What is the reason for the retardation of concrete? Is too much retardant added?

Experts believe that the abnormal conditions of concrete solidification usually include excessive retarding, rapid setting and false setting. Excessive retarding is at least a very common one, so What are the reasons for excessive retardation of concrete? This is a problem that many construction users are very concerned about. Now we mainly introduce the reasons for excessive retardation:

Excessive water-reducing agent Adding may have a serious negative impact on concrete. Experience shows that if the amount of retardant and concrete antifreeze added to concrete exceeds the limit, the properties of concrete may be seriously reduced. Triethanolamine is a widely used concrete admixture. Many experimental statistics show that if the dosage of triethanolamine exceeds 0.05% of the concrete quality, it will inevitably reduce the compressive strength of concrete products. If the dosage exceeds the standard, the greater the comparison. The more serious it is, the greater the negative impact it will have on concrete. In addition, if sulfate water-reducing agents are added to concrete without measuring the sulfate ion moisture content in the concrete, the sulfate ion moisture content in the concrete may seriously exceed the standard, thereby reducing the quality of concrete products. Performance and compressive strength.

When the water content is high, the compressive strength of the fibrous rough stone is relatively low, and the bonding strength between the rough stones is reduced, resulting in concrete Rebound is reduced. For ready-mixed concrete, the high water content of needle-shaped stones will make the grain shape of the coarse stones not good, thereby reducing the fluidity of the concrete. At the same time, the needle-shaped stones are easy to block in the pipelines, causing blockage of the pump, and even Burst pipe. Therefore, the water content of the needle blades required for concrete pumping is ≤12%, and the requirements for high-toughness concrete are even higher.

Secondly, concrete with too large a fineness will also have an unsatisfactory initial state. The effect will be achieved by increasing the water demand or increasing the amount of water-reducing agent. It is not easy to be too idealistic. This kind of thing is basically consistent with the performance of the pure paste. We can only solve the problem by adapting to the situation: that is, not only adding amine or aliphatic additives that are easy to bleed into the main agent of the water-reducing agent, but also appropriately increasing the amount of sodium gluconate on the premise that the retardation meets the requirements; At the same time, the mortar mix design is designed to allow the concrete to bleed in its initial state. Another switch to polycarboxylate admixtures will also result in significant improvements. In other words, the prerequisite for concrete testing is that the original slump and fluidity expansion must meet the design requirements, otherwise it will be impossible to control the slump damage of concrete.

1. The retarder components in the concrete admixture are excessive, especially when the water content of soft sugar is high;

2. Human factors or equipment failure lead to excessive mixing of concrete admixtures.

3. During the concrete production process, concrete is mistakenly used as coal ash or mineral powder.

4. If the concrete mix ratio is poorly designed and there are too many admixtures, it is very easy to cause excessive mixing when the temperature of the concrete pouring environment is low. The production of retarded setting.

5. Temperature will be affected when making concrete. The temperature is too low, which may cause the problem of excessive retardation of concrete.

6. During the concrete production process, maintenance is not timely, especially when the temperature is too low, maintenance is very late.

7. When the air content of concrete is too large, it may cause the air content of concrete to exceed 8-12%.

8. If the concrete slumps are too large and the concrete separates and bleeds, it will most likely lead to a high ash moisture content on the concrete surface. The condition of concrete with high water-cement ratio.

So what is the reason for excessive retardation of concrete? According to the introduction, I believe that the majority of customers are already aware of this problem. If you have other questions, you are welcome to come to Haobo Intelligence for consultation.

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