Ranking of suitable concrete mix parameter based on splitting tensile strength of partially set concrete subjected to delays in casting using Multi-criteria decision making approach

Abstract

Delays in casting of freshly prepared concrete mix is always uncertain and cannot be predicted in the initial time. The interval of time t between the preparation of dry mix including the water addition i.e. t = 0 and casting of the same concrete where required at some elapsed time t is called as time lag. In this paper, attempt is made to correlate the experimental splitting tensile strength variation of partially set concrete (PSC) with the analytical model developed earlier for selfing and the correlation factors are estimated. Also as the success of any task is always contingent on the ability to make decisions and recognize to select the best feasible option from a variety of options. Therefore a multi criteria decision making (MCDM) tool is implemented for ascertaining the suitable concrete mix of PSC. Three different types of concrete mix were tried and compared to the normal mix to check the variation in splitting strength. The experimental and analytical values of tensile strength are validated and the average correlation factor is observed 0.998. Furthermore, using the Analytical Hierarchy Process (AHP) for ranking, normal PSC (Type-1) and PSC with 1% synthetic fibers (Type-4) showed maximum splitting tensile strength at 75 minutes time lag, whereas PSC with 20% fly ash (Type-2) and PSC with 25% fly ash (Type-3) showed maximum splitting tensile strength at 100 minutes time lag, indicating that the addition of fly ash retarded setting time and kept PSC more workable.The AHP model also suggested 1% synthetic fibers (Type-4) as the most suitable concrete mix parameter among four alternatives experimented.