Effect of fly ash on mechanical and durability properties of mortar containing microfibers with different length.

Cement was replaced by fly ash to improve the mechanical properties of the mortars, and microfiber was added to the mixtures to improve the durability properties of the mortars. This study also investigated the effect of microfibers on the durability index values of cement mortars with fly ash content. In the preparation of the samples, CEM I 42.5 R-type cement, standard sand and fly ash (FA) were used as raw materials. Three different sizes of polyamide micro-synthetic fiber were added to mixtures. 0.5% (by mass) fiber was added to mixtures. Physical properties were determined according to Archimedes' principle after 28 and 90 days of curing. Then, compressive and flexural strength tests were performed. In conclusion, strength increased with an increase in curing time, and ≥30% FA addition increased water absorption, resulting in a decrease in mechanical strength. FA addition up to 20% improved the 90-day specimens'strength. The 28-day specimens no R1228 (46.4 MPa) and 90-day specimens no 2FA1290 (49.1 MPa) had the highest compressive strength. According to the durability index, FA replacement improved durability. Although the results varied according to fiber lengths, it was concluded that the use of 12 mm fiber was more suitable in terms of durability. [ABSTRACT FROM AUTHOR]