In the context of stricter indoor air quality regulations, earthen plaster shows great potential because of its properties as a building material.
Usually the term plaster refers to a wall covering made from earth, lime or gypsum, while stucco uses a cement or synthetic binding element.
Notable clay minerals involved in this process include montmorillonite, chlorite and illite, each adding distinct properties to the composition.
Consisting of tiny mineral particles derived from its original rock material, sand is predominantly made up of silicon dioxide (quartz) and is recognized as a non-reactive substance.
Sand is incorporated into the plaster mixture not just for structural purposes but also plays a vital role in minimizing the likelihood of cracks during the drying process.
This dual impact indicates the careful balancing act required in soil composition to achieve both structural integrity and controlled moisture absorption.
In the context of improving adhesion and compatibility with different substrates, fibers may be introduced to earthen plasters without compromising their environmental profile.
Research indicates that the inclusion of natural fibers, moderately increases open porosity, facilitating improved pore interconnection.
The addition of fibers to plasters is observed to have various benefits, including reduced density, minimized shrinkage cracks, and improved adhesion strength.
Many commonly used additives originate either from natural sources or result from industrial and agricultural processes, providing a cost-effective means to refine the characteristics of clay plaster.
Due to the absence of a comprehensive theoretical model explaining these effects, predicting the impact of a specific additive in a particular plaster mixture relies on empirical testing for each combination.
The primary utilization of additives revolves around addressing inherent weaknesses in clay plaster, such as dry shrinkage, mechanical strength, or adhesion.
Furthermore, certain additives aim to enhance properties crucial for indoor applications, including thermal resistance and moisture buffering capacity.
They can serve many purposes: some biopolymers can act as a glue holding the matrix together, while others help fill cavities and supplement the particle distribution, both will increase the cohesion.
Other additives include: stearate, tallow, tannin, leaves and bark of certain trees,natural gums and glues, kelp, powdered milk, or the blood of livestock.
[vague] Manure also contains small natural fibers that provide additional tensile strength as well as reduce cracking and water erosion.
), the age of the plaster, and the amount of other natural binder(s) (such as lime, wheatpaste, cactus juice, hardening vegetable oil, casein and other proteins, etc.)
Cactus juice works well because it contains pectin, a water-soluble long-chain carbohydrate that acts as the binding agent to increase the adhesion of an earthen plaster.
Research shows that the addition of paper waste improved the moisture buffering capacity of clay plaster, while also lowering its density.
In a human body, ozone reacts with tissue cells that promote inflammation and increased permeability of the epithelial lining fluid, which allows for greater penetration of pollutants from lung air into the blood stream.
The high deposition velocities exhibited by clay wall plaster or paint may be due to iron or aluminum catalyzed decomposition of ozone.
Field test show that materials as clay paint and carpet become less reactive over interval of years, probably due to slow oxidation of organic coatings.
Evidence have shown that indoor air parameters: relative humidity, temperature and ozone concentrations influence test results.
They claim that ozone can oxidize airborne gases, and particulates, to simple carbon dioxide and water vapor and that it can also remove unpleasant odors.
In scientific literature, references to the favorable influence of clay plasters on indoor air quality are often superficial, with many studies primarily focusing on the hygroscopic behavior or
Those minerals include kaolinite, halloysite, montmorillonite, bentonite, saponite, vermiculite, illite, sepiolite and palygorskite, zeolites (more used as an additive), chlorite and smectite.
Especially when a photocatalyst is used, the adsorption reaction can be very effective (up to 90 % removal efficiency) according to some studies, in improving indoor air quality and olfactory comfort.
Compared to other wall coverings, they are less toxic and energy-intensive, as little energy is required in extraction, production and processing, making them attractive to environmentally conscious people.
It is a water-vapor permeable material and has a high storage/heat release capacity, contributing to thermal comfort, improved air quality and energy efficiency.
The downside, however, is their mechanical strength and resistance to the action of climatic factors, their reduced degree of compatibility with classic finishing materials currently available on the market.