Francesca Tittarelli

Assessment of air pollutant sources in the deposit on monuments by multivariate analysis.

A proper recognition of the pollutant sources in atmospheric deposit is a key problem for any action aiming at reducing their emission, being this an important issue with implications both on human health safeguard and on the cultural heritage conservation in urban sites. This work presents the results of a statistical approach application for the identification of pollutant sources in deposits and damage layers on monuments located in different European sites: Santa Maria del Fiore, Florence (Italy), Cologne Cathedral, Cologne (Germany), Ancient ramparts, Salè (Morocco), National Museum, Cracow (Poland) and National Gallery, Oslo (Norway). For this aim, the surface damage layers on monuments and historical buildings of the selected sites were collected and analyzed, in terms of ionic and elemental composition, through application of ion chromatography and induced coupled plasma-optical emission spectroscopy. The achieved results were processed by multivariate analyses such as correlation matrix and principal component analysis in order to identify the possible origin of pollutants affecting the state of conservation of the monuments. This allowed us to assume that in all case studies the traffic emission is the main pollutant source. In the case of Ancient ramparts, Salè (Morocco), and National Gallery, Oslo (Norway), the surfaces are also under influence of marine aerosols. Moreover, concerning the Cologne Cathedral, the strong impact of the pollutants emitted by railway station was also revealed.

Thaumasite: evidence for incorrect intervention in masonry restoration

Abstract Thaumasite, as well as ettringite, are compounds which are increasingly found as deterioration products of cementitious materials subjected to sulfate attack. Thaumasite, and especially ettringite, have been abundantly reported in relation to concrete deterioration as well as, more recently, to the deterioration of cementitious mortars for masonry and for plasters. In particular, the problem appears serious in the field of repair of historical buildings, where the cementitious mortar can easily deteriorate just because of the formation of ettringite and thaumasite. However, although thaumasite is responsible for deterioration, in most cases, it may not be detected since it can be partially or almost completely removed by atmospheric agents. Many causes can be responsible for the presence of sulfates in masonry. At the same time, mortar and plaster are, in most cases, sources of calcium carbonate. Moreover, masonry is typically a porous material, which can be easily permeated by water, either rising groundwater or falling rainwater. Therefore, when cement based materials, which are in turn sources of calcium aluminates and calcium silicates, are used as binders, all of the ingredients necessary to cause thaumasite formation are present. Consequently, a compatibility issue emerges, which if not kept into proper account, will lead sooner or later to ineffective intervention.

Durability assessment to environmental impact of nano-structured consolidants on Carrara marble by field exposure tests.

The EU policy of reducing the emissions of combustion generated pollutants entails climate induced deterioration to become more important. Moreover, products applied to preserve outdoor built heritage and their preliminary performance tests often turn out to be improper. In such context, the paper reports the outcomes of the methodology adopted to assess the durability and efficiency of nano-based consolidating products utilized for the conservation of carbonate artworks, performing field exposure tests on Carrara marble model samples in different sites in the framework of the EC Project NANOMATCH. Surface properties and cohesion, extent and penetration of the conservative products and their interactions with marble substrates and environmental conditions are here examined after outdoor exposure for eleven months in four different European cities and compared with the features of undamaged and of untreated damaged specimens undergoing the same exposure settings.

Influence of Binders and Lightweight Aggregates on the Properties of Cementitious Mortars: From Traditional Requirements to Indoor Air Quality Improvement

Innovative and multifunctional mortars for renders and panels were manufactured using white photocatalytic and non-photocatalytic cement as binder. Unconventional aggregates, based on lightweight materials with high specific surface and adsorbent properties, were adopted in order to investigate the possible ability to passively improve indoor air quality. The reference mortar was manufactured with traditional calcareous sand. Results show that even if the mechanical properties of mortars with unconventional aggregates generally decrease, they remain acceptable for application as render. The innovative mortars were able to passively improve indoor air quality in terms of transpirability (70% higher), moisture buffering ability (65% higher) and depolluting capacity (up to 75% higher) compared to traditional ones under the current test conditions.

Used Foundry Sand in Cement Mortars and Concrete Production~!2010-03-27~!2010-05-03~!2010-07-07~!

