848 research outputs found
Atmospheric deterioration of cement plaster in a building exposed to a urban environment
No full textThe work presents results achieved in a research study on the effects of atmospheric deposition on the cement mortar of the basement in a twentieth-century building located in the city of Ancona (Italy). The degree of damage as a function of the sampling depth is evaluated by combining visual observation, scanning electron microscopy, X-ray diffraction, ion chromatography, differential and gravimetric thermal analysis and the quantitative determination of elemental carbon. Sulphation is found to be the main damage mechanism occurring on the cement mortar constituting the base section of a building since the concentration of sulphate increases from the inner to the outer layer at the expense of the carbonate. The absence of sulphite indicates a direct formation of sulphate, possibly due to the catalytic effect of heavy metals present in the carbonaceous particles of the black crust. Insoluble sulphates, such as ettringite, do not form at the surface, but within a deeper layer of the basement due to its instability to atmospheric carbon dioxide. © 2008 Elsevier Masson SAS. All rights reserved
Economic sustainability of a social farm with young autistic people
No full textYoung people with autism who finish the training school, in most case, cannot count on support or projects for their integration into the world of work, because it is believed that autism involves the inability to develop skills. But until now, the social projects for autism have focused mainly on young people of school age so that you do not have a clear perception of the disease in adulthood.
The inclusion of adolescents with autism in social farms has achieved excellent results and this, in recent years, has led to the development of experimental projects to promote job placement for autistic adults in the agricultural sector. The development of relational and organizational skills by adolescents with autism included in social farms, has matured the idea that these people may be able to work producing goods and services with economic goals. Agricultural work seems to be the best one to help autistic people to break down the wall of isolation.
In this context, through a case study of Umbria and the experience gained in other Italian regions, the paper analyzes the conditions necessary to achieve economic sustainability of a social farm for young people with autism. The objective is to contribute to plan a social farm that is also an economic model of reference for other similar experiences. For this purpose we use the tools of solidarity economy going beyond the horticultural therapy, or hippotherapy, which are disciplines widely used in therapeutic protocols.
The issues analyzed concern the following contexts: organizational (skills acquisition, distribution of roles, creation of mixed groups), productive (choice of production methods, range of goods and services offered), commercial (selling arrangements based on the values of relationship lasting and continuous), relational and institutional (interaction with the local population, public awareness on the value of production, expansion of constructive cooperation on the association ANGSA Umbria).
Finally, some reflections are conducted on the need to integrate the various policies in view of the new programming on Rural Development 2014-2020, which could seriously contribute to the sustainable inclusion into the world of agricultural work of young autistic people
Calcium sulfoaluminate cement and fly ash-based geopolymer as sustainable binders for mortars
No full textThis work investigates the hydration behaviour and the physico-mechanical properties of mortars based on calcium sulfoaluminate (CSA) cements and fly ash-based geopolymers (GEO) as alternatives to ordinary Portland cement. According to the EN 1504-3, mortars were prepared in order to reach three compressive strength classes, namely R1, R2 and R3 (R1 with Rc ≥ 10 MPa, R2 with Rc ≥ 15 MPa and R3 with Rc ≥ 25 MPa). CSA mortars were prepared by using sulfoaluminate cement alone (R3) or in mixture with a limestone filler (R1 and R2); GEO mortars were manufactured by alkali-activation of coal fly ash and calcium aluminate cement with a sodium silicate and potassium hydroxide water solution. The hydration behaviour was evaluated on pastes submitted to differential thermal-thermogravimetric and X-ray diffraction analyses. Mortars was analysed through mercury intrusion porosimetry; their mechanical properties were evaluated in terms of compressive strength and dynamic modulus of elasticity. Furthermore, capillary water absorption and drying shrinkage tests were carried out in order to evaluate their durability. Due to the rapid ettringite formation, CSA-based mixtures reached their maximum compressive strength values faster than the corresponding GEO mortars. Results showed that the lower modulus of elasticity of GEO mortars causes the higher drying shrinkage. Moreover, the lower porosity exhibited by GEO mortars was responsible for the lower water capillary absorption
Calcium sulfoaluminate and alkali-activated fly ash cements as alternative to Portland cement: study on chemical, physical-mechanical, and durability properties of mortars with the same strength class
