Experimental analysis of moisture uptake and dry-out in CLT end-grain exposed to free water

This paper presents the results of a series of laboratory tests of CLT end-grain moisture uptake and dry-out. We put CLT test details (TDs) in direct water contact from the end-grain edge and then left the TDs to dry for two weeks in the laboratory and in an outside shelter. Half of the TDs had their wet sides attached to another CLT detail. Fibre saturation point was quickly reached in the bottom part of the TDs during the seven-day water contact. A tendency of increasing moisture content (MC) was up to 90 mm from the wet edges, but we did not record MC levels above the critical level at that height. However, MC exceeded critical levels at 60 mm from the water level. The measured water absorption coefficient Aw was 3.51×10−3 kg/m2-s0’5. Drying was negligible for the TDs which were in contact with another CLT detail. Thus, moisture dry-out is very complicated in joints where the CLT end-grain is covered, such as the exterior wall to foundation or intermediate ceiling connection. The dry-out of CLT is not expected in a cold and humid outdoor environment once the CLT end-grain has absorbed moisture even with wet edges exposed to air.

Modelling climate related performances of building wall coatings and understanding the portability of the “Künzel” rule in different climates

How may a coating affect the hygrothermal performance of the building envelope in different climates? Years ago, Helmut Künzel, one of the fathers of Building Physics, proposed, a simple, well-known rule, relating two characteristics of a coating: its water absorption coefficient and its vapour diffusion. The “Künzel rule” (and the associated diagram), based on a model confirmed by field tests in the German climate, set an upper limit to both parameters and their product, became a German standard and a practice among experts, practitioners and manufacturers, in many European countries. This paper proposes the results of an analysis aiming to verify its portability in other climates and is based on an extensive simulation of the hygrothermal performances of a reference wall in six different climatic conditions.

Assessment of Stone Protective Coatings with a Novel Eco-Friendly Encapsulated Biocide

The conservation of stone monuments is a constant concern due to their continuous weathering, in which biofouling plays a relevant role. To enhance the effectiveness of biocidal treatments and to avoid environmental issues related to their possible toxicity, this research aims at formulating and characterizing a coating charged with an eco-friendly biocide and showing hydrophobic properties. For this purpose, zosteric sodium salt—a natural biocide product—has been encapsulated into two silica nanocontainers and dispersed into a tetraethoxysilane-based (TEOS) coating also containing TiO2 nanoparticles. The coatings were applied on four different types of stone: brick, mortar, travertine, and Carrara marble. The effectiveness of the coating formulations and their compatibility concerning the properties of coated stones were assessed. The results showed that all coatings conferred a hydrophobic character to the substrate, as demonstrated by the increase of the static contact angle and the reduction in the capillary water absorption coefficient. The transmission of water vapor of the natural stones was preserved as well as their natural aspect. Furthermore, the coatings were homogeneously distributed on the surface and crack-free. Therefore, the protective capability of the coatings was successfully demonstrated.

Influence of Sawdust Particle Sizes on the Physico-Mechanical Properties of Unfired Clay Blocks

Sawdust, which is a waste/by-product of the wood/timber industry, can be utilised as a valuable raw material in building material production due to its abundance and low cost. However, the application of sawdust in the manufacture of unfired clay blocks has received little investigation. Furthermore, the impact of different sawdust particle sizes on the properties of unfired clay blocks has not been studied. Therefore, this study screened sawdust at three different particle sizes: SP-a (212 μm < x < 300 μm), SP-b (425 μm < x < 600 μm) and SP-c (1.18 mm < x < 2.00 mm), to examine their effects on the physical and mechanical properties of unfired clay blocks. The density, linear shrinkage, capillary water absorption and flexural and compressive strengths were among the tests performed. Different sawdust percentages, i.e., 2.5%, 5%, 7.5% and 10% of the total weight of the clay, were considered. The tests results show that when sawdust was added to the mixture, the density of the samples reduced for all particle sizes. However, the linear shrinkage increased in SP-a samples but decreased in the other two particle size samples as the sawdust percentage increased from 2.5% to 10%. On the other hand, the capillary water absorption coefficient increased while the strength decreased with increasing sawdust content for all three groups. The highest compressive strength (CS) and flexural strength (FS) were achieved at 2.5% of sawdust content. Furthermore, it was observed that SP-b (CS—4.74 MPa, FS—2.00 MPa) samples showed the highest strength followed by SP-a (CS—4.09 MPa, FS—1.69 MPa) and SP-c (CS—3.90 MPa, FS—1.63 MPa) samples. Consequently, good-quality unfired clay blocks can be manufactured using sawdust up to 2.5% with particle sizes ranging between 600 and 425 μm.