Used foundry sands represent the highest amount of solid wastes generated by foundries. Classified by European Union regulations as non hazardous waste, they represent a relevant source to be reused in several industrial sectors, in building construction primarily. In present paper, the properties of mortars and concretes containing different dosages of used foundry sand (UFS) as partial replacement of sand were investigated in both fresh and hardened conditions. In particular, higher percentages of addition, but lower if referred to the whole aggregate (fine and coarse), were considered in concretes than in mortars. Both mortars and concretes were evaluated with respect to consistency of the fresh mixture and compressive strength of the hardened material. Elastic modulus determination of the hardened material was carried out on concretes. A low (10%) amount of used foundry sand does not change the mortars performances. In the presence of higher additions a workability decreasing can be outlined, and then a higher dosage of superplasticizer is required in order to keep it constant. Mechanical performances lower of about 20-30% than those of the conglomerate without used foundry sand are observed. The higher penalization it seems to concern to the conglomerates of better quality (i.e. lower water-cement ratio).

Binders alternative to Portland cement and waste management for sustainable construction—part 1:

This review presents “a state of the art” report on sustainability in construction materials. The authors propose different solutions to make the concrete industry more environmentally friendly in order to reduce greenhouse gases emissions and consumption of non-renewable resources. Part 1—the present paper—focuses on the use of binders alternative to Portland cement, including sulfoaluminate cements, alkali-activated materials, and geopolymers. Part 2 will be dedicated to traditional Portland-free binders and waste management and recycling in mortar and concrete production.

SUSTAINABLE AND DURABLE REINFORCED CONCRETE CONSTRUCTION

Recycled aggregates used in combination with high-volume fly ash is an example of sustainable construction material usage as it represents a judicious use of resources by recycling by-products, which results in a lower environmental impact through reduced carbon dioxide (CO2) emissions and reduced natural aggregate extraction. The related concrete mixtures yield acceptable mechanical performance. The aim of the experimental work reported herein was to study the effect of recycled aggregate and/or fly ash on carbonation and chloride penetration depth, as well as the effect on corrosion behavior of either bare or galvanized steel in cracked reinforced concrete (RC). The concrete mixture contained equal amounts of fly ash and cement. Results show that introduction of the sustainability concept in concrete technology by using recycled aggregate and/or fly ash did not cause any deleterious effects on durability of RC specimens in terms of both chloride and CO2 penetration, and reinforcement corrosion in cracked concrete.

Valorisation of GRP Dust Waste in Fired Clay Bricks

In Europe, the total amount of Glass Reinforced Plastic (GRP) waste is increasing. In order to valorise GRP dust (GRPd) waste and to reduce the consumption of nonrenewable resources in building materials, GRPd has been already investigated in cementitious materials where it gives even an improvement in some performances of the final products. Valorisation of GRPd waste in the production of bricks can be considered as a further alternative. In this paper, GRPd waste was substituted to the clay volume at 5% and 10% for the manufacturing of fired clay bricks. All specimens were subjected to a firing temperature of 850°C for 6 hours, then tested and compared in terms of porosity, compressive and flexural strengths, density, and water absorption. Despite a decrease in compressive strength up to 46% with 10% of GRPd substitution and an increase of water absorption from 14% to 29% with 5% and 10% of GRPd substitution, respectively, an increase in terms of lightness (about 10%), maximum flexural strength (up to 31%), and deflections at the maximum load (up to 130%) has been registered by specimens with 10% of GRPd substitution.

Use of Hydrophobic Agents as Concrete Admixtures

Environmental-induced degradation of reinforced concrete structures can be reduced by preventing water penetration into concrete pores using hydrophobic agents as concrete admixtures. In order to point out problems related to their practical use, the effectiveness of hydrophobic admixture on cement pastes with different w/c, and in the presence of other commonly used chemical admixtures, was studied. Capillary water absorption and the contact angle between water drops and the cement paste surface were evaluated. Changes in the cement paste porosity due to the hydrophobic admixture were studied by porosimetric analysis. Results obtained show that the hydrophobic admixture is able to reduce the prolonged capillary water absorption in all cement pastes by about 70%, regardless of how it is added. The hydrophobic agent appears even more effective during the initial phase of water absorption, especially with increasing w/c.

Waste foundry sand

Abstract Used 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.