Environmental impacts of natural and conventional building materials: a case study on earth plasters (original) (raw)
Related papers
Eco-efficiency of plasters for rehabilitation and new buildings
2nd International Conference on Sustainable, Environmentally Friendly Construction Materials, 2021
A review of the current state of art for air-lime, gypsum and earth based plasters for rehabilitation and new buildings, in terms of eco-efficiency, is presented. These mortars belong to Portuguese traditional architecture, responding to compatibility criteria most of the time. This factor, combined with a possible positive response to eco-efficiency evaluation, would bring interest for their application in rehabilitation as well as in new construction. To assess eco-efficiency of plasters, the considered factors are linked to the environmental impact of these products and to their contribution for occupants well-being. Some qualitative results concerning embodied energy for these mortars in a "cradle to gate" approach analysis are shown. The lack of a common, standardized and shared procedure for this evaluation seems an evidence, above all when the attempt of comparing results from different studies is made. Furthermore, common and specific characteristics mostly related to contribution for indoor comfort conditions are presented, as indicators of technical efficiency of those plasters. The potential for behaving as moisture regulators and passive removal materials not only affect users, but can also have an important role in energy savings. Lastly, durability is considered a key factor of eco-efficiency mainly to meet the purpose of minimising exploitation of raw materials. For this reason it is important to consider protective treatments or finishing system, for improving durability, always keeping in mind all the elements of the equation.
Environment and Ecology Research, 2021
Mortars based on cement and sand are common in buildings; however, cement is characterized by consuming large amounts of energy. It is stated that there is possibility of reducing emissions to the environment if soil-based mixtures are obtained from the land near the house where they are used, but this is not generally demonstrated through a functional life cycle analysis. The life cycle analysis is carried out "from the cradle to the grave." In this research, we analyzed the environmental impact of materials used in earth-buildings in Mexico, which are typical in rural houses; three coatings cases were used: one traditional cement-sand, a second based on Earth with lime and fiber, considering that it is transferred manually from the surrounding soil, and another modifying the transfer but with industrial machinery. The fiber was produced from Agave lechuguilla torrey, a plant grown in the same field of housing location; the experimental part was developed at Tampico, Tamaulipas, Mexico, to obtain the selected composition and coating thickness. The results show that the impact on the environment and climate change can be reduced by up to 65%. Using transport processes with fossil fuel-based equipment considerably increases the impact, so nearby material collection areas should be considered to reduce environmental impact effectively.
Eco-efficient earthen plasters: The influence of the addition of natural fibers
2015
Clayish earth-based mortars are been recognized, all over the world, as eco-efficient products for plastering. Apart from being a product with low embodied energy when compared to other types of plasters, their application on the interior surface of walls may give a strong contribution for the health and comfort of inhabitants. As part of an ongoing research regarding earth-based plasters this work assesses the influence of the addition of two types of natural fibresoat straw and typha fiber-wollon the characteristics of plastering mortars made with a clayish earth. Mechanical and physical characteristics were tested, showing that addition of these fibers contribute to decrease linear drying shrinkage and thermal conductivity, as well as promoting the adhesion strength of plaster to the substrate. The improvement of mechanical resistance reveal to be dependent on the type of fiber added while the hygroscopic capacity of the plaster is maintained regardless of the fiber additions.
An experimental campaign was developed to evaluate the properties of earth plastering mortars, not only at the level of workability and physic-mechanical performance but also their susceptibility for biological colonization. A ready-mixed earth mortar and several other mortars formulated with a raw clayish earth were produced. The influence of partial replacement of fine sand by a phase change material (PCM) and the addition of low amounts of oat fibres and hydrated air lime were assessed. The experimental campaign shows that the PCM completely changes the mortar workability, with a decrease on wet density. The addition of PCM and fibres decreases the bulk density and, consequently, increases the porosity of the mortars. The presence of PCM, fibres and air lime decreases the thermal conductivity. Earth mortars are susceptible to mould development, and the fibres or PCM seem to intensify their bio-susceptibility. A low addition of air lime increases pH and inhibits fungal growth though decreasing the mechanical properties. Mortars with PCM, fibres and air lime present a higher surface roughness in comparison to other mortars, including the ready-mixed earth mortar with fibres. Surface roughness was found to be an important factor influencing the level of colonization.
