Argille calcinate ad attivazione alcalina per lo sviluppo di nuovi leganti idraulici a basso impatto ambientale

Cement is the most widely produced material around the world. Developing countries are facing a growth of population that required an increase of infrastructures. Due to this situation, the cement industry needs to find the best compromise between increasing the cement production and reducing the associated CO2 emission. A promising solution has been found in the use of alkali-activated binders. These materials offer technical properties comparable to those of Portland cement, but with a much lower CO2 footprint. The aim of this project is the synthesis of alkali-activated binders from calcined clays (kaolin and smectite) activated with an 8M NaOH solution and cured at room temperature. The effect of the addition of calcite and various additives is investigated. All the specimens studied in this thesis were characterized by different techniques, including X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and compressive strength tests. The data show that the compressive strength is higher for the samples treated at 750 °C. For what concern the natural row materials, smectite shows higher compressive strength. The addition of 30% calcite in all specimens increases the compressive strength, possibly due to the interaction with the alkaline activator, leading to the formation of a more compact and stiff matrix.