The main purpose of the use of controlled permeability formwork (CPF) in concrete construction is to remove surplus mixing water and entrapped air from the fresh concrete and thereby enhance the properties of the concrete surface layer.
A number of OPC cement paste and concrete panels, with different mix proportions, were cast against CPF and impermeable form work (IF) and the profiles of total and capillary porosity, pore size distribution (PSD) and micro hardness of the cover have been established to assess the effectiveness of the CPF.
The use of CPF reduced the total and capillary porosity while increasing the micro hardness of the cement paste matrix and aggregate/cement paste matrix transition zone (TZ). The thickness of the CPF affected zone (CPFAZ) indicated by the micro hardness of the cement paste matrix appeared to be dependent upon the w/c ratio of concrete.