298 research outputs found
Miglioramento delle prestazioni di materiali cementizi capaci di ridurre la concentrazione di gas serra
No full textProject Coordinator: Francesca Tittarelli - UdR Università Politecnica delle Marche, Local Coordinator: Luca Bertolini - UdR Milano Politecnic
Progetto Prisma 07Miglioramento dele prestazioni di materiali cementizi capaci di ridurre la concentrazione di gas serraRelazione sul 2° anno di attivitàUnità di Ricerca: Università Politecnica delle Marche
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Oxygen 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
Effect of low dosages of waste GRP dust on fresh and hardened properties of mortars: Part 2
No full textPart 1 of the work reported that by replacing 5–10% of sand volume with GRP dust, workability, autogeneous
shrinkage, deformability and total porosity, though with a smaller average radius, of mortars
increased, thereby reducing significantly the mechanical performance, when wet curing conditions are
adopted. However, the risk of cracking induced by restrained shrinkage and the capillary water absorption
is lower in the presence of GRP dust, leading to enhanced durability of GRP mortars when used as
supporting role. Therefore, in the present work, plaster mortars manufactured by replacing 0–2.5–5%
of sand volume with GRP dust were characterized. For comparison, the addition of an hydrophobic
admixture at different dosages was also considered. Permeability is not significantly reduced by the
low addition of GRP dust, but it is slightly increased by silane addition. Thermal insulation properties,
capillary water absorption and resistance to efflorescence are better with waste GRP dust addition, especially
when combined with silane
Applicazione delle tecniche di monitoraggio alle strutture in calcestruzzo armato
No full textPubblicato su CD Ro
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
Effectiveness of flexible polymer-cement coatings and hydrophobic admixtures against corrosion of steel in reinforced concrete
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Waste foundry sand
No full textUsed foundry sands (UFSs) represent the highest amount of solid wastes generated by foundries. Classified by European Union regulations as nonhazardous waste, they represent a relevant source to be reused in several industrial sectors, in building construction primarily. In this chapter, the physical and chemical properties of UFSs have been reported, with particular attention on metal content and relative leaching behavior. The state of the art on modern engineering applications and the role of UFSs in green and sustainable construction have been described
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