Kamal Patel

MONITORING OF HYDRATION OF CEMENTITIOUS MATERIALS USING PZT PATCHES

"Strength monitoring of concrete using PZT patches In general, from the point of view of non-destructive evaluation (NDE), concrete technologists are interested in: (a) concrete strength determination, and (b) concrete damage detection. Special importance is attached to strength determination of concrete because its elastic behaviour and to some extent service behaviour can be predicted from its strength characteristics. Commonly used non-destructive strength estimation methods are the surface hardness method, the penetration technique, the pull-out test, the rebound hammer method, the resonant frequency method and the ultrasonic pulse velocity test (Malhotra1976, Bungey1982). These methods typically measure certain properties of concrete from which an estimate of its strength, durability and elastic parameters can be derived. Hence, they cannot be expected to yield absolute values of strength. The surface hardnessmethod, for example, is based on the principle that the strengthof concrete is proportional to its surface hardness. However,these strength prediction methods share many limitations. Forexample, the calibration charts of the surface hardness method,the rebound method and the penetration technique are validfor the particular type of the cement and aggregates used andthe age and moisture content of the specimen. In addition, theresults are not very reproducible. The penetration and the pull-outtechniques cause a small amount of damage to the concretesurface, which must be repaired. The resonant frequencymethod and the ultrasonic pulse velocity technique demandthat the transducers must be placed on the opposite faces ofthe component for accurate results. Very often, this is notpossible and thus limits the application of the two techniques. The electro-mechanical impedance (EMI) technique, onthe other hand, offers an interface between the global and thelocal techniques, thereby enabling a more cost-effective andhassle free alternative for both strength estimation and damagedetection of concrete structures. In the first step of project we are trying to monitor the hydration process of lime and want to differentiate, different type of chemical reaction which provide strength to lime. This part of the project is collaborated under the UKIERI and same work is going on in BATH university. After lime we will try to monitor the strength gain and curing process of concrete with the help of EMI technique which will help in strength determination damage detection and level of damage in concrete.