Foam concrete is a kind of concrete with lightweight and has ideal strength. Because of the hollow structure in foam concrete, it has the function of absorbing heat and isolating sound.
The density of foamed concrete is 300-1200 kg/m3, and the thermal conductivity is between 0.08-0.3W/ (m ·K).
Foam concrete is widely used in CLC blocks, lightweight partition panels, roof insulation, floor cushion construction, floor heating backfilling, and other occasions.
At the same time, foam concrete is also a good sound absorption material, which can be used in highway sound insulation boards, sound absorption boards, and other fields.
Generally speaking, foam concrete is a kind of building material with multi-function, environmental protection, and economy, which has a wide application prospect.
How to add micro silica fume
There is no significant difference in the construction method between micro silica powder concrete and ordinary concrete, but it is necessary to organize and vibrate well during construction. The early strength performance of micro silica powder concrete can advance the final setting time, and special attention should be paid when plastering. Adding micro silica powder at the same time can improve the viscosity of concrete and significantly reduce bleeding, making the plastering slightly difficult.
1.
Generally, it is 5-10% of the amount of cementitious material. The addition methods of micro silicon powder can be divided into internal and external mixing,
1) Internal mixing: With the same amount of water added, 1 part of silica fume can replace 3-5 parts of cement (weight) and maintain the compressive strength of the concrete while improving other properties.
2) External addition: The cement dosage remains unchanged, but adding micro silica powder significantly improves the strength and other properties of concrete. When micro silica powder is added to concrete, there is a certain slump loss. This should be noted during the mix ratio test.
2.
Doping and usage method of micro silicon powder for building concrete
When using micro silica powder to prepare concrete, the weight ratio to the cementitious material is generally:
1) High performance concrete: 5-10%;
2) Hydraulic concrete: 5-10%
3) Sprayed concrete: 5-10%;
4) Pump aid: 2-3%;
5) Wear resistant industrial floor: 6-8%;
6) Polymer mortar and insulation mortar: 10-15%,
7) Unshaped refractory casting material: 6-8%. Please select a reasonable and economical dosage through experiments based on actual needs before use.
3.
The construction mix proportion of micro silicon powder concrete and pouring materials shall be determined by the laboratory. Strictly follow the mix ratio for construction. In the mixing of micro silica powder concrete, the micro silica powder should be added to the mixer immediately after the aggregate is fed.
There are two ways to add:
Add aggregates, then add micro silica powder and cement for dry mixing, and then add water and other admixtures.
Add coarse aggregate+75% water+micro silica powder+50% fine aggregate, mix for 15-30 seconds, then add cement+additives+50% fine aggregate+25% water, and mix until uniform. The mixing time is extended by 20-25% or 50-60 seconds compared to ordinary concrete. Do not add silica fume to the mixed concrete.
Cooperation ratio
If foam concrete is prepared only by using cement, the higher the strength of the cement used, the greater the strength of foam concrete. Generally, a mixture of silicon powder, fly ash, sand, and slag is added together. The participation of the mixed materials will lead to a decrease in the early strength of foamed concrete, but it has little effect on the later strength. If stimulators are introduced together, the loss of early strength can also be reduced to some extent. When sand is used as fine aggregate, the strength of foam concrete will not be reduced in general, but it has great benefits for volume reduction and stability.
Water cement ratio
Only by analyzing the internal structure changes of foam concrete, the increase of water cement ratio will inevitably lead to the reduction of strength. Many experiments have proved that when the water cement ratio is added within a certain range, the strength will not only decrease, but also increase, because the preparation of foamed concrete has a foam mixing process. Suppose foam needs to be evenly distributed in the system. In that case, the slurry needs to have excellent fluidity, and in order to ensure excellent fluidity, a higher water cement ratio is required. However, under the condition of low water cement ratio, taking appropriate measures can also ensure excellent fluidity of cement slurry and then make high-strength foam concrete.
Maintenance conditions
Maintenance conditions have a serious impact on the strength and strength development of foam concrete. The water ash content of foam concrete is relatively high, so early maintenance should be strengthened to avoid strength reduction and cracking due to rapid evaporation of water. When the maintenance temperature rises, the hydration rate of cement accelerates, and foam concrete develops rapidly in the early stage, but the strength of concrete has a certain negative impact.
