Novel fire-protecting mortars formulated with magnesium by-products

Several kinds of sprayable mortars are commonly used as passive fire protection of building structures. Several authors have reported the effect of different kinds of aggregates (e.g. vermiculite, fly ashes) in the thermal behaviour of fire-protecting mortars. In this study, the use of magnesium by-products as aggregates in fire-protecting mortars has been evaluated. These by-products were obtained during the calcination process of natural magnesite. Endothermic decompositions of the different aggregates have been determined and analysed by means of thermal techniques. Mortars with different mixtures of these by-products have been prepared. Mechanical properties and temperature behaviour tests have been performed to evaluate the suitability of these substances as aggregates in fire-protecting mortars. During the endothermic decomposition of the studied aggregates the advance of temperature inside the mortar is delayed. Mortar with a mixture of 50% of both magnesium by-products shows a good agreement between mechanical properties and temperature behaviour.