Surface curing effects on reflection response of hardened cementitious mortar samples

Microwave non-destructive technique is one of the most popular method to determine materials features without any harm. Hence, this method is used to analyze the cementitious samples according to their water-to-binder (w/b) ratios. In this study, surface curing effect of hardened engineering cementitious mortar (ECM) cubic samples are analyzed based on their different w/b ratios (0.2 and 0.3) by comparing measured amplitude of reflection coefficient (|ℾ|) and conductance (g) of the ECM samples using open ended rectangular waveguide probe. Two dependencies of the samples are considered a) temporal dependencies, b) frequency dependencies. For both cases cubic samples are measured from top, lateral and bottom surfaces. To get the temporal dependencies, 1-9 and 720-815 curing days are taken into consideration at 4.56 GHz, while for the frequency dependencies, the frequency range is chosen between 3.95-5.85 GHz at 720th days of curing period. From this study it is noted that, crossover between conductance (g) values measured for bottom surfaces delays around 550 days, as opposed to measured values from top and lateral surfaces (for both 0.2 and 0.3 w/b ratios).