Will adding calcium formate as an admixture cause loss of concrete? The use of cement and admixtures in construction is basic, so a lot of admixtures will be added to concrete, but the adaptability of some high-efficiency water-reducing agents is affected by a variety of factors. The complex problems caused by the impact sometimes cannot be solved by relying on compound solutions or adjusting the concrete mix ratio. They can only be solved by changing the cement brand or manufacturer, and chemically synthesizing new polymer additives. Now, new early-strength setting accelerators are added Will calcium formate cause concrete loss?
01 Loss caused by water reduction rate of admixture
It is generally difficult to determine the loss caused by water reduction rate. The difficulty lies in the loss caused by water reduction rate. The losses are similar to the losses caused by retardation and other factors. Some people say that it can be adjusted by increasing the dosage of admixtures. In fact, this is not the case, because increasing the dosage will cause many disadvantages to concrete and affect the normal use and use of concrete. The mold removal time and many other influences. For example, some small material components will have a superimposed effect by increasing the dosage during large water reduction, which will cause slump loss. Although the slump loss is solved, it will also cause concrete leakage, segregation, etc. There are many problems.
This situation often occurs in high-speed rail construction and various construction sites. Because the dosage at construction sites is generally low, the dosage is not considered to increase greatly during compounding, or the dosage is controlled at Within a very narrow range, sometimes small fluctuations in the gradation of sand and gravel can cause insufficient water reduction or excessive water reduction, resulting in losses. In this case, general construction sites can use mixing or Methods such as increasing water use can temporarily solve the loss, but the impact on strength is immeasurable, especially the surface of the concrete after the formwork is removed, causing sand lines or pockmarks and other various impacts.
Relatively speaking, It is said that calcium formate has a wider application range and more stable performance, because the formic acid in calcium formate is a weak acid and there is a hydrolysis process in the aqueous solution, so the aqueous solution of calcium formate should be weakly alkaline and can also be used in reinforced concrete. Use industrial calcium formate to achieve early strength and initial setting effects.
02 Loss caused by retardant materials
When the admixtures and proportions are confirmed to be reasonable in all aspects, Many technicians need to ensure the loss of concrete for an hour or more according to the requirements of the construction site. The first thing they consider is to lift the retardant materials they often use to ensure the loss. Sometimes, if you use too little, you will not be able to protect it, and if you use too much, it will not last. Causes serious bleeding or even instantaneous damage.
The phenomenon of loss caused by retarded concrete generally shows that the concrete flow pattern is slightly lower and the slump is significantly reduced. This does not exclude the possibility of observing other details of the concrete. phenomenon to determine whether it is caused by retarding materials. It is recommended not to blindly use or abuse some retarding materials without data to solve the problem of retarding. Even after the solution is solved through consultation, it is necessary to determine whether it is through experimental data as soon as possible. Reasonable, and find a familiar retarding material to solve the problem. Reasonable use of retarding is good for health, improper use can also cause indigestion.
It is of great significance in construction. The initial setting time should not be too short, and the final setting time should not be too short. The setting time should not be too long. The final setting time is the time from when the cement is mixed with water to when the cement slurry completely loses its plasticity and begins to produce strength. Especially in winter construction, avoid too slow setting speed at low temperatures. Many projects are In mortars and various concretes, industrial calcium formate is used to speed up the hardening of cement, shorten the setting time, and increase the strength of cement products as soon as possible. This is an important advantage. Therefore, industrial calcium formate will also be used in summer. , only the amount used has changed. The amount of industrial calcium formate in cement mortar and concrete can be proportioned according to the amount of cement used in construction.
03 Losses caused by improper air entrainment
Except for the air-entraining water-reducing admixture, too much or too little air entrainment in the admixture compound will cause excessive concrete losses. Although the air-entraining admixture occupies a small proportion or even no use, it has It plays a very important role. In many projects, there are customized standard requirements for air entrainment.
Calcium formate can significantly improve the early strength of concrete, and the 24-hour strength can reach more than 90% of the design strength. The 24-hour compressive strength ratio is 254%, the 36-hour strength can reach more than 100% of the design strength, and the strength is significantly improved in the later period. The 28-day strength can reach more than 120% of the design strength, which can greatly shorten the construction period. Therefore, adding Calcium formate will not cause concrete loss and can effectively improve early strength
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