Thermal decomposition of the CaO in traditional lime kilns. Applications in cultural heritage conservation

•The calcination process of the limestones depends of the porosity and crystalline structure original of the limestones.•The calcination temperatures, longer residence time and CO2 and steam pressure affects the size and porosity of the CaO crystals.•The quicklimes calcined in traditional kilns are characterized by greater particle and pore size.•The quicklimes with greater volume of pores, the lime slaking reaction is less exothermic.•The size of the particles CaO affects the rate of the lime slaking reaction.