Prediction of microcracks in concrete using fuzzy systems

Abstract

This paper presents a fuzzy based assessment system which estimates the diameter of micro cracks in concrete. The most important micro cracks in concrete are ITZ cracks. Interfacial Transition Zone (ITZ) in concrete involves an approximately 30μm zone around each aggregate, within which the porosity increases as the aggregate interface is approached. The ITZ micro cracking of concrete was investigated experimentally by means of compressive stress testing and microscopic analysis. For imaging the ITZ micro cracks, Secondary Electron signals of SEM have been used. To define the membership functions, large numbers of concrete specimens were made and their ITZ crack width was imaged and measured by SEM. W/C ratio, amount of nano-sio₂, micro sio₂ and age of specimens were considered as input membership functions and ITZ micro crack width was considered as output function. After the formation of black box and defuzzification, the system could predict the micro crack width correctly. Finally some random specimens were made to check the system prediction which showed suitable confirmation.