, toughness, etc. of concrete have improved. In this study, the effects of using reactive aggregates in fiber cement-based composites on ASR were investigated. According to the results, the fibre effect has decreased the expansion resulted from ASR by 15%. The highest tensile strength was observed in the air-curing, 90-day, 1st set, beadless control series (3.83 MPa) for basalt aggregate. The highest toughness value was observed in the air-curing, 28-day, 1st set, beadless blast furnace slag series for basalt aggregate (14.63 kj/m3).