Moisture from concrete has been estimated to be responsible for over $1 billion annually from damages in floor coverings. To prevent damages, flooring manufacturers require installers to test concrete moisture levels to determine if the concrete has dried sufficiently to receive flooring or covering. Two of the main tests used in the United States to determine concrete moisture levels are moisture vapor emissions rate (MVER) tests and relative humidity (RH) tests. Changes in ambient temperature can affect the results of both RH and MVER tests. The goal of this study was to investigate the effects of ambient temperature changes on the RH of concrete, and compare the sensitivity of RH measurements to the results of MVER tests at the same ambient temperature. The RH of concrete was measured at 20%, 40%, 60%, and 80% of depth in each sample and tracked over a period of 24 days to develop drying curves at each depth, and drying profiles of each sample. The changes in concrete RH due to a change in ambient temperature were predicted using the psychrometric process and a model developed during this study. Due to size constraints on the concrete samples, ASTM 1869 had to be altered during the MVER tests. Typical RH change in the concrete samples was under 4% RH after either an increase or decrease in an ambient temperature of 5.5°C (10°F). The psychrometric process predicted that the concrete RH would change between 20% - 40% RH after the ambient temperature changed by 5.5°C. Psychrometric properties were not able to full describe the behavior of air in concrete pores so a new model was created to better predict the change in concrete RH after a change in ambient temperature. The developed model was able to predict concrete RH change within 5% error over the range of tested temperatures. / Master of Science

Tvenkinių šlaitų tvirtinimo plokščių (toliau – ŠTP) būklę bei ilgaamžiškumą lemia jas veikiantys poveikiai ir apkrovos, susidarantys dėl agresyvios aplinkos, klimato poveikio bei kitų veiksnių. Vienas iš žalingų reiškinių – dėl prastos šlaitų priežiūros išaugę drėgmę mėgstantys krūmai (pvz. karklai) ar net medžiai, kurių šaknys ieškodamos drėgmės, iškilnoja ir suskaldo šlaitų tvirtinimo plokštes. Darbo tikslas – įvertinti krūmų ir medžių šaknų ardomojo poveikio reikšmę Lietuvos tvenkinių šlaitų tvirtinimo gelžbetoninių plokščių būklei. Šiam tikslui pasiekti buvo atlikta literatūros analize, įvertinant tvenkinių šlaitų tvirtinimo plokštes veikiančius veiksnius ir apkrovas. 2008 – 2009 m. mokslinių ekspedicijų metu natūriniais tyrimais įvertinta 16 tvenkinių šlaitų tvirtinimo gelžbetoninių plokščių būklė pagal STR.1.12.03:2006. Remiantis natūrinių tyrimų rezultatų analize detalesniam tyrimui parinktos Antanavo hidroelektrinės žemutinio bjefo gelžbetoninės plokštės, kurių suardymo pobūdis leidžia teigti, kad šlaitų tvirtinimo plokštės buvo suardytos veikiant medžio šaknims. / Durability and technical state of reinforced concrete slabs for ponds slope protection depends on the maintenance circumstances – aggressive environmental impacts, loads from climate, etc. One of the harmful phenomenons are moisture–loving shrubs (for example, wicker), which appeared because of the bad slope maintenance or even trees, the roots of which heave and shatter (when searching for moisture) slabs for slope protection. The aim of the work was to evaluate the destructive force of the trees and shrubs roots on the reinforced concrete slabs for slope protection. For the achievement of this goal the literature analysis was carried out in order to determine factors and loads effecting slabs for slope protection. During the scientific expeditions in 2008–2009 the condition state of the reinforced concrete slope protection slabs of 16 ponds were evaluated by field investigations according to STR. 1.12.03:2006. Following the analysis of the results of field investigations the reinforced concrete slabs from the lower pond of the Antanavas hydroelectric power station were chosen for the more detailed investigation. The destructive character of these slabs allows stating that slope protection slabs were destructed because of the trees roots.