Bonicelli A.,Polytechnic of Milan |
Crispino M.,Polytechnic of Milan |
Giustozzi F.,Polytechnic of Milan |
Shink M.,CTG Italcementi Group
Advanced Materials Research | Year: 2013
Pervious concrete is a relatively new material, standards and rigorous specifications for construction and placement are therefore still missing. One the one hand, the main characteristic to achieve is a high permeability to allow meteoric water percolate in the pavement and evaporate from the subgrade. On the other hand, developing pavement cementitious mixtures able to retain high void contents and reach significant mechanical performance entails an in-depth analysis of materials and construction practices. Pervious concrete can indeed be placed using a standard paver as for asphalt mixtures but the compaction stage is usually demanded to the contractor practices: light steel hand-rollers or standard drum rollers are both used without an in-depth knowledge of compaction properties of the cementitious mixture. The present paper aims at investigating the influence of compaction methods on the mechanical performance and void contents of pervious concrete mixtures. Several compaction procedures were tested modifying the compaction energy and the mixture characteristics while preserving high permeability. The main objective was to simulate and identify the effect of commonly adopted in situ compaction techniques - i.e.: tamper compaction as provided by the paver, steel hand-roller compaction, or standard drum roller compaction. Results showed how the compaction energy, water/cement ratios, and the percentage of cement affect the Indirect Tensile Strength and void contents of the mixtures. Further investigations were also conducted in order to comprehensively evaluate how the variation in the percentage of cement and water/cement ratio influenced the stiffness of the material. © (2013) Trans Tech Publications, Switzerland.
Romano M.C.,Polytechnic of Milan |
Spinelli M.,Polytechnic of Milan |
Campanari S.,Polytechnic of Milan |
Consonni S.,Polytechnic of Milan |
And 3 more authors.
Energy Procedia | Year: 2013
Calcium looping appears as one of the most promising technologies for CO2 capture in short-medium term plants featuring the combustion of fossil fuels. Ca-looping (CaL) is a regenerative process which takes advantage of the capacity of Calcium Oxide-based sorbents in capturing the CO2 from combustion gases by means of sequential carbonation-calcination cycles. CaL technology appears very promising for CO2 capture from cement plants, since the CaO-rich purge stream which must be extracted from the process can be a valuable raw material for clinker production. The aim of this study is to investigate from the technical and economic side the benefits arising from the integration between a coal-fired power plant with CaL process for CO 2 capture and a cement plant using the CaL purge to substitute part of the raw meal. The main parameters affecting the CaL process are varied and the effects on both the plant performance and the final cost of clinker and electricityare discussed.
Mainini A.G.,Polytechnic of Milan |
Poli T.,Polytechnic of Milan |
Zinzi M.,ENEA |
Cangiano S.,CTG Italcementi Group
Energy Procedia | Year: 2012
This paper presents an approach to measure, characterize and simulate photometric performances of light transmission efficiency of an innovative transparent concrete panel for façades. The transparency was obtained by a texture of PMMA resin insertions in the fiber reinforced concrete panel. In the first part of the paper integrating sphere measurements were collected to derive spectral optical properties of the panel. The optical properties of a specimen were measured for incidence angles between normal and 60° and the spectral results were reported. The data collected during the measures were used to: create and validate a simplified Radiance model of the panel and to optimize simulation parameters to estimate properly the total internal reflections effects thought the PMMA resin insertions. © 2012 The Authors.
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.
Fan W.,CNRS Chemistry Laboratory |
Fan W.,CTG Italcementi Group |
Stoffelbach F.,CNRS Chemistry Laboratory |
Rieger J.,CNRS Chemistry Laboratory |
And 4 more authors.
