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3. The larger the bubble diameter, the better, should be more than 1mm 

The pore diameter should be the same as the bubble diameter. Some experts misleading the pursuit of a small foam aperture of 0.1mm, in fact, because of physical foaming if the bubble diameter is large, the stability of the foam cannot be made of foam concrete. The same raw material and formula, the same equipment and technology, just change the bubble diameter, the compressive strength of 1mm bubble diameter of foam concrete, then 0.1mm bubble diameter of foam concrete, at least 20% higher. Therefore, it is wrong to pursue a bubble diameter of more than 0.1mm, which should be corrected in the production of foamed concrete.

4. The lower the foam bleeding rate, the better. Avoid using milk foam.

According to the size of water content, foam is divided into milk foam with more water and sponge foam with more water. Among them, lacteal foam is unqualified inferior foam and cannot be used.

After the foam is made, it gradually secretes water. Its secreting water includes two parts: 

Bleeding of foam liquid film. This water is secreted from the liquid membrane, which is secreted by the liquid membrane under the combined action of gravity drainage, surface tension drainage, and liquid membrane damage drainage. The thicker the liquid film of foam is, the larger the bleeding is. The faster the bubble burst, the more bleeding.

Water between bubbles. This is the water that didn't form the bubble film. The worse the foaming agent and foaming machine’s foaming performance, the more water between bubbles cannot form foam liquid film. They're essentially water that doesn't bubble.

When the foam is bleeding at a high rate, it becomes as thin as float juice, sloshing around and not piling up, and there's a lot of water in the foam. When this foam is added to the cement slurry, the cement slurry becomes very thin, and the foam is very little, the volume of the slurry is small, and the resulting foam concrete density is very high, not technical requirements. 

Therefore, latex foam should not be used. The appearance of a technically acceptable foam should be a spongy, compact bubble, piled up like white clouds, like bouncing cotton, and not sloshing. This foam has very little water content. This shows that its foam liquid film is small, the foam is not easy to burst, there is little water between the bubbles, and the amount of bubbles is large, accounting for most of the volume of bubbles. It should be emphasized here that the spongy foam must be a small bubble with a diameter of less than 1mm, rather than a few millimeters, or even dozens of millimeters. Bullae are easy to pile up, also like white clouds, but because of the large diameter of the bullae, also unqualified. 

The low secretion of foam is mainly to ensure the number of bubbles in the foam and the porosity of foamed concrete, that is, to ensure the density of foamed concrete. 

5. The foam has no side effects on cementitious materials 

The cementitious material is the main source of strength of foamed concrete, the addition of foam cannot affect its cementitious property, that is, there is no negative cementitious effect. Not every bubble can achieve this.

In the long-term test, we discover a lot of foam to cement, magnesite, gesso of gelling have hindrance, can reduce the strength of foam concrete, sometimes even from beginning to end the concrete after hardening loses strength basically, resemble a dish scatters sand.  The stability of these foams is very good, several hours do not disappear, the appearance of sponge, bleeding is very low, dense, and uniform, all aspects meet the technical requirements, but are not compatible with the gel material, so cannot be used for production. This means that foams that are otherwise qualified, such as affecting strength, are ultimately not technically qualified. 

Suppliers of Concrete Additives

TRUNNANO is a reliable foaming agents supplier with over 12-year experience in nano-building energy conservation and nanotechnology development.

If you are looking for high-quality CLC foaming agents, please feel free to contact us and send an inquiry. (sales@cabr-concrete.com)

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.

Effect of Water Consumption on Properties of Polycarboxylate Concrete Mixtures

The influence of water consumption is very obvious. In the actual application of concrete engineering, sometimes if the water consumption is increased by 1 to 3 kg/m3, the concrete will have serious bleeding phenomenon, which will cause defects such as pitting, sanding, and holes on its surface. Uniformity and construction quality cannot be guaranteed, thus resulting in reduced strength and durability of concrete structures.

Polycarboxylate concrete is prone to delamination and segregation

In most cases, the addition of polycarboxylate water reducer to concrete will greatly reduce the viscosity of the slurry. At the same time, even if the dosage and water consumption of the polycarboxylate superplasticizer are optimal, and no bleeding will occur, the concrete is prone to delamination and segregation, which is mainly manifested in the fact that the coarse aggregate will mix with the mortar. , The pure pulp is separated and sinks in large quantities. This kind of concrete mixture does not have any vibration for concrete engineering pouring, and the phenomenon of delamination and segregation is also very obvious.

