Although the energy structure has been gradually enriched in recent years, China, as the world’s largest producer and consumer of coal, still accounts for more than 50% of resources. Therefore, in this paper, the high carbon fly ash raw ash (HCFARA) was mechanically activated, and the flotation was treated to obtain decarburized fly ash (DFA) with a loss on ignition of 1.18%, water demand ratio of 101% and strength activity coefficient of 74.5%. With the exception of for water demand ratio, the rest meet the national requirements for the use of Class I fly ash. The foam concrete was prepared by partially replacing cement with decarburized fly ash in different proportions and at different water-to-cement ratios (0.3, 0.4 and 0.5) in order to study its dry density, porosity, compressive strength and thermal conductivity. The results show that the porosity of foam concrete grows with the increase in water-to-cement ratio and fly ash replacement rate. In addition, the dry density and thermal conductivity of the prepared foam concrete can meet the requirements of A05 grade foam concrete (Density less than 500 kg/m³, thermal conductivity less than 0.12 W/(m·k)). The compressive strength can meet the requirements of C0.3 grade foam concrete (Minimum use standard).

To improve forestry solid waste reuse, reduce building energy consumption, and increase building capacity, preparing lightweight concrete with new materials has gained recent attention. This paper used waste wood and expanded perlite (EP) to design lightweight thermal insulation recycled concrete (LTIRC) with different volume admixtures. Compared to mineral aggregate, wood aggregate (WA) and EP show large differences in water absorption, particle morphology, density, and crushing index. Therefore, this paper comprehensively evaluated the dry density, mechanical properties, thermal properties, chloride ion permeability, and frost resistance of LTIRC. The results showed WA and EP introduction effectively reduced concrete bulk weight and met the dry density standard for lightweight concrete. Regarding thermal insulation performance, both WA and EP are characterized by porous, low–density, and low thermal conductivity. Consequently, LTIRC thermal conductivity was reduced by up to 76.5% versus conventional concrete, effectively increasing resistance to heat flow through concrete and providing potential for building energy savings. Additionally, WA and EP addition caused LTIRC to experience mechanical and durability property deterioration. However, some LTIRCs achieved over 80% of the strength of natural aggregate concrete. Moreover, WA addition inhibited internal crack generation in LTIRC and slowed concrete damage from increased WA and EP dosage. The maximum mass loss of LTIPC was 2.72% after 100 freeze–thaw cycles. LTIPC precast panels are suitable for preparing low–carbon insulated building wall panels.

In order to improve the application of forestry by-products, This study explores the possibility of using waste wood flour to prepare geopolymer recycled foam concrete (GRFC) in architectural applications to reduce the use of mineral aggregates and improve the thermal insulation performance of the concrete. Compared with mineral aggregate, waste wood flour has advantages in density, toughness and water absorption. In addition, the addition of waste wood powder and foam at the same time will change the structural morphology of ordinary foam concrete. Therefore, this experiment explores the water retention performance, thermal insulation performance, mechanical properties (compressive strength, flexural strength, bond strength), toughness, shrinkage rate and compactness under different foam and waste wood powder (WFA) content, which makes an exploration for replacing ordinary mortar and ordinary foam concrete.The results showed that the addition of WFA strengthens the stability between pores in the honeycomb structure, and inhibits the loss of foam in the newly mixed slurry due to different internal and external humidity. It is also an effective way to improve the water retention performance, thermal insulation performance and embrittlement of ordinary mortar and foamed concrete. However, foam seems to have a negative effect on interfacial transition zone (ITZ) of wood flour and cement pastes.