Basic knowledge of common concrete admixtures
TIME:2019-06-13   READER:634

Concrete admixtures are divided into: admixtures for improving the properties of concrete mixes; admixtures for adjusting concrete setting time and hardening properties; admixtures for improving the durability of concrete; and admixtures for improving other properties of concrete.

1. Admixtures for improving the variable properties of concrete mixing streams

There are mainly concrete water reducing agents, pumping agents, air entraining agents and water retaining agents.

Water reducing agent: It is an admixture capable of reducing water consumption under the condition that the concrete slump is basically the same. Mainly divided into ordinary water reducing agent and high-speed water reducing agent. A water reducing rate less than or equal to 8% is called a common water reducing agent, and more than 8% is called a high speed water reducing agent.

Pumping agent: A concrete pumping agent that improves the pumping performance of concrete mixes.

Air entraining agent: It is an admixture that introduces air into the concrete mixture during the mixing process to form a large number of tiny, closed and stable bubbles.

Water retaining agent: A material used for construction performance and a material that can significantly delay drying time.

2. Admixture for adjusting concrete setting time and hardening performance

Mainly early strength agents, accelerators, retarders and so on.

Early strength agent: an additive that can increase the early strength of concrete and has no significant effect on late strength.

Accelerator: Used for concrete with quick setting requirements.

Retarder: An admixture that delays the setting time of concrete and has no significant effect on late strength.

Third, improve the durability of concrete admixture

Mainly air entraining agent, water repellent, rust inhibitor and mineral admixture.

Waterproofing agent: It can improve the anti-penetration performance of cement mortar and concrete.

Rust inhibitor: refers to an admixture that can inhibit or reduce the corrosion of steel and other metals in concrete.

4. Admixtures for improving other properties of concrete

It is mainly used as a shrinkage reducing agent, a swelling agent, an antifreeze agent, and an additive for adding concrete functions.

Reducer: Reduce the shrinkage of concrete or mortar.

Expansion agent: is an admixture that causes micro-expansion of concrete.

Antifreeze: Under appropriate negative temperature conditions, it can significantly reduce the freezing point of concrete, prevent concrete from being damaged, allow concrete to carry out hydration reaction, and obtain the expected strength in an appropriate time.

Adding concrete functional admixtures: Concrete is a structural material with good performance in many engineering fields such as civil engineering, and sometimes it needs other functions, such as static conductive agents and anti-wear agents.

Concrete admixtures are an integral part of concrete and are materials that improve the performance of fresh concrete and hardened concrete. Need to make it play a beneficial role, we need to further understand the different concrete admixtures, the correct choice and use.

It should be noted that the blending amount of the concrete admixture is not more than 5% of the mass of the cement.

Copyright: Shanxi Jiawei New Materials Co., Ltd. Record number: Jin ICP preparation *****