Influence of glass residue on the properties of a mortar

The realization of actions aimed at sustainable development is unquestionable. As the technological improvement increases every day, the possibility of reusing different wastes to replace the use of natural resources in the development of construction materials is growing, since the wastes and byproducts from other industries have a significant representation in the volume of solid waste generated in the country. Aiming at the need to reuse waste, this work aimed to develop a multi-purpose mortar for use in construction with waste glass industry, in order to replace part of the binder material (Portland cement) by waste glass in percentages of 0, 5, 15 and 20%. The methodology used consisted of the experimental program that consists of the characterization of the materials used for the production of the multiple-use mortar, as well as the execution of technological tests of mortars in the fresh and hardened states. According to the results, it was possible to observe that the analyses made both on the residue and on the properties of the fresh and hardened state of the mixture, it was possible to verify that the influence of the residue in the mixture presented in its composition a 68% concentration of silicon oxide (silica), one of the main components of cement. In view of the aspects analyzed, it was concluded that the mortar with the replacement of Portland cement by glass waste showed better results regarding the porosity of the mortar since the capillary water absorption coefficient was the lowest among all mortars.

Built Heritage Evaluation: Manual Using Simple Test Methods

<p>This manual describes simple tests for evaluating the condition of built heritage and cultural monuments. The tests were selected for their simplicity and widespread availability, especially in countries where few institutions deal with the conservation of <a>important buildings or monuments</a> and where laboratories capable of the necessary analyses are scarce.</p> <p>Most tests can be carried out without the resources of a complete conservation laboratory. Methods include microscopy, ion test strips, the Scotch Tape test, RILEM tube water absorption, water vapor transmission, and three tests that can be run sequentially: capillary water absorption coefficient, total immersion, and evaporation curves.</p> <p>Some of these tests aid in the examination of building materials and the characterization of salts and other condition problems, which will help to determine the appropriate methods and materials for conservation and restoration.</p>

Built Heritage Evaluation: Manual Using Simple Test Methods

<p>This manual describes simple tests for evaluating the condition of built heritage and cultural monuments. The tests were selected for their simplicity and widespread availability, especially in countries where few institutions deal with the conservation of <a>important buildings or monuments</a> and where laboratories capable of the necessary analyses are scarce.</p> <p>Most tests can be carried out without the resources of a complete conservation laboratory. Methods include microscopy, ion test strips, the Scotch Tape test, RILEM tube water absorption, water vapor transmission, and three tests that can be run sequentially: capillary water absorption coefficient, total immersion, and evaporation curves.</p> <p>Some of these tests aid in the examination of building materials and the characterization of salts and other condition problems, which will help to determine the appropriate methods and materials for conservation and restoration.</p>

Hygrothermal simulation of building performance: data for Scottish masonry materials

Retrofitting thermal insulation to solid masonry walls alters their hygrothermal behaviour, which can be modelled by hygrothermal simulation software. However, such software needs values of key material properties to ensure satisfactory results and until now data has not been available for Scottish masonry buildings. This work aims to contribute to a Scotland-specific dataset of material properties for use by designers working on such buildings. Thermal conductivity, water vapour permeability, sorptivity, water absorption coefficient, hygroscopic sorption, density and porosity were all determined experimentally for selected historic and contemporary masonry materials. Within the range of materials tested three groups of materials properties emerge. Natural hydraulic lime mortars, hot-mixed quicklime mortar and earth mortar all show comparatively low density, high porosity, low thermal conductivity, high water vapour permeability and variable but generally high hygroscopic sorption. Craigleith, Hailes and Giffnock sandstones, no longer available but obtained from conservation works on historic buildings, and Locharbriggs and Hazeldean sandstones, obtained from current production, all show intermediate values of these properties. Crathes granodiorite and Scottish whinstone (from current production) show high density, low porosity, high thermal conductivity, low water vapour permeability and low hygroscopic sorption. It is shown that these materials are all relevant to Scottish buildings constructed in traditional masonry and this paper presents the first comprehensive set of hygrothermal property data for them.