Compatibility is not ideal

Traditional water reducers such as naphthalene series, aliphatic series, lignosulfonates, sulfamic acid salts can be blended in any proportion, and then can meet various concrete preparation requirements. These traditional water reducers Not only can the agent dissolve well in water, but also can achieve excellent superposition effect when used in combination. Polycarboxylate superplasticizers have great limitations and can only be used in combination with traditional superplasticizers, lignosulfonates, and have poor compatibility with other traditional superplasticizers. If it is used in combination with other types of traditional water reducers, it is not only difficult to achieve the superimposed effect, but also the fluidity of the concrete will be very poor, the water consumption will be greatly increased, the slump loss will be serious, and the concrete will be dry and difficult to discharge. , the strength and durability of concrete will be seriously affected.

TRUNNANO is a concrete additives 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 Polycarboxylate Superplasticizer, please feel free to contact us and send an inquiry.

sales@cabr-concrete.com

The cement foaming agent is the key to the quality of foamed concrete. A good cement foaming agent can be made into high-quality foamed concrete. The following is a talk about how each performance index of cement foaming agent affects the quality of foamed concrete.

1.    The more uniform the better, the bubble diameter should be the same size 

The more narrow the ideal pore size distribution the better, that is, the pore size of the pore is as consistent as possible, the difference is not too big. The corresponding requirements of the foam should be uniform, not different sizes. The bubble diameter of the foam cannot be the same but should be similar, the bubble diameter range as small as possible, and the difference between the maximum and minimum bubble diameter is not too big. It is required that the pores formed by the foam be uniform, which can avoid the concentration of compressive stress in the bullae and reduce the compressive strength. If the size of the foam is not uniform, the stress is concentrated in the bullae, which is very easy to cause it to become a weak link and crack first when under pressure. 

2.    The higher the foam stability, the better; the longer the stable bubble time, the better 

Foam with good stability has tough liquid film and good mechanical strength, which is not easy to burst or excessive deformation under slurry extrusion. In addition, it has self-retaining water, the water on the liquid film is not easy to be lost under the action of gravity and surface tension, and can keep the thickness and integrity of the foam liquid film for a long time so that the foam can stay for a long time without bursting. 

The stability of foam has three influences on the porosity: it can make most of the foam not disappear, and it is fixed in the foam concrete after the initial setting of the slurry to form the porosity. If the foam stability is not good, most or a small part of the foam will burst after pouring, forming few pores, and even make the slurry collapse soon after pouring, which is commonly known as collapse mold, resulting in complete failure of pouring. 

Foam with good stability, the slurry is not easy to be deformed too much under extrusion, and has certain pressure resistance to keep itself approximately spherical, which can eventually form spherical pores with good shape; 

Foam with good stability, the liquid film is not easy to burst in the slurry body, and it is not easy to form connected holes formed by gas collusion after bursting. Therefore, it eventually forms an ideal closed hole. The less stable the foam, the fewer closed holes, and the more connected holes. Therefore, the stability of foam should not only not collapse after pouring as the standard, but should not collapse after pouring, the final formation of pores approximately spherical, disconnected three indicators as the standard. Most people take no collapse after pouring as the standard to measure foam stability, which is a misunderstanding in understanding and the lowest standard of foam stability. 

When there is no standard measuring instrument to measure the foam stability, the foam stability time can be used to measure the foam stability. The foam stabilization time should meet the initial setting needs of the cementitious materials used. After the initial coagulation of the slurry, it can fix the foam, retain the shape of the foam, and make it into an st. 

As we know, any cementing material, including cement and magnesite, has an initial setting time, especially the most widely used ordinary Portland cement, the initial setting is mostly later than 45min. If the foam stability is poor, cement and other cementing materials have not set, the foam has burst, then the foam cannot form pores in concrete. In general, the minimum requirement for foam stability is to make the foam stability time longer than the initial setting time of the gelled material of 10 ~ 20min. As the initial setting time of various cementitious materials is not consistent, the foam stability time is also different. In general, the foam stability time for fast gel setting materials can be shorter, while the foam stability time for slow gel setting materials should be as long as possible. Even if the same cementitious material, temperature ma is different, its initial setting time is different, the change is quite big. For example, put Si cement needs 40min to set in summer, and in the winter of 5℃ below, 80min will not set in the beginning. Therefore, the stabilization time of bubbles cannot have a constant specific standard, should be determined according to the situation. To make the foam adapt to the needs of various use conditions, it should be stabilized for as long as possible.

