Effect of quaternary cementitious systems containing limestone, blast furnace slag and natural pozzolan on mechanical behavior of limestone mortars

• Mineral additions have a benefic effect vis-a-vis to the mechanical properties of mortars.
• Simultaneous incorporation of BFS, NP and LF reduces the compromising effect of this one.
• Mechanical, thermal and chemical methods are the methods for activate BFS and NP.
• Activation of LF, BFS and NP affected the mechanical properties of hardened mortars.

This paper describes an experimental research on the study of mechanical behavior of crushed limestone mortars of the Algerian Central Saharan Atlas made from a mixture of three mineral additions. Namely; Portland cement, limestone filler, blast furnace slag and natural pozzolan which were simultaneously used to obtain blended cements that contain 50% mineral additions. Mortars have been the subject of a series of normative tests, in order to achieve a characterization, more or less detailed, which allows assessing the quality of these mortars in terms of standards. Three methods for activation of pozzolanic reactivity of BFS and NP were used, namely; mechanical, thermal and chemical methods to activate the pozzolanic reaction of slag and pozzolan at an early age.Three activation methods of pozzolanic reactivity of mineral admixtures were used. Mineral additions were activated mechanically by grinding to 3800 cm2/g, and 6000 cm2/g Blaine surface area (mechanical method), elevated temperature by curing mortar specimens at 8 °C, 20 °C and 40 °C (thermal method), and chemically by mixing the mixture with 1% of alkaline activator (NaOH) based on the mass of binder (chemical method).Tests were carried out to characterize the mechanical behavior of binary, ternary and quaternary binders of hardened limestone mortars at 2, 7, 28, 90, 180 and 365 days. Test results showed that the simultaneous incorporation of LF, BFS and NP in partial replacement to the OPC where the role of the mechanical, thermal and chemical activation of these mineral additions slightly affected the mechanical properties of hardened mortars based on crushed limestone sand at short and long terms (from 2 days to 90 days).