Influence of TiO2 and Fly ash on Fracture Parameters of Concrete Notched Beams

Abstract

This paper explains the experimental research on fracture properties of concrete using TiO2 nano powder (NT) (1, 2, 3, 4%) and fly ash (FA) (10, 20, 30, 40%). Three point bend tests were conducted on 153 notched beams in a closed loop servo control machine with crack mouth opening displacement (CMOD) control and opening rate of 0.0005 mm/s. A total 17 mixes were prepared with combination NT+ FA with the above percentages. Work of fracture method (WFM) and size effect method (SEM) was used to analyze fracture parameters. The results for WFM and SEM show that fracture energy, fracture toughness and brittleness number increase with increase in NT and FA percentages, while the characteristic length decreases. In each mix varying from NT1FA10 to NT4FA40, the fracture energy increased by 20.92% and fracture toughness increased by 34.61%. The mix with 4% NT showed significant improvement of 38.46% for fracture toughness and 20.93% for fracture energy. The mix indicating brittle behavior as the characteristic length (Lch ) decreases with increase in percentage of NT and FA and the length of fracture process zone (CF ) decreases with increase in percentage of NT and FA which indicates the brittle behavior of material.