Fiber Reinforced Cement Mortars Degradation after their Exposure to Fire Conditions

Cement based mortars reinforced by glass and polypropylene fibres were exposed to fire conditions up to 900 °C from 10 min to 2 hours and after their slow cooling, were tested under compression and bending loadings. We can see that three distinct stages are appeared. At first, up to 300°C, a not absolutely specified behaviour is appeared. Reinforced mortar’s mechanical response is depended on temperature level, time duration and type of cement composite. So, its strength can be slightly increased, remains unaltered or can be even reduced. At the following stage from 300°C up to 800°C, a gradual general degradation is appeared. Mortar’s strength and rigidity are rapidly reduced so low, reaching approximately the 10% of their initial values. At the same time yielding strain is increased, leading to an almost constant toughness. The whole degradation of cement composite is completed at the third stage where a total destruction is appeared. At the temperature level of 900°C and above the aggregates decomposition is recorded, giving an grained like material