Research Development in Silica Aerogel Incorporated Cementitious Composites—A Review

Abstract

This paper presents an analysis of research results for silica aerogel cement composites over the past twenty years. Recently, two trends in the development of these composites have been noted, towards structural applications and towards ultralight composites for coatings and renders. Ongoing research shows that important aspects of cementitious composites with good mechanical performance are the proper selection of aggregates and improved adhesion at the silica aerogel–cement binder interface, which will guarantee high compressive strength with the lowest possible thermal conductivity. The best physicomechanical performance of aerogel cement composites with low thermal conductivity below 0.03 W/(m·K) was obtained when cenospheres and aerogel were used in a weight percentage of 5%. In turn, the prerequisites for using aerogel cement composites as coatings for energy-efficient building façades are the use of large amounts of silica aerogel as a substitute for lightweight aggregates or the selection of an optimal composition of lightweight aggregates and aerogel, ensuring the lowest possible thermal conductivity coefficient. Other important standpoints are water transport and moisture protection of the silica aerogel-based coatings. Therefore, in recent years, more and more elements of the hygrothermal performance, porosity and durability of silica aerogel cement composites have been developed. The article also points out the weaknesses of the application of silica aerogel in the cement matrix, the most important of which are the lack of adhesion at the boundary of the aerogel–cement binder, the increased porosity of the composite, the high water absorption capacity and the significant decrease in compressive strength with large volumes of silica aerogel. Solving these issues will certainly contribute to the wider applicability of these materials in the construction industry.

Thermomechanical Performance Assessment of Sustainable Buildings’ Insulating Materials under Accelerated Ageing Conditions

“…This contributes to better insulation properties. Aerogels have low bulk densities, mainly due to their very high porosity (80–99.8%) [ 44 ], with a typical open porous structure composed of silica secondary particles with diameters inferior to 10 nm and pores smaller than 50 nm [ 45 ].…”

Cost-Effective Preparation of Hydrophobic and Thermal-Insulating Silica Aerogels

“…They then subject it to a series of processing steps, including sols, glass-fiber composites, gels, aging, hydrophobic modifications, solvent replacements, and supercritical drying, to produce silica aerogel composite glass-fiber mats [ 28 , 29 , 30 , 31 ]. While the aerogel insulations produced by these processes have secured their positions in the global market, they remain costly, preventing their widespread adoption in price-sensitive sectors such as construction [ 32 , 33 , 34 , 35 ]. The production costs of aerogel materials are primarily related to the silicon sources and hydrophobic modifiers.…”

Mechanical and Thermal Properties of an Energy-Efficient Cement Composite Incorporating Silica Aerogel

“…The presence of the capillaries, as well as the fragility of the silica aerogel itself and the increased porosity of the cement matrix, determine the mechanical properties of the composite. Table 1 presents a review of the amount of aerogel mixed into cementitious composites [22].…”