The difference between the use of retarder and other admixtures

(1) Characteristics

Retarder and retarding superplasticizer have different retarding effects on the slurry and concrete surface. The retardation effect increases with the increase in dosage. Over-admixture will cause the complete cessation of concrete hydration. As the temperature rises, the retarding effect of hydroxycarboxylic acids and salts decreases sharply. When the weather decreases, the retarding time increases and the initial strength decreases more significantly. Hydroxycarboxylate retarder will increase the bleeding of concrete, especially in lean concrete with high water-cement ratio and low water-cement dosage, resulting in segregation.

Various retarders and retarding water-reducing agents are mainly used to slow down and inhibit the hydration of C3A minerals and C3S mineral components. The impact on C3S is much smaller, so they do not affect the final stage of cement mortar. Hydration and long-term strength improvement.

The key index of the initial setting time of the retarder is that the initial setting is delayed by about 90 minutes compared with the standard concrete, that is, the initial setting time difference exceeds +90 minutes. However, the final setting time difference is not uniformly required. Due to the ultra-retarding The index of coagulant and general retardant is quite different. A good retardant can reduce concrete rebound within a reasonable dosage. Therefore, general water-reducing agents have retarding properties and must have air-entraining properties, so they are not suitable for over-mixing.

(2) Purpose and application limitations

Retarder, retarding water-reducing admixture and retarding high-efficiency water-reducing admixture can be used in large-volume concrete, rolled concrete, hot air Concrete for decoration projects under Hou standards, large-scale poured concrete, concrete to prevent cold joints, concrete that requires parking for a period of time or long-distance transportation, floor paint vibration-free concrete, slip form construction or pull-out concrete Concrete for mold decoration projects and concrete whose initial setting time needs to be slowed down. Retarding high-efficiency water-reducing admixture can be used to produce recycled concrete.

Retarder, retarding water-reducing agent and retarding water-reducing agent are suitable for use in concrete with a daily minimum temperature of about 5℃ for decoration projects. They are not suitable for independent use in concrete with early strength requirements and Steam-cured concrete. Retarders such as citric acid and potassium sodium tartrate are not suitable for independent use in lean concrete with low concrete dosage and large water-cement ratio.

Note: Quote from “550 Questions on Concrete Admixtures”

At present, there is a retarder that has a very obvious effect on slowing down the initial setting time.

The retarder (HN) product series is a new type of concrete admixture independently developed and manufactured by Tianjin Dingchang New Materials Co., Ltd. This product improves the workability of freshly mixed soil and has high-quality Slump maintenance potential. This product can convert the alkaline substances in concrete hydration substances and the Ca2+ of mineral acid into unstable complexes, reduce the solubility of Ca2+ in the liquid phase in the early stage of hydration, and delay the crystallization of CH. It also adsorbs on the surface of concrete hydration particles, forms hydrogen bonds with the oxygen ions in the “silicon-rich layer”, and forms the original film on the surface of concrete particles to inhibit the development of its hydration reaction, thus forming a retarding effect. As the hydration process progresses, this unstable complex will refine itself, and the hydration will continue to proceed smoothly, without necessarily affecting the final hydration of the concrete. The addition of this product can improve the dispersion of the water-reducing agent, extend the initial setting time of the concrete, and will not affect the rebound transformation of the concrete. This product is harmless, non-flammable, has no rusting effect on steel bars, and can be used in concrete for various underwater concrete decoration projects such as housing construction, roads, bridges, hydraulic engineering and underground construction.

1. Process characteristics:

1. This product is suitable for large slump concrete and has high slump maintenance potential.

2. This product can also reduce the hydration heat absorption valley value of concrete and reduce the formation of temperature gaps in concrete.

3. Excellent ductility can significantly increase the transportation time of concrete and the stay time at the construction site, and reduce time-lapse damage.

4. In the compounding of underwater concrete agents, this product series can completely replace the retarding components of the secret recipe based on experimental results, and has better performance than standard underwater concrete agents.

5. This product series is used in naphthalene series, aliphatic, amino, polycarboxylic acid and other types of water reducing agent masterbatch.

6. According to the restrictions on building materials in different regions, the characteristics of the products are diversified.

2. Homogeneity index

Based on the product’s performance parameters and customer requirements, it complies with Chinese, manufacturing or product standards.

3. Instructions for use:

1. In general underwater concrete agent compounding, HN (5-50) KG is immediately added to one ton of liquid underwater concrete agent. It is 0.01%-0.1% of the dosage of the admixture, which can completely replace the dosage of sodium gluconate;

2. The dosage and instructions for use are the same as those of sodium gluconate, and the dosage can be effectively adjusted according to periodic regulations ;

3. Adjust the dosage and observe the initial setting time according to the requirements of each region and different seasons.

IV. Frequently Asked Questions

1. When the type of concrete is changed or new concrete is introduced, a compatibility mode test with the concrete should be carried out.

2. If retarded concrete is required, the initial setting time should be tested in advance according to the concrete trial mix.

3. Be sure to add the appropriate amount according to the experimental mix ratio, and strictly follow the construction process when pouring concrete.

4. When using it with other water-reducing agents, first check its compatibility mode.

5. During the winter construction period, in order to increase the initial strength of the concrete, the concrete dosage of the concrete should be appropriately adjusted.

6. Basic concrete work�Similarly, maintenance must be carried out according to the construction process.

5. Packaging and Storage

1. Store this product to prevent moisture, cold, and sun exposure.

2. This product has a shelf life of two years. If it does not settle during the warranty period, it will not have any effect after being stirred and used.

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