MOISTURE CONTENT AND POROSITY OF SUBSTRATE CONCRETE FLOOR SLABS FOR FINISHING MATERIALS

Abstract

Pore structure and moisture content of concrete slabs with different water-cement ratio and drying conditions were studied to find the appropriate curing conditions for floor finishings. Decrease of moisture content of concrete within 2.5 cm from the drying surface was conspicuous and a portion 0.5 cm below the surface reached 2.5% within 14 days whereas a portion deeper than 7.5 cm was almost unchanged after the self desication was matured. The densification of pore structure owing to the hydration of cement was possible when a finishing was applied at the age of 1 day, whereas no densification was observed leaving coarse pores due to an insufficient hydration when a finishing was applied after 3 days. In order to solve an incompatibility for a concrete slab to assure sufficient hydration for strength and durability and sufficient drying as a substratum of finishings, it is recommended to have a moist curing for 7 days after placing followed by a drying.