Cement and Concrete Research | Year: 2012
It is well-established that a competitive adsorption exists between polycarboxylate superplasticizers (SP) and sulfate ions solubilized in the interstitial solution of cement paste, which may cause a loss of the dispersing properties. This has been explained by competitive weak ionic interactions between functional carboxyl groups and sulfate ions with cement grains. In this study, SPs including trialkoxysilane functional groups have been synthesized. Adsorption and dispersing properties of these SPs were evaluated in the presence of different concentrations of Na 2SO 4 added in aqueous solution. It appeared that a partial substitution of carboxyl groups by trialkoxysilane in the polymer makes them more resistant to sulfate ions. We suggested that the high adsorption capacity of these SPs results from the formation of strong bonds between hydroxysilane groups and calcium silicate hydrate phases. The improved compatibility of these new silylated SPs has been demonstrated through the formulation of two different concrete equivalent mortars. © 2011 Elsevier Ltd. All rights reserved.
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.
Le Coustumer P.,University of Bordeaux 1 |
Amin F.,CTG Italcementi Group
35th International Conference on Cement Microscopy 2013 | Year: 2013
Identifying heterogeneities within a clinker and understanding the processes leading to these changes are of major importance for cement makers. Indeed, the great diversity of the fuels used makes it usual to face microscopic particles whose mineralogical, chemical or structural properties are different from the matrix. Currently, the characterization of these phases is mainly based on optical microscopy, scanning electron microscopy, X-ray diffraction and electron microprobe analysis. The main advantages of these methods are theirs simplicity, the sample preparation (simple and normalized) and theirs scales which are micrometric, On the other hand the main limit, in relation with trace element distribution into the cement, clinker and mortar is the scale because trace element or minor phases act at nanometric level (concentration are lower than the percent, size of the potential neophases induced by the process and their distribution which has to be précised). For this reasons additional techniques have to be faced like HRTEM/X-EDS or GDOES. They have been tested on the clinkers analysis, burned with alternative fuels, and on mortar doped with nanometric Ti02. These methods can be named micropetrographics should be able to precise the distribution of such trace elements like phosphorus or Ti, nature of the neo phases potentially generated into the manufactured products. A basic question quite difficult to answer is: are they trapped into the exiting phases without structural modifications or do they precipitated by creating new nanophases? Such question is of a great importance as soon as in the first case (trapping mechanism) long term durability is supposed to be not modified. In the second case (precipitation), how these news nanophases can act at long term on the durability or ageing or chemical reactions?
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.
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.
Vola G.,CTG Italcementi Group |
Marchi M.,CTG Italcementi Group
Periodico di Mineralogia | Year: 2010
The Luserna Stone (Pietra di Luserna) is a leucogranitic orthogneiss, characterized by a micro-Augen texture, with a marked foliation that is mostly associated to a visible lineation: it geologically pertains to the Dora-Maira Massif, and outcrops in a quite large area (approximately 50 km2) of the Cottian Alps, on the border between the Turin and Cuneo provinces (Piemonte, Italy). In this study five samples of granulated rock (1-2 mm) are considered, from three different localities; they are representativeof three facies (Massive, Splittable and Bianchetta). The mineralogical and petrographic features of this stone, used for many centuries as building material, have been characterised by complementary methods, such as: 1) Quantitative Phase Analysis (QPA) by the Rietveld method using X-ray powder diffraction data (XRPD); 2) mineral modal analysis using optical microscopy (OM) on thin-sections by point-counting a statistical number of grains; 3) scanning electron microscopy equipped with an energy-dispersive spectrometer (SEM-EDS); 4) X-Ray fluorescence spectroscopy (XRF). The proportion of minerals in each sample determined by XEPD and OM are in good agreement between them. The SEM-EDS data combined withmineral proportions determined by XRPD and OM allow to determine bulk chemical compositions of these five samples very close to those obtained by XRF. The decreasing of alkali content determines a linear increase of phyllosilicate and a decreasing of feldspar amounts. These results evidence that complementary methods can efficiently be used to evaluateundesired constituents in aggregate for concrete, such as phyllosilicates (i.e. micas andchlorites). The combination of XRF and XRPD data allows an accurate and rapid compositional and mineralogical evaluation of the different facies of the Luserna stone.