Identification of microplane coefficients to reproduce the behaviour of ultrafine blast-furnace slag binder grout samples

Description

Ultra-fine blast-furnace slag binders have recently been introduced to repair masonry. The reduced particle diameter of these binders makes them especially suitable for use as grouts, since this characteristic enables these grouts to fill even the smallest voids. The current necessity and effectiveness of Finite Element Analysis in any process concerning construction, repair or reinforcement of building structures remains unquestionable. In this way, the calibration of Finite Element material models for their correct performance has become compulsory. Regarding quasi-brittle materials, such as mortar and grouts, the Microplane model is recommended to reproduce their behaviour. This paper is targeted towards obtaining Microplane model coefficients to exactly reproduce the behaviour of ultrafine blast-furnace slag grout samples. To this end, several compressive tests have been carried on in order to obtain the experimental stress–strain curves that define the behaviour of these samples. Furthermore, reverse engineering by means of an optimisation algorithm successfully attained the possible coefficients to reproduce this material with the Microplane model. The correctness of these coefficients has been verified with a new campaign composed of compressive tests, Double Punch tests, and flexural tests. These tests have been reproduced by Finite Element Analysis, thereby confirming the accuracy of the set of coefficients. Thus, two are the main conclusions obtained: (1) the framework for the modelling of ultra-fine blast-furnace slag grout elements based-on the Microplane model has been proposed, implemented and validated; and (2) a value for the coefficients of the abovementioned model has been proposed.

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