Assessing effects of chloride-induced corrosion of galvanized reinforcing steel in cement mortar, using impedance spectroscopy and scanning microscopy
Wydział Budownictwa, Politechnika Śląska
Wydział Inżynierii Lądowej, Politechnika Krakowska
Comparative tests on corrosion of galvanized reinforcing steel in specimens from cement mortar were performed. Ribbed steel of grade B500SP, one of the most commonly used in reinforced concrete structures in Poland, was analysed and hot dip galvanized. Calcium chloride added to batched water, turned out to be a corrosion inducing agent. Specimens without chlorides were used as the reference elements. Corrosion risk of reinforcing steel in the mortar was evaluating using Electrochemical Impedance Spectroscopy (EIS) and Linear Polarization Resistance (LPR) techniques. Corrosion effects on galvanized reinforcement in the cement mortar were observed and analysed under the scanning microscope.
Keywords: concrete structures, reinforcing steel, corrosion, chlorides, zinc coating, EIS, LPR, scanning microscopy.
2018, Vol. 61, nr 7, 176-181
Control of cement mortars shrinkage modified by lime and shrinkage reducing admixture
Instytut Badawczy Dróg i Mostów
Lime has been traditionally used material for the production of masonry mortars and plasterworks. The effect of the lime addition onto shrinkage of standard mortars is presented in the paper. The shrinkage of tested mortars was determined by Graff-Kaufmann method and the modern method so called the gutters shrinkage method. The analysis of the possibility of mortars shrinkage reducing by the use of admixtures is also presented in the article. The following admixtures were chosen for tests: a typical shrinkage reducing admixture based on polypropylene glycol (SRA) and an expansive one based on calcium oxide (EXP).
Keywords: mortars, lime, shrinkage reducer, shrinkage
2018, Vol. 61, nr 7, 182-185
Research of diffusive dissolution phenomena of reactive steels in zinc bath with bismuth addition
FAM S.A., ul. Avicenny 16, 54-611 Wrocław
Politechnika Śląska, Wydział Inżynierii Materiałowej i Metalurgii, Krasińskiego 8, 40-019 Katowice
During hot-dip galvanizing process a bismuth is often applied as alloy addition to zinc bath. This element effects on stabilization of forming process of protective coating on steel and it improves surface properties of coating. The results of investigation of dissolution phenomena of silicon- containing reactive steels in zinc bath with 0,5% bismuth addition have been presented. Due to using the model conditions it is possible to analyse a diffusive dissolution process on the basis metal-zinc bath interface and it determines a bismuth role. The diffusion coefficient of iron dependent on its concentration in liquid zinc has been determined by the Boltzman-Matano method in the temperature of 450°C. Bismuth addition to the zinc bath produces more than twice decrease of dissolution rate of reactive steels. Diffusion rate decreases, that is best visible for Sandelin’s steel with critical silicon addition 0.05%, especially in ζ-phase range in diffusion layer of the coating.
Keywords: hot dip galvanizing, zinc coating, dissolution, diffusion, reactive steel.
2018, Vol. 61, nr 7, 186-190
CORROSION PROTECTION IN PRACTICE
Steel structure corrosion prevention in power industry – further considerations
Biuro Techniczne BT, Racibórz
Politechnika Śląska, Katowice
The problem described in the paper is related to protective coatings applied onto prefabricated elements for power plant. The authors emphasise that despite outspreading knowledge, the quality of work is not always satisfying. Specification is quite often the source of error, because its statements tend to be unreliably written.
Keywords: steel structure, power plant, corrosion protection, protective coatings
2018, Vol. 61, nr 7, 192-193