Concrete anti-segregation agent increases concrete viscosity and water retention, increases concrete slump-preserving coating agent Hubei segregation agent manufacturer

The abnormal setting time of concrete generally manifests itself in three types: excessive retarded setting, rapid setting and false setting. There are many factors that influence the abnormal condensation of cement concrete. Concrete admixtures, cement, admixtures, ambient temperature and wind speed may ultimately lead to the occurrence of abnormal condensation of cement concrete. Judging from the quality of concrete projects at this stage, the type of retarder, improper retarder dosage, incompatibility between admixtures and cement, and ambient temperature are the main reasons for abnormal condensation of cement concrete and even accidents in concrete projects.

Concrete anti-segregation agents increase concrete viscosity, water retention and increase concrete slump retention

Causes of excessive retardation of concrete

(1) Retarder in concrete admixtures Excessive amounts of components, especially when the sucrose content is high;

(2) Overmixing of concrete admixtures caused by man-made or mechanical failures;

(3) Turning into fly ash or Ore powder is mistakenly used as cement;

(4) The concrete mix ratio is improperly designed and there are too many admixtures, especially when the temperature of the concrete pouring environment is low;

(5) Temperature Influence, the temperature is too low;

(6) Maintenance is not in place, especially when the temperature is too low;

(7) The air content of the concrete is too large, causing the air content of the concrete to reach 8-10 %;

(8) The concrete slumps are too large or even segregate and bleed, resulting in high fly ash content and high water-cement ratio on the surface of the concrete;

Causes of rapid concrete setting

(1) No retarder is added to the concrete admixture or the amount of retarder is not enough;

(2) Cement using anhydrite and fluorine-containing gypsum as the setting regulator should be When using lignin sulfonate water-reducing agents, rapid setting of concrete is likely to occur;

(3) The water-cement ratio is low, the maintenance is not in place, and the ambient temperature is too high, the wind will cause premature failure of the concrete. Water cement hardening accelerates;

(4) Sulphoaluminate cement or high alumina cement is used;

(5) C3A content in cement is high and alkali content is high;

Causes of false setting of concrete

(1) The ambient temperature is too high, the wind is too strong, the concrete loses water prematurely, and the maintenance is not in place and it is not covered in time, especially for high-grade concrete prepared with carboxylic acid admixtures. At this time, the surface of the concrete quickly loses water and becomes hard, while the concrete in the lower layer is still relatively soft and has not condensed;

(2) The adsorption of concrete admixtures by cement, admixtures, sand and gravel aggregates, etc. If the conditions of time, pump pressure, and ambient temperature suddenly increase, the slump will be lost quickly, and the concrete will become loose and like tofu. The main reason is that the admixtures and their types are related to changes in the adsorption capacity of cement;

(3) The temperature of the cement is too high, and the dihydrate gypsum in the cement dehydrates and turns into hemihydrate gypsum or anhydrous gypsum;

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Solution:

(1) In summer, it is best not to use cement with a temperature exceeding 80°C to mix concrete in a concrete mixing station;

(2) In summer, use underground Cold water (add ice if necessary);

(3) Maintain concrete in time to prevent premature loss of water or freezing;

(4) Before construction, make cement and Adaptability test of concrete admixtures, mixing concrete to observe fluidity loss, and examining the setting time of concrete at the prevailing temperature. Determine the suitability of concrete admixtures;

(5) Maintenance of mixing station instruments and equipment for reliable operation;

(6) Concrete admixture products must be inspected, reliable, and of stable quality;

(7) Appropriate concrete mix ratio;

(8) When encountering abnormally solidified concrete, analyze the specific problems in detail and remove them as soon as possible if they endanger the quality of the project. The sooner the better. Generally speaking, if excessive retardation exceeds 4 days, the loss of concrete strength will be serious; when false concrete setting occurs, cement mortar of the same strength grade can be used to remix the concrete before pouring or use the mortar to plaster the concrete surface. Collect light. After the concrete is quickly set, if it is not poured into the formwork, it will be discarded. If it is poured into the formwork, it will be cut out or retained depending on the specific situation.