147 research outputs found
Combined multianalytical approach for the characterization of commercial bricks with a view to their technical use.
No full textBrick is a construction material used in buildings since Roman times and still used in modern constructions for its own technical features and aesthetic qualities. The raw materials and the firing temperatures are closely related with the characteristics of fired products (Riccardi et al., 2009). During the firing process mineralogical and textural transformations occur (and resembles the high-temperature metamorphism) which produces anartificial material characterized by asignificant porosity. Porosity is an important parameter to evaluate the durability of bricks, especially in aggressive environments, e.g. those in which salts and frost are present (Cultrone et al., 2004). This work aims to develop a combined multianalytical approach for studying the relationships between mineralogical-textural and physical-mechanical properties and decay behavior of five types of industrial bricks. They have been chosen in order to define the influence of different compositions and firing temperatures on the development of different mineralogy, micro-texture and porosity
Composición de los dorados en la fachada de la sacristía de la iglesia de S. Maria del Carmine (Pavía, Italia)
No full textEffects of using tea waste as an additive in the production of solid bricks in terms of their porosity, thermal conductivity, strength and durability
No full textIn this paper, we investigated the use of tea waste as an additive in the production of traditional bricks. This could provide several environmental and economic benefits, as well as improving thermal insulation in construction. To this end, we produced brick samples with 0, 5 and 10 w% of tea waste mixed with a clayey material from Teruel (Spain) that was rich in quartz and phyllosilicates and had smaller amounts of carbonates. These samples were fired at 800, 950 and 1100 °C in an electric oven. We then analysed and discussed their chemical, mineralogical, textural and physical-mechanical behaviour and evaluated their durability in response to salt crystallization. The pore system of the bricks was examined using a combination of different analytical techniques (hydric tests, mercury intrusion porosimetry and digital image analysis). We also evaluated their thermal conductivity and observed that an increase in the firing temperature and the amount of tea waste altered the texture of the bricks, increasing their porosity. This happened above all at 1100 °C, where it led to the appearance of a new family of pores and increased the porosity to about 39% for bricks made with 10 w% added tea waste. The increased porosity made the bricks lighter. The bricks made with tea waste showed higher levels of water absorption and poorer mechanical strength. Our results suggest that the addition of tea residues strongly decreases the thermal conductivity and heat diffusion capacity of the bricks. They could therefore be used as lightweight bricks for the thermal insulation of buildings
Characterization of the pore system of commercial bricks for restoration: a new perspective combining 2D and 3D imaging and traditional methods.
No full textDuring the firing of bricks, mineralogical and textural transformations produce an artificial aggregate characterised by significant porosity. Particularly as regards pore-size distribution and the interconnection model, porosity is an important parameter to evaluate and predict the durability of bricks. The pore system is in fact the main element, which correlates building materials and their environment (especially in cases of aggressive weathering, e.g., salt crystallisation and freeze-thaw cycles) and determines their durability. Four industrial bricks with differing compositions and firing temperatures were analysed with ?direct? and ?indirect? techniques, traditional methods (mercury intrusion porosimetry, hydric tests, nitrogen adsorption) and new analytical approaches based on digital image reconstruction of 2D and 3D models (back-scattered electrons and computerised X-ray micro-Tomography). The comparison of results from different analytical methods in the ?overlapping ranges? of porosity and the careful reconstruction of a cumulative curve, allowed overcoming their specific limitations and achieving better knowledge of the pore system of bricks
Technological features of glazed Protomajolica ware from Benevento (Italy)
No full textThe production of glazed ceramics in Italy started in 13th century, following Islamic tradition and techniques. Protomajolica samples from two medieval archaeological sites in Benevento were analyzed from mineralogical and petrographical points of view to identify and characterize the local production of fine glazed wares. Samples are represented by jugs, amphorae, bowls and dishes finely decorated and covered by thin inner and/or outer glazed surfaces. The colour of almost all the investigated sherds varies from creamy to orange even though, from the same archaeological levels, dark grey coloured ceramic fragments likely affected by overburning of the paste (kiln refuses) were collected.Optical microscopy observations, chemical (XRF) and physical (XRD) analyses allowed to reconstruct the steps of the manufacture process, and to identify a homogeneous group of samples likely belonging to a local production area of Protomajolica, a ceramic class widespread over the Central-Southern Italy between the 13th and the 15th century
