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Cementing Retarder (Part 2)

4、 Retarder theory

Four theories: adsorption theory, complex formation theory, precipitation theory and (Ca (OH) 2 crystallization theory.

(1) According to the adsorption theory, most organic retarders have surface isoactivity and can be adsorbed at the solid-liquid interface of cement particles, which changes the hydrophilicity of the surface of cement particles and forms a retarder film that can inhibit cement hydration, resulting in the extension of concrete setting time.

(2) The retarder molecule can interact with the Ca2 + ion concentration produced by cement hydration to prevent the formation of cement hydration phase and produce the function of retarder. Sodium tripolyphosphate forms a stable complex with Ca2+, and the crystal growth of aquatic products delays the hydration of C3S and C3a.

(3) According to the precipitation theory, organic or inorganic retarders prevent the contact between cement particles and water by forming an insoluble thin layer on the surface of cement particles, thus delaying the hydration of cement and retarding the setting.

(4) According to the nucleation inhibition theory of precipitated (Ca (OH) 2 product, the retarder has the retarding effect by adsorbing on the (Ca (OH) 2 product core and inhibiting the continuous production of (Ca (OH) 2 crystallization.

5、 Retarder

Retarder (HN) series products are a new type of concrete admixture independently developed and produced by Qingdao Zoranoc Oilfield Chemical Co., Ltd. This product improves the work ability of fresh concrete and has excellent slump retention ability. The concentration of Ca2 + on the surface of cement can be retarded by the formation of a "hydrogen rich layer" of Ca2 + on the surface of cement, which can also inhibit the formation of a "hydrogen rich layer" of Ca2 + on the surface of cement, which can inhibit the formation of a "hydrogen rich layer" of Ca2 + on the surface of cement. With the progress of hydration process, this unstable complex will decompose itself, and the hydration will continue to proceed normally without affecting the later hydration of cement. The addition of this product can improve the dispersion of fluid loss additive, prolong the setting time of concrete and do not affect the development of concrete strength. This product is non-toxic, non flammable and has no corrosion effect on reinforcement. It can be widely used in all kinds of pumped concrete construction such as buildings, roads, bridges, hydraulic engineering and underground engineering.

Technical performance:

1. This product is suitable for large slump concrete and has excellent slump retention ability.

2. This product can also reduce the peak value of cement hydration heat release and reduce the generation of concrete temperature cracks.

3. Good plasticity can significantly prolong the transportation time of commercial concrete and the residence time on the construction site, and reduce the time loss.

4. In the compounding of pumping agent, this series of products can completely replace the original retarding components in the formula according to the experimental effect, and is better than the performance effect of the benchmark pumping agent.

5. This series of products are used in naphthalene series, aliphatic, amino, polycarboxylic acid and other admixture masterbatch.

6. According to the limitations of ground materials in different regions, the performance of products is different. Homogeneity index: according to the performance index of the product and the requirements of users, it meets the national, industrial or enterprise standards.


1. In the compound of ordinary pumping agent, HN (5-15) kg is directly added to each ton of liquid pumping agent, which is 0.01% - 0.1% of the dosage of cementitious material, which can completely replace the dosage of sodium gluconate;

2. Like the dosage and use method of sodium gluconate, the dosage can be adjusted reasonably according to seasonal requirements;

3. Adjust the dosage reasonably according to the requirements of each place and different seasons, and observe the setting time.

matters needing attention:

1. When the type of cement is changed or new cement is introduced, the compatibility test with cement shall be carried out.

2. For those requiring retarding concrete, the setting time shall be checked in advance according to the trial mix of concrete.

3. The mixing amount must be correct according to the test mix proportion, and the concrete shall be poured in strict accordance with the construction specifications.

4. When it is used with other admixtures, its compatibility shall be checked first.

5. During winter construction, in order to improve the early strength of concrete, the cement dosage of concrete should be adjusted appropriately.

6. As with conventional concrete works, the maintenance must be strengthened according to the construction specifications.

Packaging and storage:

1. The product shall be stored away from moisture and sunshine.

2. The unopened shelf life of this product is two years. If there is precipitation during the warranty period, it will not affect the effect after mixing.