What are the commonly used concrete admixtures?

With the continuous advancement of science and technology, concrete admixtures have become the fifth important component in addition to the four basic components of concrete. Concrete admixtures are characterized by many varieties and small dosages, which have a greater impact on the performance of concrete. They have the characteristics of low investment, quick results, can significantly improve the performance of concrete, and have significant technical and economic benefits. Therefore, admixtures have been increasingly used.

1. Concrete admixtures are divided into four categories according to their main functions

(1) Improvement Admixtures for improving the flow properties of concrete mixtures. Including water reducing agent, air entraining agent and pumping agent.

(2) Admixtures that adjust the setting time and hardening properties of concrete. Including retarder, early strength agent and accelerating agent.

(3) Admixtures that improve the durability of concrete. Including air-entraining agents, waterproofing agents and rust inhibitors.

(4) Admixtures that improve other properties of concrete. Includes air entraining agents, expanding agents, antifreeze, stains, waterproofing agents and pumping agents.

2. Current application status of concrete admixtures

Currently The admixtures commonly used in engineering mainly include water-reducing agents, air-entraining agents, early strength agents, retarders, antifreeze, etc. Concrete admixtures are mainly used in construction, roads, bridges, hydraulic engineering, underground, subways, tunnels, retarded concrete and commercial concrete, etc.

3. The development history of concrete admixtures

Nowadays, the application of concrete admixtures is becoming more and more common. After understanding the current application status of concrete, when was the concept of improving the performance of concrete first proposed? Let us understand the development history of concrete admixtures.

(1) In the early 1990s, the United States first proposed the concept of high-performance concrete (HPC), which was a successful combination of new superplasticizers and concrete material science. example.

(2) In 1824, British I. Aspdin obtained the patent for Portland cement, and cement concrete was widely used.

(3) In 1962, Japan’s Hattori Kenichi first used naphthalene sulfonate formaldehyde condensate (n≈10) as a concrete dispersant. In 1964, Japan’s kawangite alkali The company sells it as a product.

(4) In 1963, the Federal Republic of Germany developed a functional melamine sulfonate formaldehyde condensate, and at the same time, polycyclic aromatic hydrocarbons sulfonate formaldehyde condensation appeared.

(5) In 1966, Japan first applied high-strength concrete and began to produce prestressed concrete piles.

(6) From 1971 to 1973, Germany was the first to successfully develop superplasticizer into fluid concrete, and the vertical concrete pumping height reached 310m.

(7) The development direction is the research on HPC and the use of composite superplasticizer (CSP) to realize the full calculation method design of HPC mix ratio and CSP formula design.

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