ASSESSMENT OF PERFORMANCE OF BIO SELF-HEALING MORTAR USING DIATOMACEOUS EARTH AND SILICA FUME

摘要

Cracking represents a major threat for the integrity and performance of structures. Self-healing concept was introduced to construction materials in order to enhance their performance and extend their service life with less repair. This study aims at assessing the performance of Portland cement mortar incorporating self-healing Bacillus Pseudofirmus bacteria using Diatomaceous earth (DE) to immobilize precursor and bacteria in mortar and lowering the pH level of mortar by using silica fume to provide a suitable growth environment for bacteria to generate limestone. The specimens were prepared at three different bacteria dosages and three DE dosages. Cracking of specimens was induced by load percent concept after 7 days and tests were performed at 14 and 28 days of curing. Micro analysis of the healed crack surface of the different specimens was performed and a parametric study was conducted to select the optimum dosage of bacteria, DE and mix design combination as well. The testing scheme for the mortar included sporulation tests over bacteria inside mortar specimens, compression test, chemical soundness test and ultrasonic pulse velocity. Results demonstrate that self-healing bacteria is promising technique in minimizing cracking. It is recommended to expand this work to cover more dosages of bacteria, different types of self-healing as well as concrete specimens.