Numerical study on fracture behavior of alkali activated concrete mixes for different beam sizes

Abstract

The present study considers the use of AAC mixes, since the raw materials that are being used to produce concrete are non-renewable natural resources, particularly Ordinary Portland Cement (OPC). Also, production of OPC contributes a greater amount of CO2 to the environment. Hence, an attempt has been made to study alternative construction materials keeping in mind sustainable development. The present numerical study compares the fracture behaviour and size effect of Alkali Activated Concrete (AAC) mixes with Ordinary Portland Cement Concrete (OPCC) mixes by numerically modelling the beams of AAC and OPCC using FEA software ABAQUS. Three different mixes of AAC, characterized by the variation of percentage volume of water-quenched slag (WQS) as a substitute for Natural sand (RS) and one OPCC mix, were studied. A three-point bending test was performed in ABAQUS for the beams of three different sizes, which are geometrically similar with constant thickness. Numerical simulation is performed under displacement control. Load versus CMOD graphs are plotted from the output data obtained from the numerical modelling. Fracture parameters such as Fracture energy (GF), Brittleness number (B), Characteristic length (lch), and Stress intensity factor (KIC) are then calculated from the obtained data and compared to understand the influence of fracture properties and size effect on the behaviour of structural elements since limited research works are available from the literature. From the results, it is observed that OPCC mixes show superior strength, high resistance to crack propagation, more toughness, and high fracture energy when compared to AAC mixes. AAC-50 concrete mix has shown better performance compared to the other two AAC mixes, i.e., AAC-0 and AAC-100. The results of this work can certainly be used to predict the non-linear behaviour of concrete and can be adopted in the design of structural elements.