Physico-chemical and microstructural fire-induced alterations into metakaolin-based vegetable and polypropylene fibred mortars

Sustainable development today requires smart deployment of renewable environmentally-friendly materials and innovative thoughts. It is unavoidable to assess their performance and engineering properties to be accepted by the civil engineering community. Thus, vegetable fibers as reinforcement for cementitious materials are a very interesting eco-option for the construction industry. This paper study the behavior of metakaolin cementitious mortars reinforced with vegetable (VF)/polypropylene (PP) fibers under high temperature exposure. Vegetable fibers were previously treated with calcium hydroxide in order to improve their paste-adhesion and durability. Four VF mortars (including Alfa mortar (MAF), Diss mortar (MDS), Date Palm mortar (MDP), Hemp mortar (MHE)), one PP mortar (MPP) and one control mortar (CM) were made. The mixes had a sand/binder ratio of 3, 30% matakaolin content, and 0.1%/m(3) fibers dosage. The induced firing-changes were studied at room temperature (20 degrees C) and after heating process at 150, 300, 450, and 600 degrees C. The tested properties were: residual mechanical strengths, ultrasonic velocity, thermal conductivity, porosity, density, thermogravemetric analysis, and optical and microstructural observations. The results showed a similar behavior of vegetable and polypropylene fibers' mortars under fire with a different mechanism; a diminished spalling with fibred mortars; Ca(OH)(2) treatment and metakaolin rich matrix was a good prescription to get enhanced VF-mortars properties. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The study investigates the behavior of metakaolin cementitious mortars reinforced with vegetable/polypropylene fibers under high temperature exposure, showing similar performance between vegetable and polypropylene fiber mortars under fire with different mechanisms, reduced spalling with fiber mortars, and enhanced properties of vegetal fiber mortars through treatment with calcium hydroxide and a metakaolin-rich matrix.