Microstructure, durability and mechanical properties of mortars prepared using ternary binders with addition of slag, fly ash and limestone

Nowadays, in order to reach a more sustainable cement industry, several strategies have been put into practice. One of them is to increase the use of eco-friendly cements with lower content of clinker, replacing it by additions. Among them, the characterization of the performance of mortars and concretes prepared using cements made with ternary binders, which incorporate two additions, are now an important field of study

In this research, the microstructure, durability-related properties and mechanical strength of mortars prepared using three ternary binders with incorporation of ground granulated blast furnace slag, fly ash and limestone have been studied. In these ternary binders, 30% of clinker has been replaced by two additions, and they consisted of 15% slag and 15% fly ash, 15% limestone and 15% fly ash, and 15% slag and 15% limestone, respectively. As reference mortars, it has also been prepared specimens with ordinary Portland cement without additions, as well as specimens made with other three binary binders, with only one of the studied additions, consisting of 30% limestone, 30% fly ash, and 30% ground granulated blast furnace slag, respectively. The mortars were exposed to an optimum laboratory condition (20ºC and 100% relative humidity) until 28 hardening days, when they were tested. The pore structure has been characterized using mercury intrusion porosimetry, electrical resistivity and differential thermal analysis. Absorption after immersion, ultrasonic pulse velocity and flexural and compressive strengths have also been studied. According to the results obtained, mortars with ternary binders showed an adequate performance.