Enea D.,University of Palermo |
Guerrini G.L.,CTG Italcementi Group
Transportation Research Record | Year: 2010
Innovative cement-based premix products for surface coating of buildings that possess photocatalytic activity arouse great interest because of the results they can achieve in reducting air pollution and maintaining aesthetics. This photoactivity is induced by a photocatalyst, titanium dioxide, that can accelerate the oxidation processes of air pollutants, particularly nitrogen oxides and volatile organic compounds, which aremainly produced by incomplete combustion of fuel and are present in urban environments through the exhaust gases of motor vehicles. Surfaces that are coated with these products acquire a self-cleaning characteristic (maintenance of original color) because the decomposition of organic compounds significantly reduces the ability of atmospheric particles to adhere to treated surfaces, thus facilitating their removal and ensuring a more durable color. These products are particularly suited for use in highly congested areas (i.e., historical centers of cities, tunnels, roads), where air pollution reaches significant levels. This study describes the photocatalytic performances of a series of premix products containing mineral pigments. The tested products are based on hydraulic binders (natural hydraulic lime and cement), and the pigments are inorganic. A wide range of colors was chosen, and the performances of base products were investigated to provide a wider choice to the designers. After a brief introduction of the principles of photocatalysis, the results of a wide experimental work are described. Some consideration of methods of curing and natural exposure is also reported.
Princigallo A.,CTG Italcementi Group
Materiales de Construccion | Year: 2012
A method was developed to measure the diffusion coefficient of chloride ions in cement paste based on an analytical solution to Fick's 2nd law in a cylindrical coordinate system. This natural method yielded diffusivity results within as little as a month. Testing time was reduced by exploiting the three-dimensional inward flux in the specimen. In an attempt to determine the saturation concentration, dense portland cement pastes were exposed to a concentrated chloride solution. The method proved to be useful for exploring cement hydration-induced changes in the diffusion coefficient of cement paste.
Folli A.,University of Aberdeen |
Pade C.,DTI |
Hansen T.B.,Aalborg Portland A S |
De Marco T.,CTG Italcementi Group |
MacPhee D.E.,University of Aberdeen
Cement and Concrete Research | Year: 2012
The present work offers a general overview about application of titanium dioxide (or titania), TiO2, photocatalysis to concrete technology in relation to enhanced aesthetic durability and depollution properties achieved by implementing TiO2 into cement. Chemistry of degradation of Rhodamine B (RhB), a red dye used to assess self-cleaning performances of concretes containing TiO2, as well as oxidation of nitrogen oxides (NOx), gaseous atmospheric pollutants responsible for acid rains and photochemical smog, is investigated using two commercial titania samples in cement and mortar specimens: a microsized, m-TiO2 (average particle size 153.7 nm ± 48.1 nm) and a nanosized, n-TiO2 (average particle size 18.4 nm ± 5.0 nm). Experimental data on photocatalytic performances measured for the two samples are discussed in relation to photocatalyst properties and influence of the chemical environment of cement on titania particles. Impacts on applications in construction concrete are also discussed. © 2011 Elsevier Ltd. All rights reserved.
Pasquino R.,Materials and Industrial Production |
Nicodemi F.,Materials and Industrial Production |
Vanzanella V.,Materials and Industrial Production |
Alfani R.,CTG Italcementi Group |
Grizzuti N.,Materials and Industrial Production
Rheologica Acta | Year: 2013
A detailed rheological study of aqueous solutions of methylhydroxyethylcellulose has been carried out in the presence of different acrylate-based graft polymer used as additive contents. Both polymer components are used in cement formulations to improve the flow performances of the concretes, but no physicochemical studies can be easily found in the literature. The content of the graft polymer has been varied between 0.1 and 2.7 wt% in an aqueous solution with a fixed content of 6.5 wt% of methylhydroxyethylcellulose. Creep curves were performed at different stresses in order to build up the flow curves for the various solutions. We found that the addition of the graft polymer triggers a phase transition, which is made more dramatic by the presence of an external flow. A "flow-phase diagram" has been obtained, which could be used as a guide for determining the critical conditions for the onset of the flow-induced instability. © 2013 Springer-Verlag Berlin Heidelberg.
Vola G.,CTG Italcementi Group |
Gotti E.,CTG Italcementi Group |
Brandon C.,Pringle Brandon Architects |
Oleson J.P.,University of Victoria |
Hohlfelder R.L.,University of Colorado at Boulder
Periodico di Mineralogia | Year: 2011
This study reports chemical, mineralogical and petrographic characterization of ancient hydraulic concretes from the Roman piers at Santa Liberata Orbetello (Grosseto) Italy (∼ 50 B.C.), and breakwaters at the harbour of Caesarea Palestinae, Israel (c. 25 B.C.), drilled by the ROMACONS (Roman Maritime Concrete Study) team in 2003-2005. Both sets of concrete contain a pozzolanic sanidine-and clinopiroxene-bearing tuff, identified as coming from the pyroclastic deposits of the Phlegrean Fields (Naples), the so-called pulvis Puteolanus of Vitruvius. However, the content of tuff changes, being predominant at Santa Liberata, whereas it is only a smaller fraction of the total aggregate at Caesarea that is mostly composed of local kurkar calcareous sandstone, with occasional ceramic fragments. The cementitious binding matrix presents amorphous gel-like, silica-rich C-A-S-H, with subordinated "sparry" calcite cement, and unusual dull white grains composed of calcite, tobermorite, and ettringite, apparently derived from reaction with hydrated lime in seawater. Saline encrustations, from the diffusion of chlorides and sulphates, and characteristic authigenic spherical zeolites with the "rosette" texture also occur within the mortar's porosity. These new data put further constraints on the various reactions occurring in roman concretes in over two thousand years of curing in an aggressive marine environment.