Additives
Admixtures related to foam concrete mainly include foaming agent, water reducing agent and additive initiator. As mentioned above, foaming agents have a greater impact on foamed concrete. It is necessary to choose foaming agents that have few side effects on the system, strong foaming ability, and high foaming strength. The main function of initiator is to make foam concrete deteriorate. Early intensity decline can reduce the fluctuation of the decline, but it also reduces the intensity of the outcome. The water reducer can make the system mix foam and slurry evenly at a lower water cement ratio.
Uniformity control
The control factors affecting the uniformity of foam cement slurry are mainly if the design parameters of the static mixer are reasonable or not, especially its length, the number, angle and layout of internal mixing parts. These parameters have an optimal match. Whether the match is unreasonable, the slurry will be uneven. Different manufacturers have different designs, and the core is whether they can all be reasonable and whether they have been tested and optimized before design.
Density control
The factor controlling the density of foam cement slurry is mainly the proportion of foam slurry entering the static mixer, that is, whether the proportion of foam and cement slurry is reasonable and accurate. The greater the bubble-to-paste ratio, the lighter the paste. If the ratio of the two cannot be precisely controlled, it will cause density fluctuations. The key factor is whether the equipment has designed and installed a foam and slurry control mechanism, and the degree of automation of the mechanism. At present, there is no control mechanism installed on some equipment, and the density is not easy to control. How to realize its automatic control, this is the core technology.
Suppliers of foam concrete additives
Luoyang Tongrun Info Technology Co., Ltd. (cabr-concrete.com) is a reliable and high-quality material supplier and manufacturer of foam concrete additives. It has more than 12 years of experience providing ultra-high quality chemicals and nanotechnology materials, including Water reducer, nitride powder, graphite powder, sulfide powder, and 3D printing powder. It accepts payment via Credit Card, T/T, West Union, and Paypal. TRUNNANO will ship the goods to customers overseas through FedEx, DHL, by air, or by sea. If you are looking for high-quality concrete additives, please feel free to contact and send an inquiry. (sales@cabr-concrete.com).
Overall, cement foaming agent influence many performance indicators such as cement strength, water absorption, pouring height, density, and thermal conductivity.
Cement foaming agent is a main material for foaming cement, and selecting the right cement foaming agent is depended on whether to produce foaming. There are many kinds of cement foaming agents on the market now, and their prices also vary much. Many people are blind in selecting foaming agents or choose whichever one is cheaper. Actually, the cost of cement foaming agent in foam concrete is the lowest. If we choose cement foaming agent by price alone, we think it is not advisable.
Nowadays, cement foaming agents on the market are generally divided into synthetic cement foaming agents, animal and plant protein cement foaming agents, composite cement foaming agents, and rosin soap cement foaming agents. Each of these types of foaming agents has its own advantages and disadvantages. Among them, synthetic cement foaming agents are widely used due to their low price, especially in the roof insulation market. Transparent and low-cost foaming agents are commonly seen as this type of foaming agent. The main reason for this is that the roof insulation market does not emphasize quality. In the words of the construction unit itself, "roof insulation is just a tofu residue project." However, if this continues, the market will eventually fail.
Animal protein cement foaming agent has the advantage of good foam stability and closed cell rate. The foaming power and stability of plant-based cement foaming agents are relatively balanced.
In many people's minds, the idea that cement foaming agents are only foaming and reducing density is very one-sided. Cement foaming agents are actually related to the strength, thermal conductivity, solidification rate, water absorption, pouring height and other properties of foamed cement. Therefore, when selecting cement foaming agents, one should not solely consider their price, but rather the overall cost. The cost of cement in foamed cement occupied more. How to reduce the cost of cement is the main problem of reducing the cost of foamed cement. How to reduce the cost of cement can be achieved by increasing its strength and reducing the amount of cement used. The strength of foamed cement with the same density has been improved. If the strength remains unchanged, the cement dosage can be reduced, and the density can also reach the original strength. For example, the strength of the original 400 density foam concrete is 0.6 mpa, but the strength can be increased to 350 to 0.6 mpa. This saves 50 kg of cement, the strength is reached, and the thermal insulation performance is also improved. One of the best ways is to choose a good cement foaming agent.
