First Experiences with Geopolymeric Mortars of Alkaline Activation Based on Natural Pozzolans

Abstract

The geopolymers are a new class of inorganic polymers that are obtained from the alkaline activation of natural minerals or industrial wastes and by-products. In the present investigation we describe the destructive and non-destructive tests carried out on the mortars made from the alkaline activation of the natural pozzolans from the Las Carolinas deposit to measure mechanical and durability properties. For this purpose, sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) were used as alkaline agents. The results were analyzed through an experimental methodology where variables such as alkaline solution and curing time were determined. Finally, the mortars were analyzed mechanically, where their compressive strength was determined at 7 and 28 days of age, and their durability was also evaluated from the measurements of electrical resistivity and ultrasonic pulse velocity. The results obtained were compared with the values specified by the Cuban standard regarding the properties of mortars, also revealed that the pozzolanic material used as source of pure aluminosilicate has low alumina content, which affects the low mechanical resistance of the mortars The final product presents a series of properties that demonstrate the potential of natural pozzolans as a cementing material, which does not have any type of industrial process, or additives, or CO2 emissions during its use, the main reason for this research.