Министерство высшего и среднего специального образования республики узбекистан ўзбекистон республикаси

 
Summary 
The measuring principle of photo-optical moisture sensors (LOF) sensors based on the moisture 
dependence of the light transparency of porous material, which are in contact with aqueous building 
material systems. With such LOF Sensors the setting and hardening and drying were examined after 
solidification (28d) and again water saturation in a calcium sulfate screed and cement mortar. Based 
on the normalized photo-diode voltages of fixed at defined locations in the building material samples 
LOF sensors were differences of behavior of the two material systems are established. In calcium 
sulfate screed (free, mobile, capillary-water) was observed as a result of the formation of gypsum 
(water retention) and the continuous drying of the screed for 11 days after a few hours of 
monotonically decreasing moisture content. From the information of an upper and a lower sensor in 
the floor could be closed to the capillary water transport. The drying process (water transport in the 
volume of the sample) was approximately 15 days after virtually complete. In contrast, at the cement 
mortar that after a w / c ratio-dependent time practically unchanged maximum moisture (with w / c = 
0.4 after 8 hours, at w / c = 0.7 after 40 hours ) a faster moisture waste (duration: 2 or 4 hours) occurs 
at minimal moisture contents. This rapid drop in moisture caused by CSH-phase formation and the 
consequent drastic water mobilization in the cement building material system. The comparison with 
gravimetric specific total moisture content is more than 7 days by means of the LOF sensors for the 
sample with w / c = 0.7 is always a higher content of mobile water. From the signal the LOF sensors 
an approximate ratio of the pore volumes of 2/1 (w / c ratio 0.7 / 0.4) can be derived for the samples 
with different w / c ratios. In both samples, the drying process (evaporation of mobile water) is not yet 
completed, indicated unanimously by both methods. The light-optical method allows specific insights 
into the setting reaction and microstructure formation in building material systems. 
The studies show for the use of LOF sensors in reorganization proceedings or Refurbishment valuable 
benefits of long temporal information on local moisture-dependent processes in the component. The 
light-optical methods also enables special insights into the setting reaction and microstructure 
formation in building material systems. In any event, the further development of the LOF sensors for 

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highly quantitative measurements is required, in particular the characterization of the moisture 
exchange processes between the porous sensor material and the surrounding moist building materials 
necessary (kinetics of equilibration).