The strength of foam cement is a key indicator. Foam cement is an artificial stone material that has been foamed, and its density is low. The strength naturally decreases with it, and the low density strength decreases even more. How to improve the strength of foamed cement has become a key factor in improving its performance. Choosing a good quality cement foaming agent can effectively enhance the strength of foamed cement. A great cement foaming agent can form bright closed pores in the foaming cement, greatly improving the compactness of the foam wall and thus enhancing its strength. Good cement foaming agents can be used at low water cement ratios, and the lower the water cement ratio, the higher the strength. Up to now, many cement foaming agents on the market can only be applied under high water cement ratio, which is the main reason why many construction teams use high water cement ratio for construction. It looks like porridge, and it is also said that this is "self leveling", which sacrifices the strength of foaming cement, and has become a "bean decay project". The compatibility between cement foaming agent and cement also influences its strength. If the foaming agent does not match with cement, the most common problem is that the foaming agent becomes the isolation layer of cement, forming a "false setting" phenomenon. In fact, it does not solidify, forming an isolation layer that prevents the cement from fully reacting, resulting in the product being particularly "crisp" and lacking in strength.
Water absorption rate
At present, many foamed cement products on the market have very high water absorption, some up to 50%. The reason is that the foamed cement has low closed cell rate, and through holes are formed due to channeling and poor stability of cement foaming agent foam. This is all due to the low closure rate of cement foaming agents, so a good quality cement foaming agent can make the water absorption rate of foamed cement products low.
Pouring height
The pouring height of foaming cement is directly related to the foam stability of cement foaming agent. The higher the pouring height is, the higher the stability of cement foaming agent foam is, and vice versa. The higher the pouring height is, the greater the pressure of slurry on foam will be. If the stability of foam is poor, it will collapse.
Density
The key to control the density of foamed cement is the amount of foam added, so the direct factor affecting the density is the cement foaming agent. The more stable the cement foaming agent foam is, the better the density can be controlled, and the more low-density foamed cement can be produced. On the contrary, if the stability of cement foaming agent is not suitable, a density of 400 and pour it into 500 kilograms can possibly be designed . It is also possible that the density is different between the top and bottom, which is uneven in density. This problem is more obvious in wall pouring.
Thermal conductivity
The most direct influencing factor on thermal conductivity is the density of foamed cement, and the key factor for density control is the cement foaming agent. In order to correct misconceptions in the industry, it is widely believed that thermal conductivity is directly related to porosity. In fact, according to our inspection of foam concrete test blocks with different closed cell rates and densities of 200kg/m3, it is found that the thermal conductivity of high closed cell rate is 0.059 compared with low closed cell rate.
TRUNNANO is a cement foaming agent supplier with over 12 years experience in nano-building energy conservation and nanotechnology development. We accept payment via Credit Card, T/T, West Union and Paypal. Trunnano will ship the goods to customers overseas through FedEx, DHL, by air, or by sea. If you are looking for high quality cement foaming agent, please feel free to contact and send an inquiry.
Foam concrete is a kind of lightweight, multi-functional, environment-friendly heat preservation and energy-saving material. Foaming agent, cement, fly ash, foam stabilizing agent and other additives are the main materials of foam concrete.
Raw materials of foam concrete include cement, foaming agent, admixtures, etc. The quality and performance of these raw materials directly affect the quality of foam concrete. For example, the strength, stability and durability of cement, the foaming power, stability and storage period of foaming agent, and the workability and activity of admixtures will affect the quality of foam concrete.
The raw material ratio and production process of foam concrete are also important factors affecting its quality. Reasonable selection and strict control of production process parameters such as the proportion of different raw materials, foaming time and pouring pressure can ensure that foam concrete has good performance and stability.
Grain size and uniformity of raw materials
Grain size and uniformity of raw materials will also affect the quality of foam concrete. Too small or too large particle size, as well as uneven particle size distribution, may cause the strength, density and stability of foam concrete to decline.
Water content and temperature are also factors that affect the quality of foam concrete raw materials. High water content will lead to instability of bubbles in foam concrete, thus affecting its performance. Too high temperature will lead to unstable performance of raw materials, thus affecting the quality of foam concrete.
