At present, there are still some problems that need to be solved during the large-scale promotion and application of silica aerogel in the construction field.
1. Cost issue
Silica aerogel, as a cutting-edge new material, has a high technical threshold, requires significant investment in research and development and industrialization equipment, and the scale of industrialization is small, resulting in high costs. The construction industry has a huge demand for aerogel materials, and the high cost is currently the main factor restricting the large-scale promotion and application of aerogel materials in the construction field.
The preparation of aerogel mainly includes supercritical and normal pressure processes. The supercritical process has the disadvantages of large one-time equipment investment, high equipment requirements, and high risk of high-pressure operation. The normal pressure process is a trend. Compared with the supercritical preparation process, the normal pressure drying process can use inexpensive sodium silicate as raw material, does not require special pressure equipment, has high production safety, but also has problems such as long production cycle and low drying efficiency.
To address these issues, efforts should be concentrated on conducting relevant technological research, strengthening the improvement and optimization of aerogel production equipment, and improving the drying efficiency. Only by breaking through these technical bottlenecks of the normal pressure process can continuous low-cost production of aerogel materials be achieved, and aerogel materials can be promoted on a large scale in the construction field.
2. Strength issue
Pure aerogel materials have the disadvantages of low strength and high brittleness, and cannot be directly applied. Domestic and foreign researchers are continuously conducting in-depth studies on aerogel building materials to overcome their shortcomings. Scientists have produced aerogel composite materials with excellent insulation performance and certain strength by combining aerogel with other materials.
For example, using inorganic and organic fibers as substrates, by adding different substrates during the preparation of aerogel, aerogel glass fiber mats, aerogel ceramic fiber mats, and aerogel pre-oxygenated fiber mats can be produced;
By combining aerogel mats with calcium silicate boards or gypsum boards, nano-aerogel composite insulation boards can be prepared; by adding aerogel to the granulation process of polymer materials, mother mixtures containing aerogel can be prepared, thereby obtaining aerogel fabrics with excellent thermal insulation performance and light weight;
By combining aerogel with various film-forming agents, various nano-functional coatings with different properties can be prepared. Compared with pure aerogel, although the addition of other materials reduces the insulation and heat preservation performance of aerogel materials, their mechanical properties have been significantly improved, which is conducive to their large-scale promotion and application. With the increasingly mature preparation and application technologies of aerogel, the continuous expansion of product production scale, and the guidance and support of national industrialization policies, silica aerogel will be widely used in the building insulation engineering field.
3. Product system construction issue
The currently available aerogel insulation and heat preservation products on the market mainly include aerogel glass, aerogel mats, aerogel coatings, aerogel sheets, aerogel pastes, and aerogel boards. The product types are single and have not yet formed a system, and their application construction processes have obvious limitations.
By improving the performance of aerogel composite materials, further expanding the application forms of aerogel in green buildings, forming a mature and complete product system, establishing relevant product standards, is the inevitable trend for the application of aerogel composite materials in the low-carbon building field.
4. Standard issue
With the continuous improvement of building energy-saving requirements, the gradual promotion of ultra-low energy buildings and near-zero energy buildings, higher requirements are put forward for the functional durability and safe structure of insulation materials. The existing national industry standard JGJ 144-2019 "Technical Regulations for External Wall External Insulation Engineering" cannot meet the requirements of the national mandatory standard (GB 55015-2021).
In order to implement the national energy conservation and emission reduction policies and achieve the goals of carbon peak and carbon neutrality, it is necessary to incorporate silica aerogel materials into the new standards and formulate relevant technical standards to regulate the design, construction and acceptance of building insulation systems.
In recent years, in response to the requirements of national carbon neutrality and carbon peak, governments at all levels have introduced many policies and guidelines to promote new materials, new technologies and low-carbon building development.
The Central Committee of the Communist Party of China and the State Council issued the "Opinions on Completely Accurately and Comprehensively Implementing the New Development Philosophy and Doing a Good Job in Carbon Peak and Carbon Neutrality Work", and the State Council issued the "Action Plan for Carbon Peak Before 2030". Both of them proposed to promote the research and application of new materials such as aerogel.
The Central Committee of the Communist Party of China and the State Council issued the "Opinions on Promoting Green Development of Urban and Rural Construction" proposing to vigorously promote ultra-low energy consumption and near-zero energy consumption buildings and develop zero-carbon buildings.
On September 22, 2021, the government released the "Opinions of the Central Committee of the Communist Party of China and the State Council on Completely Accurately and Comprehensively Implementing the New Development Philosophy and Doing a Good Job in Carbon Peak and Carbon Neutrality Work", stating: Promote the research and application of new materials such as aerogel, vigorously develop energy-saving buildings, and comprehensively promote green and low-carbon building materials.
The National Development and Reform Commission released the "National Key Energy-Efficiency and Low-Carbon Technology Promotion Catalogue" (2019) and the Ministry of Industry and Information Technology released the "National Industrial Energy Efficiency Technology and Equipment Recommendation Catalogue (2020)" including aerogel materials in the energy efficiency and application catalogue of technologies. Although there are still some problems in the application of aerogel in the building field, from the perspective of national policies and guidelines, it is imperative to apply aerogel materials in the field of building energy conservation. With the joint efforts of various universities, research institutions and enterprises, these problems will eventually be resolved. Aerogel materials will eventually be widely used in low-carbon building fields and make due contributions to the realization of the national carbon peak and carbon neutrality goals.