Superplasticizer is called the fourth generation of water-reducing agent, according to the materials, it has less content, less water, high slump performance, and adaptability of cement, concrete shrinkage and so on. Thus, for the first time the user the impression that the water-reducing agent than the previous generations water reducer in use more convenient, safe, efficient, but after the application of the last two years I found that the water reducer and other water reduction agent, as there are some limitations, its advantages is only relative, so in many of the problems encountered in production, and even some of the issues that many of us psychologically difficult to accept.

Incompatible with a cement grave, leading to the hair to the site of the concrete mixing station can not properly use a brand name with the seat of Area with cement, QL card P · O42.5R cement, supply of C50 concrete to a construction site, using a polycarboxylic superplasticizer, do concrete mix, we found that the cement content than the other cement superplasticizer slightly, but the actual mixing, the visual factory slump concrete mixture of 200 mm, to the site to the concrete pump When unloading the car, they found the car did not come out of concrete has been unloaded, notice sent to the factory after stirring a bucket of water reducer, visual slump of 170 mm, could meet the pumping requirements, but just dumping 1 cubic meter or so, it is not unloaded out, the car immediately returned to the manufacturer of concrete, adding a lot of water and a small amount of reducing agent, reluctantly discharged, nearly freezing in the mixer.

Reason: did not insist on every batch of concrete before the opening bell to do with the admixture test their adaptability.

Prevention: 1. For each batch of cement in construction before the opening match with a mixture than doing a test.

2. As far as possible to avoid the use of "coal" to do the cement admixture and superplasticizer in preparing the concrete.

Slump concrete mixture abruptly, bleeding, was the site returned to use in a mixing cement in a cement plant P · O32.5R preparation of C30 concrete, slump to the site for the contract calls for 150 mm ± 30 mm, concrete factory , measured 180 mm slump, delivered to the site, the site measured concrete slump was 210 mm, for two consecutive cars be returned concrete, the slump back to the factory certification is still 210 mm, but also bleeding, stratified phenomenon.

Reasons: 1. The adaptability of cement and the water reducer, superplasticizer dosage slightly.

2. Stirring time is not enough, the machine of concrete slump due to short mixing time shown slump slump is not true.

Prevention: 1. Sensitive to the admixture of cement content, admixture content to be appropriate, measurement accuracy is higher.

2. An appropriate extension of mixing time, even if the twin-shaft compulsory mixer, mixing time should not be less than 40 seconds, preferably more than 60 seconds.

Superplasticizer dosage is too large, concrete structure standing on the surface of the bubble too much of a stir for some time been prepared with concrete superplasticizer, the site reflects a sudden one day, found the wall surface of wall form removal bubble too much, and feel bad.

Reasons: 1. Pouring concrete on the day, the site reflects the slump many small, poor mobility, concrete mixing station lab on duty increased admixture content.

2. The site is used to shape steel large formwork, pouring too much time feeding, vibration uneven.

Prevention: 1. Superplasticizer and the same naphthalene superplasticizer has a saturation point, for different kinds of cement, different amount of cement, admixtures in concrete in the saturation point is different. If the admixture content is near its saturation point, can only adjust the amount of paste in concrete or other means to improve the flow of concrete mixture.

2. To strengthen communication with the site, the proposed height of the first feeding, vibration methods operate strictly according to specifications.

Superplasticizer super fly, a large concrete slump, concrete 24 hours before final setting of concrete slab in the structure of a site 15 hours after pouring, the concrete mixing station to reflect some have not solidified, mixing station to send engineers to view, by the increase after temperature treatment, 24 hours before final setting.

Reasons: 1. Superplasticizer dosage larger, add the night temperature is low, slow hydration reaction of concrete.

2. Unauthorized workers to the construction site discharge water in concrete, concrete water consumption.

Prevention: 1. Admixtures content should be appropriate, measures to be accurate.

2. To remind the site annual mean temperature is low, pay attention to heat conservation, and polycarboxylate admixtures on the water-sensitive, non-free water.

Prepared with naphthalene superplasticizer concrete pouring the same site, resulting in serious stick wall form removal mode phenomenon when a superplasticizer mix station during the test application, and naphthalene superplasticizer with different mix two sites were to provide concrete, due to a power failure site, a vehicle scheduling to polycarboxylate admixture preparation of concrete transferred to this site, the results of the site was found in the wall of a serious stick form removal mode.

Cause: The two are different in nature from the preparation of concrete admixtures for different setting time, shrinkage of different sizes cause.

Prevention: 1. Admixtures of two different nature of concrete can not be simultaneously prepared for the same position.

2. Identified the problem, to communicate in advance with the site, the appropriate form removal time delay.

Preparation of naphthalene superplasticizer remaining material mixed concrete, resulting in poor performance of concrete production staff of a small amount of the remaining naphthalene superplasticizer prepared with concrete mixed with superplasticizer prepared concrete results 190 mm slump concrete factory, sent to the site have only 100 mm, and almost no mobility, when the vibrator vibrated a long time after the pull to close the hole.

Cause: The two types of different additives mixed adverse events.

Prevention: Two admixtures must be strictly separated from the use, production will stop when the best, will be cars, will be the site.

Preparation of two water-reducing agent mixed in a concrete strength of low additive mixing station workers unloaded when the small amount of naphthalene superplasticizer error unloading into the polycarboxylate admixture, the admixture prepared with a mixture of concrete, of additive not only large, but poor mobility workability, slump loss of speed, but the setting time delay, compared with the same strength of concrete specimens of concrete with low cement content 30% ~ 50%. Reason: provided by two different admixture preparation for the setting time of concrete are different sizes cause shrinkage.

Prevention: the current technical conditions, the two additives can not be mixed, and the production process, to strengthen management, clearly marked, to prevent such accidents.

Comments polycarboxylate superplasticizer introduced into China in time is not long, it's the mechanism we Huan did not fully grasp its the 认识 过程 need a job and the concrete of knowledge is not derived from Lilunershi Laizishiyan, Dan The test was carried out under the guidance of the basic theory of. Now on the market the type of superplasticizer more and more, but they are not necessarily the same synthetic route, the source of raw materials, the quality is different, there are differences in production processes, product performance so there will be greater difference. Our understanding of superplasticizer also need to constantly experiment to get the sum, based on the above lessons that superplasticizer if used improperly, can cause the same rapid coagulation, retardation, bleeding , stratification, intensity decreases and so on
Sodium Naphthalene Formaldehyde
Melamine Based Plasticizer
Polycarboxylate superplasticizer