In order to control the quality of raw materials for foam concrete, measures should be taken from the following aspects:
Choosing high-quality foaming agent, cement, admixtures and other raw materials is the major premise to ensure the quality of foam concrete. When selecting raw materials, reasonable selection and testing should be carried out according to engineering needs to ensure that the strength, stability, durability, and other aspects of the raw materials meet the requirements.
Production technology is one of the key factors affecting the quality of foam concrete. In the production process, the raw material feeding ratio, foaming time, pouring pressure and other parameters should be strictly controlled to ensure that the density, strength, stability and other indicators of the produced foam concrete meet the design requirements.
Strict inspection should be conducted on the purchased raw materials to ensure that the quality of the purchased raw materials meets the requirements. All raw materials entering the factory must have quality inspection reports, laboratory test reports for cement and active admixtures, and qualification certificates for admixtures. At the same time, measures such as moisture-proof, sun protection, and fire prevention should be taken for the storage of raw materials to avoid problems such as moisture and deterioration.
If possible, the activity of cement and active admixtures should be tested to obtain the activity index. All raw materials, especially cement, admixtures, foaming agents, and foaming agents, cannot be used as ingredients in the event of failure or decreased activity. Especially cement and other cementitious materials, if there are clumps or clumps, they must not be used again. Some people sieve out the clumped cement and continue to use it. This is very wrong because it can easily lead to mold collapse and a decrease in product strength. If used, only 1% new cement can be replaced at a time.
After three months of storage (in bags), the activity of cement decreases and it is not allowed to be used. After half a year of storage of hydrogen peroxide, a foaming test should be conducted. If the foaming performance decreases, it should not be used.
In addition, fly ash shall not be used for wet ash discharge. If used, it should be dried and ground. Do not use the original wet ash discharge. On the other hand, ingredient water should be tested for no side effects before use and can only be used when there are no side effects. Wherever possible, trace components of water should be tested and at least the pH value should be determined.
To sum up, controlling the quality of foam concrete raw materials is an important part of ensuring the quality of construction projects. In practical application, comprehensive control should be carried out from the aspects of selecting appropriate raw materials, improving production technology, strengthening the inspection and storage of raw materials, etc. to ensure that the quality of foam concrete reaches the best level. Only in this way can we provide safe and reliable guarantees for construction projects and promote the sustainable development of the construction industry.
TRUNNANO is a supplier of concrete foam agent with over 12 years experience in nano-building energy conservation and nanotechnology development. It accepts payment via Credit Card, T/T, West Union and Paypal. Trunnano will ship the goods to customers overseas through FedEx, DHL, by air, or by sea. If you are looking for high-quality concrete additives, please feel free to contact us and send an inquiry. (sales@cabr-concrete.com).
There are two main production methods of foam concrete: one is physical foaming, the other is chemical foaming. We may use TR30 CLC Foaming Machine Concrete Foam Generator.
Physical foaming refers to introducing air, nitrogen, hydrogen, carbon dioxide or oxygen into the slurry formed by cement, cementitious materials, foam stabilizer and water by mechanical method to form a relatively stable slurry system. The stability time of the slurry system should be greater than the initial setting time of the cement. For the physical foaming of foamed concrete, it is generally used to make foamed concrete by introducing air into the cement foaming machine with cement foaming agent and mixing it with the paddle body.
Physical foaming technology is widely used in the fields of floor heating, terrace, roof slope, precast slab and so on. In addition to good foam stabilizer, the key technology is the structural design of foam generator. In the formulation design of the foam stabilizer, the interaction with the foaming agent is not considered, so the selection freedom is large. In terms of equipment, an air compressor and foam generator are used more than the chemical foaming process.
Chemical foaming is to mix the substances (foaming agent) that can react chemically and produce gas together with cementitious materials, foam stabilizers and water, and then pour them into shape. The temperature is controlled to make the foaming agent react to produce bubbles. The best reaction state is that there is almost no reaction during the mixing molding, and the reaction is gradually completed after molding and before the initial setting of cement. The principle of chemical foaming of foam concrete is the same as that of steamed bread. Aluminum powder and hydrogen peroxide are the most common foaming agents in the market.