The manufacture of natural hydraulic limes: Influence of raw materials' composition, calcination and slaking in the crystal-chemical properties of binders
No full textThis study aims to achieve an in-depth understanding of the manufacturing process of natural hydraulic lime
(NHL) by assessing the influence of raw materials' chemical- mineralogical composition and the effect of the
slaking process. NHLs with variable hydraulicity were manufactured using 56 raw materials from carbonate
outcrops in Andalusia (Spain). This study shows that siliceous limestones with microcrystalline quartz generate
hydraulic phases after calcination. However, when the amount of this reactive silica exceeds 18% by weight, CaO
is not formed, and only calcium silicates appear. It was also found that slaking of NHL leads to partial hydration
of the most reactive calcium silicates, reducing the expected reactivity of the lime. Instead, exposure of NHL
quicklimes to environmental relative humidity promotes the formation of disordered portlandite and reduces the
partial hydration of hydraulic phases. Our findings demonstrate that standard slaking can be replaced by
alternative methods for the studied binders.State Research Agency (SRA) and the
Ministry of Science and Innovation under the Research Project PID2020-
119838RA-I00Regional Ministry of University Research and
Innovation of the Junta de Andalucía and FEDER (a way of making
Europe) B-RNM-188-UGR20Junta de Andalucía Research
Group RNM17
Ceramic replicas of archaeological artefacts in Benevento area (Italy): Petrophysical changes induced by different proportions of clays and temper.
No full textThe Gran Potenza clay and the Pomici di Avellino pyroclastics, respectively the clay sediments and temper of the typical ceramic manufacture in Benevento area (Italy). were mixed in different proportion and fired at 850 degrees, 900 degrees and 950 degrees C. These experimental replicas were compared with historical ceramic products of Benevento. The similarities and/or differences between archaeological materials and replicas (in terms of amount of temper, firing temperature, pore system, etc.) have been discussed. The whole data confirm the wide utilization of the local available clayey raw material and the Pomici di Avellino, and give a new contribution on the petrophysical modifications of volcanic-rich ceramic pastes that occur in the firing temperature range comprised between 850 degrees and 950 degrees C. Some peculiar features in the historical manufacturing are also reported
How to face the new industrial challenge of compatible, sustainable brick production: Study of various types of commercially available bricks
No full textIn the view of a sustainable production responding to the important challenges to which industrial research is currently facing, this research is addressed to define the more appropriate brick types, among those here studied, in terms of mechanical resistance and durability, as well as the esthetic qualities. More in detail, five industrial bricks, produced with three types of clay and fired at four temperatures (600, 950, 980, 1050 °C), were analysed with a combined multianalytical approach to determine relationships between mineralogical-textural and
physical-mechanical properties and decay behavior. Samples fired at 1050 °C showmore complete mineralogical evolution and have the best mechanical resistance, but are the most sensitive to the water absorption. Instead, samples fired at the lowest temperature (600 °C) have the best pore interconnections and the lowest coefficient of capillarity, however, the absence of new silicates and melting make them the weakest under load and decay tests. Lastly, bricks produced at firing temperatures of 950 °C and 980 °C generally show intermediate behavior. These results indicate how bricks produced form the same or similar mix design and fired at different temperatures show different reactions to decay and mechanical resistance, allowing the industry to identify the limit of applicability of these materials in various contexts
Free water absorption (a and b) and drying (c and d) tests.
No full text<p>Curves in a and c represent the behaviour of the three hemp lime mixes whilst curves in b and d refer to a group of mortars made with aerial lime and stone aggregate and different binder-to-sand ratios (from Arizzi and Cultrone, 2014). The weight variation (ΔM/M, in %) of the three hemp lime mixes is represented as a function of the square root of time (t, min<sup>-1/2</sup>); the inset in (a) shows the first minute of the water absorption curves; the water absorption coefficient (C<sub>a</sub>, in g min<sup>-1/2</sup>) and drying index (D<sub>i</sub>) are indicated in the caption of Fig 4(a) and 4(c), respectively. Arrows indicate the time in minutes (min), hours (h), days or weeks.</p
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