Fracture and impact properties of short discrete jute fibre-reinforced cementitious composites

Abstract

This paper conducted research on fracture and impact properties of short discrete jute fibre reinforced cementitious composites (JFRCC) with various matrix for developing low-cost natural fibre reinforced concretes and mortars for construction. Fracture properties of JFRCC were tested on notched concrete beams at 7, 14 and 28 days and the results were interpreted by the two-parameter fracture model (TPFM). Impact resistance of JFRCC were examined on mortar panels with the dimensions of 200×200×20 mm3 at 7, 14 and 28 days through repeated dropping weight test. Qualitative and quantitative analyses were conducted for crack pattern, impact resistance and energy absorbed by JFRCC mortar panels based on eye observations and measurement from an oscilloscope. In addition, compressive, flexural and splitting tensile strengths of JFRCCs were tested at 7, 14 and 28 days conforming to relevant EN standards. It was found that, by combining GGBS with PC as matrix, JFRCC achieved higher compressive strength, tensile strength, fracture toughness, critical strain energy release rate, and critical stress intensity factor than those with combination of PFA and PC as matrix. Impact tests, however, indicated that JFRCC mortar panels with PFA/PC matrix possessed higher impact resistance, absorbed more impact energy and survived more impact blows upon failure than those with GGBS/PC matrix at the ages of 14 and 28 days. JFRCC mortar panels did not shatter into pieces and demonstrated a ductile failure while the plain mortar ones behaved very brittle and shattered into pieces. Upon impact failure, fibre pull-out was observed in JFRCC mortar panels with PFA/PC matrix while fibre fracture in those with GGBS/PC matrix. Besides, the impact resistance, in terms of the number of impact blows survived and the total energy absorbed upon failure, of JFRCC mortar panels decreased with age.