Durability of limestone mortars based on quaternary binders subjected to sulfuric acid using drying–immersion cycles

• The quaternary binders has a positive effect vis-a-vis the durability of limestone mortars.
• The limestone filler, blast furnace slag and natural pozzolana in limestone mortars has a benefic effect.
• The performances of the limestone mortars with additions are better than that of the control mortar in sulfuric acid.
• The weight loss, strength loss and pH are the quantification parameters of durability.
• Seven drying–immersion and heating–cooling cycles accelerate the attack of mortars.

The aim of this work is to produce limestone mortars with blended-cement by substituting partially the clinker by three mineral additions. Namely; the limestone filler, the blast furnace slag and the natural pozzolana combined simultaneously to the cement for rates of 30%, 10% and 10% by turn. The mortar specimens were immersed in sulfuric acid solutions, and subjected to two protocols of attack. The first is slow; it is a continuous immersion. Specimens are exposed to 3% solution of sulfuric acid at 23 ± 1 °C. The second protocol is accelerated, and consists to subject the mortar samples to 7 drying–immersion and heating–cooling cycles, followed by a continuous immersion up to 180 days. The drying is done at 60 °C and the exposure in lime water and 5% sulfuric acid solution at 23 ± 1 °C. In this study the quantification parameters of durability of mortars are the weight loss and the compressive strength loss. The follow-up (the monitoring) of pH of the exposure solutions was carried out until end of the tests. The synergistic action of the quaternary binders has a positive effect vis-a-vis the durability of limestone mortars immersed in sulfuric acid solution and the performances of the limestone mortars with quaternary binders are better than that of the control mortar.