A material characterization and embodied energy study of novel clay-alginate composite aerogels

Abstract

There is a growing incentive within the construction industry to design low energy buildings which incorporate increased levels of insulation whilst also encouraging the use of 'green' materials which have a low environmental impact and can contribute positively to sustainable building strategies. Silica aerogels have received an increasing amount of attention in recent years as a contemporary insulation material, but their widespread use is currently hindered by high costs and their high embodied energy. This research project explores the development of a composite insulation material proposed as an alternative to silica aerogel, which consists of natural components including clay and a biopolymer obtained from seaweed known as alginate. Prototype specimens have been developed and characterised in terms of their mechanical properties and microstructure allowing comparisons to be made between five alginate types, each obtained from a different seaweed source. Whilst all of the composites tested offered an improvement over the control sample, the results also demonstrated that the type of alginate used has a significant influence on the compressive strength and modulus values of the resulting composite materials. An analysis of the production process additionally demonstrated that the freeze-drying element can have a significant impact on both the environment and financial costs of producing such a material.

Life Cycle Assessment of Aerogels: A Critical Review

“…This characteristic enhances their desirability concerning sustainability and environmental considerations and makes them potential alternatives to silica aerogels [87][88][89][90][91][92]. Clay-based composite aerogels might substitute silica aerogels, but the exact environmental impact of adding synthetic or bio-based additives remains unclear [92]. Alginate, one of the most abundant renewable natural polysaccharides, is extracted from brown algae and has gained attentions in aerogel studies [93][94][95] due to a number of merits such as nontoxicity, biocompatibility, hydrophilicity, nonimmunogenicity, etc [96,97].…”

“…The embodied energy of alginate-clay aerogels matches that of silica aerogel monoliths but surpasses commercially available silica aerogel blankets. Hence, relying on natural, renewable materials doesn't guarantee superior environmental performance compared to silica-based aerogels [92].…”

Sample key features affecting mechanical, acoustic and thermal properties of a natural-stabilised earthen material

“…The physical properties of different formulations of earth materials have been studied on their own, or by comparison with other building materials. In most cases by addressing their mechanical performance [15][16][17]. The analysis of thermal performance of earth-based materials has been also widely studied in the literature [18][19][20][21][22][23][24][25][26][27].…”

Ultralight and Hydrophobic Palygorskite-based Aerogels with Prominent Thermal Insulation and Flame Retardancy

“…But these techniques require high pressure and temperature, making them energy-intensive and cost-ineffective. 12−14 From a cost-effective and environmentally friendly point of view, the freeze-drying method has been actively used as a way for fabricating aerogels, such as metal, 15 silicon, 16 carbon, 17,18 cellulose, 19−21 graphene, 22,23 clay, 24 etc. Clay is the most abundant natural mineral resource in the world, which with natural porous microstructures and nonflammable components, which make it promising in the field of thermal insulation and flame-retardancy.…”

“…Flame retardancy (FR) plays a vital role in insulating and building applications. − Aerogels are solid materials with a three-dimensional network structure of nanoparticles. − These aerogels are characterized by low density and high porosity and are considered the most promising FR candidate. , Supercritical drying method is the most used method for preparing aerogel over the decades. But these techniques require high pressure and temperature, making them energy-intensive and cost-ineffective. − From a cost-effective and environmentally friendly point of view, the freeze-drying method has been actively used as a way for fabricating aerogels, such as metal, silicon, carbon, , cellulose, − graphene, , clay, etc. Clay is the most abundant natural mineral resource in the world, which with natural porous microstructures and nonflammable components, which make it promising in the field of thermal insulation and flame-retardancy. − In the 1950s, Mackenzie first reported a neat clay aerogel prepared by montmorillonite suspensions through freeze-drying .…”