Estimating coefficient of chloride extraction from concrete
Katedra Konstrukcji Budowlanych, Politechnika Śląska
The coefficient of chloride extraction from concrete was estimated for the purpose of this paper on the basis of variations in concentration of chloride ions in concrete. Electrochemical tests were conducted on extraction of chloride ions from ordinary concrete containing Portland cement CEM I 42.5 R. Those tests were used to determine concentrations of chloride ions in concrete exposed to chloride extraction at two different times. A change in time of concentration distribution of chloride ions over the thickness of concrete cover was used to estimate the coefficient of chloride ions extraction. Determined values of extraction coefficient were used to establish the duration of extraction sufficient for the complete removal of all chloride ions from concrete, which were responsible for corrosion of reinforcing steel.
Keywords: chloride extraction coefficient, distribution of chloride ions in concrete, effective extraction time
2019, Vol. 62, nr 12, pp.393-398
Destruction of acrylic coatings under the influence of climatic factors and environmental pollutants
Uniwersytet Technologiczno-Humanistyczny w Radomiu
The paper contains destruction assessment of acrylic coatings (of blue and red colour), aged under the influence of environmental factors for two years. The SEM investigations of coatings superficial layers (sublayers) documented a generation of different cracks kinds (including the silver cracks) as well as etchings in the shape of bands. The loss of aged coatings fragments from their superficial layers contributed to Ra and Rz roughness parameters increase which resulted in the coatings gloss decrease. Ageing changes, originating first in coatings superficial layers, contributed to their hydrophibility increase as the contact angle of the coatings wetting with water decreased with the ageing period increase. What more, the ageing caused a decrease of the coatings erosive resistance. The results of carried out investigations documented a higher resistance of the coatings containing the red pigment in the form of iron red to the influence of environmental factors including erosion (investigated in laboratory condition) compared with the coatings with the blue pigment in the form of cobalt phthalocyanine complex.
Keywords: acrylic coatings, environmental ageing, destruction, erosion
2019, Vol. 62, nr 12, pp.399-405