Effect of Elevated Temperature on Some Properties of Polypropylene Fiber Reinforced Khorasan Mortar

Abstract

In many parts of the world, it is known that lime-based mortars and plasters are used in buildings that have the characteristics of historical monuments. On the other hand, Khorasan mortar is a traditional type of lime-based mortar that is frequently found in historical buildings that constitute the important cultural heritage of our country. Khorasan mortar was used as a masonry mortar and plaster during the construction of structures for centuries. It is also frequently preferred in the restoration works of these structures. For this reason, studies are continuing to improve the strength and durability properties of this mortar. In this study, the effect of polypropylene fiber reinforcement on some properties of Khorasan mortar specimens exposed to high temperatures was investigated. For this purpose, in addition to the control mixture, four different mortar mixtures containing 3 mm long polypropylene fiber at 0.4, 0.6 and 0.8% ratios were prepared. Water/binder, aggregate/binder ratios and target flow value for all mixtures were constant at 0.91, 3.0 and 150±10 mm, respectively. 80% of the binder mass consists of natural hydraulic lime and 20% of brick dust in all mixtures. 70% crushed brick and 30% river sand were used as aggregate. At the end of the 90-day curing period, the unit weight, ultrasonic pulse velocity and modulus of dynamic elasticity values of the mortar specimens were determined in their initial state and after exposure to 300, 600, 900 ˚C. As a result of the experimental study, it was determined that the need for water-reducing admixture increased to reach the target flow value with the increase in fiber utilization ratio in mortar mixtures. In addition, depending on the fiber utilization ratio, it was observed that the values in question decreased in the initial state and after exposure to a temperature of 300 ˚C. At higher temperatures, fibrous and non-fibrous specimens were found to have similar properties in terms of ultrasonic pulse velocity and modulus of dynamic elasticity.