No full textThere is an increasing interest towards the development of alternative binders for the manufacture of sustainable mortars and concretes. Ordinary Portland cement (OPC) is the most commonly used material in construction, even if its production process is highly polluting. Both calcium sulfoaluminate (CSA) and alkali-activated cements (AAC) are potential alternative binders to be used in both structural (R3 class, with Rc " 25 MPa) and non-structural applications (R1 and R2 classes, with Rc " 10 MPa and Rc " 15 MPa, respectively) according to UNI EN 1504-3. This paper reports the hydration mechanisms and the evolution of porosity of OPC-, CSA- and AAC-based binders. The properties of fresh and hardened mortars, belonging to the above-mentioned mechanical strength classes, were evaluated and compared with particular emphasis on durability properties in terms of capillary water absorption, drying shrinkage, and resistance to sulfate attack. The results show that CSA-based mortars exhibit the lowest drying shrinkage due to their highest elasticity modulus. AAC mortars are characterized by the highest water vapor permeability and the lowest capillary water absorption for the highest presence of large pores
(>3000 nm)
Structural compatibility of smectic sublayer: liquid crystals from oxynitrostilbene
No full textA series of dialkyldimethylammonium bromides bearing a 4,4'-oxynitrostilbene calamitic core at the end of one of the alkyl chains was synthesized. Its thermotropic liquid crystal behaviour was examined using differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction. An ordered smectic phase was identified in which the ionic ammonium bromide groups are arranged according to a square two-dimensional crystal lattice, and the oxynitrostilbene cores are tilted away from the layer normal by an angle of 54 degrees. This novel smectic structure is discussed in terms of structural compatibility of the smectic sublayers: the sublayers of the ionic groups and calamitic cores adapt their internal structure in order to become adequate for coherent superposition in a smectic structure
Identification of health and welfare parameters for rabbit production and definition of an evaluation score
No full textThe knowledge on rabbit welfare may be improved by the use of correct tools for monitoring the different aspects of rabbit
industrial farming. Therefore, the aim of this study was to define parameters related to health and welfare of animals in industrial farms with intensive husbandry. Health, management, environmental and productive parameters were firstly characterized and then a protocol to assess welfare of rabbits was define. The research was conducted on 8 industrial farms from 2004 to 2007 and around 30 inspections were done in each farm. At each visit, the health conditions were established by: (1) necropsy on animals of different productive category; (2) specific laboratory investigations based on the lesions observed; (3) checking the presence of parasites in environmental faecal samples; (4) bacteriological examination of vaginal, nasal and rectal swabs of rabbit of different age. The immune conditions and the efficacy of vaccinations were measured by determining anti-Myxomatosis and anti-Rabbit Haemorrhagic
Disease antibodies using competitive ELISAs, and anti-Encephalitozoon cunicoli antibodies by immunocarbonassay. The environmental conditions were evaluated by measuring air temperature, relative humidity, ammonia concentration and bacterial/fungal count. Finally the productive parameters were also recorded and elaborated. All the entered values were then utilized for defining a score system to establish health and welfare condition
Effect of Biomass Waste Materials as Unconventional Aggregates in Multifunctional Mortars for Indoor Application
No full textAbstractIn order to decrease energy consumption in buildings, a new way to recycle materials coming from biomasses waste in mortars was studied. For this purpose, mortars with water/cement equal to 0.5 by weight and aggregate/cement equal to 3.5 by volume were considered. Cement was replaced by hydraulic lime and sand was substituted with two different types of spruce sawdust shavings (as it is and roasted), biomass bottom ash and biomass fly ash. The results show that mortar prepared with cement has obviously a better mechanical strength and 60% lower capillary water absorption. All unconventional aggregates increase the total porosity of lime mortars. Moreover, biomass fly ash and both spruce sawdust shavings based mortars can be classified as lightweight mortar. Regardless of porosity and lightness, biomass bottom ash improves up to 150% the mechanical performance of lime-based mortars. Concerning durability, bio-based lime mortars show in general nearly twice higher capillary water absorption with respect to the sand lime mortars whit the exception of spruce sawdust shavings and biomass bottom ash. Mortars can be classified as permeable to water vapour. As it is and roasted spruce sawdust shavings are able to increase three and two times the capacity of the mortar to be a hygroscopic buffer in terms of MBV values
Comportamento a corrosione di armature zincate in calcestruzzi idrofobizzati
No full textCD-ROM a cura dell'AI
Proprietà termiche e caratteristiche spettrali dei vapori di elementi di transizione prodotti in un atomizzatore elettrotermico
No full textOxygen diffusion through hydrophobic cement-based materials
No full textThe oxygen diffusion coefficient through hydrophobic cement-based materials fully immersed in water was
determined by potentiostatic measurements on concrete and by the use of a diffusion cell on cement pastes
and mortars. The obtained results show that very high oxygen diffusion occurs through cement paste, mortar
and concrete made with hydrophobic admixture as opposed to negligible diffusion through the reference
cement matrix without admixture. Moreover, the oxygen diffusion coefficients measured through
hydrophobic cement matrices immersed in water were comparable with those reported in literature for
unsaturated cement materials in air. These experimental results appear to confirm that oxygen dissolved in
water directly diffuses as a gaseous phase through the empty pores of a hydrophobic cement matrix. This
could explain the severe corrosion of steel reinforcement embedded in cracked hydrophobic concrete
immersed in an aqueous chloride solution observed in a previous work
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