Key Engineering Materials, 2016
Clayish earth-based mortars can be considered eco-efficient products for indoor plastering since they can contribute to improve important aspects of building performance and sustainability. Apart from being products with low embodied energy when compared to other types of mortars used for interior plastering, mainly due to the use raw clay as natural binder, earth-based plasters may give a significant contribution for health and comfort of inhabitants. Due to high hygroscopicity of clay minerals, earth-based mortars present a high adsorption and desorption capacity, particularly when compared to other type of mortars for interior plastering. This capacity allows earth-based plasters to act as a moisture buffer, balancing the relative humidity of the indoor environment and, simultaneously, acting as a passive removal material, improving air quality. Therefore, earth-based plasters may also passively promote the energy efficiency of buildings, since they may contribute to decreasing t...
Evaluation of different raw earthen plasters stabilized with lime for bio-building exploitation
2019
The building sector generates around 5-8% of greenhouse gas emissions (GHG)[1] and the disposal of C&D waste at the end-of-life is a high environmental cost. The raw earth is a sustainable construction material with low embedded energy, available locally. It is the most ancient technique of construction, studied in recent years to reduce the environmental life cycle impact of buildings. Clay is responsible for the earth plastic behaviour and represents the binder that keeps together silt and sand grains. Earth sets through drying without chemical reactions, so it could be reinserted into the nature. At the same time, earthen constructions do not withstand weathering and develop lower mechanical performances compared with those which exploit hydraulic binders. We investigated the possibility of improving these characteristics by stabilizing earthen products with the addition of small amounts of lime preserving clay as eco-friendly binder and the full end-of-life recyclability. Four e...
Earthen Plasters Stabilized through Sustainable Additives: An Experimental Campaign
Sustainability
The earthen architecture widely spread in many countries of Europe, America, Asia, Africa, testifies to a particular material and immaterial culture. Nevertheless, it is a fragile heritage, which needs continuous maintenance. To encourage the preservation of such evidence of building techniques, an experimental campaign aimed at the development and evaluation of the performances of protective earthen plasters was undertaken. The durability of the plasters was improved through the addition of different additives, some of them traditional (such as lime and gypsum) and others innovative (geopolymers, enzymes), and resulting from industrial wastes (cement kiln dust). These additives have been selected considering low production costs and a reduced environmental impact, to improve the sustainability of the interventions. The performances of the earthen plasters in terms of efficacy (resistance to water erosion, water absorption, drilling, thermo-hygrometric cycles) and compatibility (cha...
Eco-efficient earth plasters: influence of clay content, sand particle size and support
Journal of World Architecture
Earth construction, including the use of earth mortars, has been extensively used in the past. However, with the appearance of hydraulic binders, the use of earth strongly decreased for new construction and even to repair old earth buildings, whose best solution would be the use of compatible materials such as earth mortars.Due to the innumerable advantages of earth and with the growing concern on eco-efficient construction, the interest on earth construction has resurfaced, namely on earth mortars.In order to optimize the composition of an earth plastering mortar made with a defined clayish earth and two siliceous sands with different particle size, six compositions were assessed. Mortars with different volumetric ratios were applied in two different supports (on the back of a tile and on a brick) and planar specimens were also produced. Distinct characteristics were assessed, such as their visual appearance, shrinkage, surface cohesion, surface hardness, dry abrasion resistance, u...
Environmental Earth Sciences, 2013
Three pre-mixed powdered clay-based (earthen) plasters produced in Europe and specifically designed for wall undercoating were analyzed in this paper. These materials are commercially available and successfully employed in green building practices all over the world. Their compositional and textural characteristics, as well as plastic behaviour were investigated through a multi-analytical approach: X-ray powder diffraction (XRPD), polarized light microscopy (PLM), X-ray fluorescence spectrometry (XRFS), scanning electron microscopy equipped with an energy dispersive spectrometer (SEM-EDS), mercury intrusion porosimetry (MIP), grainsize distribution (GSD) and semi-empirical tests (Atterberg Limits, Linear Shrinkage). In addition, a natural earth (a terra rossa red soil sampled in northwestern Sicily), theoretically appropriate for the production of earthen plaster, was subjected to the same analytical routine and compared with the three commercially available pre-mixed products. The achieved results allowed to individuate the compositional and textural features that primarily influence the performances of the studied earthen plasters. The obtained data are expected to be also useful in directing the selection of raw materials for local manufacture of specifically designed innovative products.