Desenvolvimento de agente biológico para autocicatrização em matrizes cimentícias

Abstract

The objective of this work was to evaluate Pythium spp. as a self-healing agent in cementitious matrices since it is composed of cellulose and that these attract Ca2+ which favor the formation of CaCO3, in addition, it would also act as a reinforcement. CaCl2 was used to attenuate nutrient potato and dextrose (BD) inhibition. Pythium has to develop in media with CaCl2 and alkaline pH, as the matrix has pH>10. 100% (24g/L) BD concentration was adopted, which is indicated. To evaluate self-healing, Pythium was inoculated into cracks in mortar test specimens (CP) (w/c 0.3), made using a metal saw (0.3 mm) after 14 days, visualized at 3, 7, 28 and 56 days after agent inoculation. CP were also produced with 1% polypropylene fibers, cracked in a flexion test and area recovery (RA), water absorption (AA), load recovery (RC), SEM and EDS tests were performed in 7, 28 and 56 days. Identification by PCR (polymerase chain reaction) determined the species Pythium aphanidermatum. Regarding CaCl2, at 7 days, the 0% and 25% treatments were statistically the same. At 14 days, it was constant up to 150%. The biological agent has developed to pH10. The BD 24g/L inhibition curve showed that it is inappropriate in cementitious matrix. The BD 6g/L inhibition index obtained Low Inhibition at 150%, 175% and 200%. The appropriate recommended medium was 6g/L of BD with 150% CaCl2. DTG confirmed that Pythium is basically cellulose. The sealing starts in 3 days and evolves completely up to 56 days. With 105% CR, 98,43% RA and AA reduction. SEM and EDS showed carbonate hyphae and crystals of carbonates, aluminates and C-S-H in the fissured region. All these factors show Pythium aphanidermatum. promising as a self-healing agent.