The machinery used in the chemical foaming process is relatively simple. Since the foaming agent of the cement slurry continues to produce bubbles after pouring and before initial setting, it has the effect of expansion, so the chemical foaming process is mostly used for filling, plugging, reinforcement and other occasions, and can also be used in the field of precast slabs.
Types of foaming agents
Ø Polymer Cellular Lightweight Concrete Foaming Agent
l Different principles
Chemical foaming is to generate gas through chemical reaction to form bubbles inside the concrete mixture, while the physical foaming process is to use surfactant to reduce the surface tension of water, so that the water film can cover the air to form bubbles under the action of the foam maker, and the bubbles are introduced into the concrete mixture by the foam mixer.
l Different processes
The chemical foaming agent mixed into the concrete mixture is the chemical foaming agent, which is mixed first and then foamed; However, the bubble aggregate (foam) mixed into the concrete mixture by the physical foaming process is made first and then mixed.
l Different slurry changes
After adding foaming agent, the volume of concrete mixture used for chemical foaming will gradually expand and increase with the beginning of foaming; However, after the foam is mixed into the concrete mixture, the volume of the physical foam making process will reach the maximum, and will not expand or increase, sometimes it will shrink.
l Different hole shapes
The pores formed by physical foaming are small, and it is difficult to form uniform large pores of more than 5mm. Chemical foaming can form both fine pores and large pores of 3-10mm.
Requirements of the Concrete Chemical Foaming for Its Mixing Equipment
According to the characteristics of chemical foaming, ordinary concrete mixers or mortar mixers are definitely not acceptable. Chemical foaming has some special requirements for mixers that are different from ordinary concrete or ordinary mortar mixers.
1. High-speed or ultra-high-speed mixing
Because chemical foaming requires high uniformity and has a physical activation effect on the slurry, conventional low-speed mortar mixers or concrete mixers are difficult to achieve. The rotation speed of the conventional mixer is only 20-40r/min, and the rotation speed is too low. It is difficult to achieve high uniformity and physical activation. The rotation speed of the chemical foaming mixer should reach 1400~3000/min in the late stage of mixing (after 2min).
2. With stepless speed change or speed regulation function
If only one mixer is installed in the mixing system, in order to adapt to the different characteristics of the three stages of foamed cement mixing: dry first, then thin, and then thick, the speed of the mixer must first mix the dry material at low speed, then mix the thin slurry at medium high speed, and finally exceed High-speed activation and mixing of blowing agent. In this way, the use of constant speed stirring is not feasible, and it is necessary to adopt stepless variable speed or speed regulating stirring to adapt to the different speed requirements of different stirring stages.
3. The mixer must have the effect of uniformly mixing the upper and lower slurries in a very short time
It must have a strong effect of rapid mixing of the upper and lower slurries because the foaming agent is added later and added to the surface of the slurry. Otherwise the foaming agent floats on the upper part of the slurry, which will cause uneven foaming and excessive density difference.
4. The mixer should be the main vertical type
The horizontal mixer has large thrust and strong resistance to breaking, but it is difficult to achieve high speed. Therefore, horizontal mixing is only suitable for the initial mixing of cement and other solid powder materials with water to help overcome the large resistance of the initial mixing. But it is not suitable for the mixing of slurry in the middle and late stages. The speed of the horizontal mixer is too low and the mixing time is too long. Vertical high speed should be used in the middle and late stages. Only a vertical mixer can achieve high speed or super high speed.
5. Strong anti-blocking and anti-sticking ability, easy to clean
Most of the chemical foamed slurries have the characteristics of early strength and fast hardening, fast coagulation, and the slurry is easy to condense on the wall of the mixing drum and the mixing blades. It is difficult to clean, especially easy to block. Material pipelines and valves. The discharge valve is blocked during summer production, which is the most common production accident in the past two years. Therefore, it should have anti-blocking and anti-sticking function, and easy to clean.
Supplier
TRUNNANO is a foam generator supplier with over 12 years experience in nano-building energy conservation and nanotechnology development. It accepts payment via Credit Card, T/T, West Union and Paypal. Trunnano will ship the goods to customers overseas through FedEx, DHL, by air, or by sea.If you are looking for high quality concrete additive, please feel free to contact and send an inquiry.
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