EFFECT OF MOISTURE CONTENT OF CONCRETE SUBSTRATE ON WRINKLING OF COVERING FLOOR BY DRAGGING LOAD

A moisture content of concrete substrate is one of important factors of durability floor performance. It is known experientially, that an amount of moisture causes lower bonding between concrete substrate and covering floor and makes some problems. Unfortunately, the quantitative measurement studies of the relationship are not enough. And it has not defined a moisture content index based on scientific evidence to prevent durability floor performance problems. In this study, we declared a quantitative relationship between the moisture content of concrete substrate and wrinkling shape of the covering floors generated by dragging load. As the sample of dragging load, we are focusing on a behavior of an electric bed with locking casters in hospitals. Wrinkling caused by the electric bed is effected by characteristics of covering materials and an amount of moisture of concrete substrate. Under our premises, using some kinds of covering materials, we investigated the relationship between moisture content and wrinkling shape by the dragging load. At first, concrete substrates pasted polyvinyl chloride sheets were constructed as test-samples for experiments. The concrete substrates are defined 5 levels about “moisture content grades” by Japan Research Conference of Floor Construction Technology. The moisture content of the concrete substrates was managed using high frequency capacitance moisture meter. And, some floor coverings were pasted on these substrates. They were chosen that 5 combinations of the floor coverings and adhesives which are frequently used in hospitals. 25 samples were experimented to generate the wrinkling using an experimental device. This device can reproduce the dragging load on covering floors by moving test samples with applying vertical load through a locked caster. We investigated the results of the experiment focusing on height of the wrinkling. The results of this study are as follows. 1) Moisture content of substrate took effect deeply in wrinkling by dragging load. Decreasing moisture content was prone to be lower the wrinkling height. Therefore, sufficient drying process of substrate was effective against wrinkling height of covering floors. 2) We investigated the relationship between the moisture content and a height of wrinkling in each moisture levels in base case of “Grade I” which is the driest state. As a result, the wrinkling height is approximately equal to the height in “Grade I” when substrate dried until “Grade IIa”. Ther