How to solve the problem that C50 concrete sets too fast?

There are several possible questions:

1. First check the temperature of the cement inside the cement tank. Many cement manufacturers send cement to the mixing station without it being completely cooled, and I have seen the temperature of cement reaching more than 100 degrees.

2.Check the quality of fly ash. Due to the large demand for fly ash in many projects, the supply of fly ash is in short supply, and the quality of fly ash is seriously reduced.

3.Check the suitability of the cement to the admixture.

I think that the quality of fly ash is very likely, and it is recommended to strengthen the supervision of fly ash quality.

I do polycarboxylic acid compounding, and there are many successful examples of C50 on the highway, and it can generally be controlled within 1 hour basically without slump. There is time to communicate!

The loss of concrete collapse is very fast, and the most effective way is to add retarding admixture C50 concrete, which has a high heat of hydration, and a large amount of cement in addition to the high ambient temperature.

C50 concrete, large amount of cement, high heat of hydration, in addition to the high ambient temperature, concrete collapse loss is very fast, the most effective way is to add retarding admixture, increase the initial collapse of concrete.

This is caused by admixtures, you can choose to mix admixtures in stages, add one part first, and then add another part after the scene!! Hope it helps!!

1. Caused by heat of hydration.

2. Add retarder. The concrete that meets the requirements is operated by the commercial concrete company according to the design agreement.

The adaptability of cement and superplasticizer is not good, and there is the use of retarding polycarboxylic acid high-performance superplasticizer.

1' retarder.

2.Cooling. 3.Increase the degree of slump.

Concrete belongs to fine stone concrete, because it is C50, it is recommended that you measure the powder content of fine stone, or increase the amount of coarse sand, reduce the amount of stone, if it is not fine stone concrete, you can choose -20 or 5-25 continuous graded stone according to the construction requirements.

The roll degree is high, there is no need to worry, the addition of polycarboxylic acid superplasticizer is hard, but the fluidity is particularly good. Now the design of pumped concrete is made of polycarboxylate superplasticizer. High roll degree is also one of the good workability. As long as the flow is good, it will be no problem to pump.

C50 concrete is more viscous because of its low water-glue ratio and large amount of cementitious material. To improve liquidity, the following measures can be taken:

Improve the content of Qiaonian high-efficiency superplasticizer and increase fluidity;

If the dosage of high-efficiency superplasticizer is appropriate, and the fluidity of concrete is insufficient, it means that the adaptability of superplasticizer and cement is poor, and the superplasticizer is generally adjusted to increase fluidity;

Mix an appropriate amount of fly ash and slag powder to replace part of the cement, reduce the amount of unilateral cement, and improve workability.

The above measures should be used for construction after indoor test mixing.

Under the condition of ensuring that the mix ratio remains unchanged, adjust the amount of fly ash and mineral powder, too much mineral powder is prone to excessive viscosity, and on this basis, adjust the amount of admixture and cement.

Without affecting the strength, appropriately reduce the admixture, increase the amount of water, increase the fly ash, and reduce the mineral powder.

You have a problem with the mix ratio, and you don't know how to understand it. Stickiness, slump is fine, high roll degree? You look at your mix ratio, the stone is selected with a single gradation of 5-10, so small particle size, your sand rate has reached, and the cement dosage of 485 has reached the design strength of C50 with cement.

The amount of cement used is obviously too high. It's a bit difficult to change the problem if you don't mix the ratio. Water reducers are not a panacea.

If the amount of cement is too much, it is recommended to add an appropriate amount of mixed materials; The comprehensive performance of polycarboxylic acid is not good, and it is recommended to find a manufacturer to adjust.

Reduce the amount of admixture, with some mineral powder and fly ash and other admixtures, the effect of K12 is two-way, in the case of concrete unit cement dosage and slump unchanged, due to the addition of air-entraining agent or air-entraining superplasticizer, on the one hand, can increase the gas content of concrete, on the other hand, can reduce the unit water consumption of concrete, that is, reduce the water-cement ratio, thus will have an impact on its strength. As a result of water reduction, the strength of concrete increases, however, from the point of view of air entrainment, the strength of concrete generally decreases (in most cases). Therefore, the effect of adding air-entraining agent or air-entraining superplasticizer on the strength of concrete is the comprehensive result of the two effects.

The effect of air entrainment on strength can be ignored first, the workability can be adjusted first, and then the effect of air entrainment on strength can be determined through comparative tests.