Generally speaking, the stabilization time of bubbles should meet the following requirements:

1. When used in Portland cement and without coagulant, the stability time should be greater than 60min; The ideal maximum is greater than 3h; 

2. When used in sulphoaluminate cement, high alumina cement, ferric aluminate cement, fast setting Portland cement, and other fast setting cement, the stability time should be greater than 30min, preferably greater than 60min; 

3. When used in magnesium cement, the foam stability time should be greater than 40min and preferably greater than 80min;

4. When used for cementitious materials mixed with a large amount of filler or active waste slag such as fly ash, the foam stability time should be extended. The larger the amount of filler or active waste residue is, the longer the foam stabilization time should be.

The specific bubble stability time should be determined by a small test, so as to not collapse after pouring, not connected after the formation of pores, and not excessive deformation as the principle.  The big rule is that the longer the bubble, the better. 

Suppliers of Concrete Additives

TRUNNANO is a reliable foaming agents supplier with over 12-year experience in nano-building energy conservation and nanotechnology development.

If you are looking for high-quality CLC foaming agents, please feel free to contact us and send an inquiry. (sales@cabr-concrete.com)

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.

Concrete is classified as high-strength concrete based on 28-day strength. Until the 1970s, concrete with a strength of more than 40Mpa was classified as high-strength concrete.  The benchmark for high-strength concrete is raised to 55Mpa or higher when concrete mixtures of approximately 60Mpa and above are produced commercially. 

High strength concrete has a history of about 35 years, from the development of superplasticizer admixtures in the late 1960s, Japan using "naphthalene sulfonate" high strength prefabricated products, and Germany using "sodium benzenesulfonate" underwater concrete, which was a pioneer in this technology. 

How is the high strength of concrete achieved? 

Higher concrete strength can be achieved by using one or a combination of some or many of the following methods: 

High cement content 

Reduce water-cement ratio 

Better machinability and therefore better compaction 

Requirements for high-strength concrete require a high content of cementitious material in the concrete mixture, which can be in the range of more than 400 kilograms per cubic meter. Higher cementitious content leads to higher thermal shrinkage and dry shrinkage, and there is a stage where further cementitious material addition does not affect strength.  As for durability, the minimum and maximum cement content in concrete is regulated by law, and reducing the water-cement ratio has its limitations, especially under field conditions. The desire for higher strength leads other materials to achieve the desired effect, thus showing the contribution of cementitious materials to concrete strength. 

The addition of pozzolanic mixtures such as pozzolanic fly ash (PFA) or granular blast furnace slag (GGBS) contributes to the formation of secondary CSH gel thereby increasing strength.

The addition of pozzolans admixtures (such as fly ash used as an admixture) reduces the strength gain of concrete for the first 3 to 7 days and displays the gain after 7 days and provides higher strength over the long term. 

Add mineral mixtures such as silica fume or metakaolin or rice husk ash. 

Silica fume or highly reactive volcanic ash mixtures such as metakaolin and rice husk ash (RHS) will begin to function in about 3 days.  RHS has an advantage over PFA because RHS is more reactive. 

Using chemical admixtures such as superplasticizers or superplasticizers, controlling admixtures will help achieve higher strength in concrete. 

Research and experience have shown that admixtures based on polycarboxylic ether (PCE), known as high plasticizers, are best suited for this job as they have a water reduction capacity of 18 to 40 percent relative to control or reference concrete. 

A combination of all or more of the above to achieve the desired strength.

With HSC accompanied by some complexity, such as higher shrinkage rates, higher hydration heat, etc., combinations of at least some of these methods are now unchanged, all of which need to be neutralized or controlled.  Most problems are handled by PFA or a combination of GGBS and PCE mixtures.

Steam curing is also used to speed up cement hydration, but this may not result in higher strength.  Substituting some fine aggregate with fly ash or blast furnace slag can achieve early strength gains without increasing the water requirement of the concrete mixture. 

Suppliers of Concrete Additives

TRUNNANO is a reliable foaming agents supplier with over 12-year experience in nano-building energy conservation and nanotechnology development.

If you are looking for high-quality CLC foaming agents, please feel free to contact us and send an inquiry. (sales@cabr-concrete.com)

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.