What is the best mix ratio of foam concrete?

Lightweight concrete, also known as foamed cement, foam concrete, etc., is a new energy-saving building material that is waste-free, environmentally friendly, energy-saving, low-cost, and non-combustible. Foam concrete is a concrete that contains a large number of small closed pores and has considerable strength by introducing air or nitrogen, carbon dioxide, oxygen and other gases into the concrete slurry according to the application needs through chemical or physical methods. products. Foam concrete is usually made by mechanically preparing an aqueous solution of foam agent into foam, and then adding the foam to a slurry composed of siliceous materials, calcium materials, water and various admixtures, etc., and then mixing, stirring, and casting. , a porous material formed by curing.
1. Features

① Lightweight and high strength

Foam concrete has low density. The density grade of commonly used foam concrete is 300-1200kg/m3, which is equivalent to 1/2 of ordinary concrete. 5—1/10. The compressive strength is greater than 0.25Mpa, and foam concrete products of different strengths can be produced according to building design requirements. The use of this material in the internal and external walls, floors, surfaces, columns and other building structures of buildings can generally reduce the weight of the building by about 25%, and some can reach 30%-40% of the total weight of the structure. In recent years, ultra-light foam concrete with a density of 160 kg/m3 has also been used in construction projects. Due to the low density of foam concrete, it can significantly reduce the weight of the building, improve the load-bearing capacity of the structure, and enhance the earthquake resistance of the building. Therefore, using foam concrete in construction projects has significant economic benefits.

② Thermal insulation

Because foam concrete contains a large number of closed small pores, it has good thermal performance. Foam concrete with a density level of 300-1200kg/m3 has a thermal conductivity of 0.06 -0.3W (M.K). Foam concrete is used as building wall and roof materials, which has good thermal insulation and energy-saving effects.

③ Good sound insulation and fire resistance

Foam concrete is a porous material with an attraction capacity of 0.09-0.19%. It has good sound insulation performance and is used in building floors, highway soundproofing panels, and underground buildings. This material can be used as a sound insulation layer in areas such as the top floor. Different from traditional sound insulation materials, foam concrete is inorganic and non-combustible, so it has good fire resistance and can improve the safety and fire protection performance of buildings.

④ Low elasticity and earthquake resistance

The porosity of foam concrete gives it a low elastic modulus, allowing it to have good absorption and dispersion of impact loads. At the same time, the lightweight and high-strength characteristics of foam concrete can effectively reduce the load of the building by 20%-40%. The smaller the load of the building, the stronger the earthquake resistance.

⑤ Fast construction speed

On-site pouring and mechanized construction, the construction speed is 1/3 faster than polystyrene foam boards.

2. Raw materials of foam concrete

① Cementitious material

Cementing material is one of the main raw materials indispensable for foam concrete, which plays a bonding role. According to the purpose, cementing materials can be calcareous materials, magnesite materials, and gypsum materials. Among them, Portland cement is the most commonly used cementing material for foam concrete. Cement of different grades has different setting strength and setting time. Even cement of the same grade has different compositions due to different manufacturers. Therefore, in principle, large-scale construction of the same cementitious material can only be carried out on the basis of small trials.

② Foaming agent

Foaming agent is the general name for foaming agents, foam stabilizers, water-binding agents and other additives (compound foaming agents include the above additives) . Foaming agents are substances that react chemically and produce gas. Foam stabilizers refer to surfactants with foam stabilizing effects, such as sodium dodecylbenzene sulfonate, hydrolyzed protein, etc. Additives such as water-binding agents refer to substances that can interact with the hydrophilic end of the surfactant through hydrogen bonds and strongly adsorb water molecules and bubble surfaces, such as polyacrylamide, arabic gum, etc.

③ Aggregate

Depending on the purpose and resource availability, aggregates can include fly ash, slag powder, sand, stone powder, ceramsite, pumice, expanded perlite, etc. (also (can be omitted). Among them, fly ash and slag powder are waste materials that are in line with the national industrial energy-saving policy and have the greatest application and development value.

④ Additives

Additives include water reducing agents, stabilizers, coagulants, early strength agents, waterproofing agents, etc., which can be added according to the use and construction conditions of foam concrete (also (can be omitted).

Water generally accounts for 60% of cement. The amount of cement is quantified by the bulk density of foam concrete. Generally, more pure cement foam concrete is used, and the bulk density mainly comes from cement. However, many places have now begun to add auxiliary materials such as light aggregates to improve product performance.

3. Formula

The formula of cement foam concrete is ever-changing and cannot be exactly the same. The truly applicable formula should be designed based on the mix ratio design method and the specific conditions of each, and no formula should be copied. But for everyone in formula design or...As a reference during production, here are several cement foam concrete formulas (dosage per cubic meter).

1. Formula of cement foam concrete with a density of 800kg/m3

① Ordinary Portland cement (Grade 42.5) 600kg

Fly ash (Grade 1) 80kg

River sand 120kg

Polycarboxylic acid superplasticizer 6kg

Coagulant C5 12kg

Slurry stability (5% liquid) 30kg

Appropriate amount of foam

Appropriate amount of activated water

② Ordinary Portland cement (grade 42.5) 500kg

Slag powder (Specific surface area 400m2/kg) 200kg

River sand 100kg

FND high-efficiency water reducing agent 5kg

Coagulant C5 10kg

Slurry pouring stabilizer (7% liquid agent) 15kg

Appropriate amount of foam

Appropriate amount of active water

2. Foam concrete formula with density 650kg/m3

① Ordinary Portland cement (Grade 42.5) 585kg

Fly ash (Grade 1) 65kg

Polycarboxylic acid superplasticizer 5kg

Coagulant C5 13kg

Slurry stability (5% liquid) 30kg

Appropriate amount of foam

Appropriate amount of active water

② Double fast Portland cement (grade 42.5) 550kg

silica fume 90kg

waste polystyrene foam particles 10kg

polymer 3kg

Slurry stabilizer (5% liquid agent) 30kg

Appropriate amount of foam

Appropriate amount of activated water

3. Foam concrete formula with a density of 500kg/m3

① Ordinary Portland cement (grade 42.5) 400kg

Finely ground slag powder (specific surface area 450m2/kg) 100kg

Slag activated coagulant F- 11 2kg

Slurry stabilizer (4% liquid) 25kg

Appropriate amount of foam

Appropriate amount of active water

② Rapid hardening silicon Salt salt cement (42.5 grade) 350kg

First or second grade fly ash 120kg

Lime 20kg

Gypsum 6kg

Powder Coal ash activator F-12 3kg

Polymer 3kg

Slurry stabilizer (5% liquid) 20kg

Appropriate amount of foam

Appropriate amount of active water</p