| Popis: |
This paper presents new materials obtained by alkaline activation, which generally have a lower environmental impact than that based on hydraulic binders. Calcareous filler was alkali activated by sodium hydroxide solutions in mortars prepared with siliceous sand. The chemical, physical and mechanical properties were studied after 28 days curing. XRD showed that setting and hardening processes of the binder result from the crystallization of sodium/calcium carbonate hydrate (pirssonite) and calcium hydroxide (portlandite). Depending on the formulation parameters,the compressive strength reached, after 28 days, 20 MPa [2900 psi] while flexural strength reached 4 MPa [600 psi]. A methodology, based on thermal analysis results, was applied to quantify the formed products and to evaluate the reagents consumption extent. Calculated amounts had a high reliability and corroborated the initial composition of the mortars. These results open interesting possibilities to improve the performances of these new type materials, based on alkali-activated calcareous filler. |