The strength requirements of C55 concrete are too different from the strength of C35 concrete. If you really get it wrong:

1. First of all, ask for the help of the structural engineer of this drawing, and rectify it according to the design requirements.

2. According to the concrete structure specification, C35 concrete must be removed as soon as possible, the steel skeleton must be retained, and C55 concrete must be re-poured.

It doesn't matter if you can achieve design strength. Otherwise, there is a high probability that the column will be hit again.

A column is the vertical main structural element of a building, supporting the weight of the object above it. In Chinese timber construction, beams and columns are responsible for supporting the weight of the beam frame structure and other parts, such as eaves, and there is often a column base between the main column and the foundation. In addition, there are other smaller columns, which are not placed on the foundation, but on the beam frame to support the weight of the objects above, and then transfer the weight to the main column through the beam frame structure.

For example, the ridge melon column or Shu column is the weight of the eaves that supports part of the beam frame. Most of the pillars in ancient China were made of wood, which belonged to the scope of large wooden work; There are stone pillars in between. In order to be waterproof and moisture-proof, the wooden column is padded with a stone pillar base.

The 25th floor should be fine, and the construction unit and the developer can't know about it.

If they knew, they would have knocked it out from the new pour.

Heavy losses. Prepare in advance for rebound, test blocks, etc.

Pay more attention to the strength of the concrete.

If you want to remedy it, you can only do it again.

There is no way to remedy it, how can such a low-level mistake be made.

Early strength concrete is an admixture that can improve the early strength of concrete. 3-day intensity is meaningless, 7-day intensity is generally more than 70% in the case of standard maintenance (mainly depending on the basis of mold removal and advance measurement), and 28-day intensity should reach 100%. Early strength agent is not an admixture that reaches strength early in the superficial sense, it is only generally to improve the early strength, and it is generally a strength comparison for the first 7 days.

The 7-day strength of the concrete mixed with the early strength agent is higher than that of the unmixed concrete, and the consequence of Hengqi mixed with the early strong agent is to sacrifice the later strength as the cost of the hidden family, and the 28-day strength of the concrete mixed with the early strength agent is generally lower than that of the 28-day strength of the concrete without the additives.

If the concrete strength reaches C50, it should be an industrial building or a bridge, let's talk about the opinion.

I haven't tried the high-temperature steaming upstairs but I've heard a lot, this method is only used under the condition that the strength of the test block is not enough to require the test block, and it is required to be sent for inspection within one or two days, and it will reach the strength of 28 days in one or two days.

The local dialect is steamed in a large pot.

If you want to improve the strength of the test block, first of all, see whether the construction site is a commercial mixture, is not very easy to cheat, can only add more stones, but also use the method of adding cement dry powder later, but the effect is not very good, or pick the part of the slump is small and add a large number of stones to work.

If it's on-site mixing, then it's easy to get.

The supervision and management are strict, and you can move your hands and feet on the batching machine, increase the number of cement feeds, such as 50 to 100 kg per plate, and then the slump of the mixing point is particularly small, so that the supervision generally can't say anything, and then transfer back after sampling.

Supervision and management is not strict, you can consider manual mixing, sometimes manual mixing in accordance with the method of cement sand and gravel 4:6:10, the proportion of cement in actual operation will be further increased, and even reach 1:

1.Nowadays, many construction sites use pumping, and the slump cannot be too small.

The advantage of manual mixing is that the slump can be reduced as much as possible, and a small piece of manual mixing is more thorough than machine mixing, and even the method of manual mixing back and forth 60 times has been used, and finally this small pile of concrete can be drawn.

The test block made by this method can reach C30 in 10 days, and it is not a high temperature in summer.

If you are still not at ease, you can use a bench scale to carefully measure and reduce the ratio by many times, which is also the effect.

But to say 1,000 to 10,000, these methods only improve the strength of concrete, there will be no essential changes, if the laboratory ratio is not good, there is no way, that is to say, how to use the ratio of C10 is not enough.

There is no way to guarantee, if it is a commercial concrete, pick the workability is good, the collapse is small, the car is sampled, and more stones in the concrete are placed. On the second day, after demoulding, use 2 layers of curing blankets for watering and curing under the same conditions. The standard culture test block was taken out for 25 days after entering the standard maintenance room.

Your question is too general, what season is the construction of concrete. Whether it is above ground or underground. The transportation distance of the concrete, the pouring time. To put it simply, the key to the maintenance of concrete is moisturizing and anti-freezing. There are many kinds of moisturizing, there is mulch film winding protection, and there is spraying protective film.