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What are the types of concrete admixture and what are their respective functions?

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2022-09-09

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What are the types of concrete admixtures and what are their respective functions??

Concrete admixture refers to the material added to improve and adjust the performance of concrete. At first, the concrete admixture is only to save cement, and with the increasing types of concrete admixtures, it is more used to improve the performance of concrete, so that the construction progress is accelerated, and the construction process is more convenient. Different types of admixture also have different effects. So, what is the concrete admixture?

What is Concrete Admixtures? Concrete admixtures are divided into four categories according to their main functions:

(1) Admixtures to improve the variable performance of concrete mixing flow, including various water reducing agents, air entraining agents and pumping agents;

(2) Admixtures for adjusting the setting time and hardening performance of concrete include retarder, early strength agent and accelerator;

(3) to improve the durability of concrete additives, including air entrainment agent, waterproof agent and anti rust agent;

(4) Improve other properties of concrete admixtures, including oxygenators, expansive agents, antifreeze agents, colorants, waterproofing agents and pumping agents.

ordinary water reducing agent: When the concrete slump is basically the same, the mixing water consumption can be reduced.

early strength agent: Accelerate the early strength development of concrete.

retarder: Extend the setting time of concrete.

Air-entraining agent: A large number of evenly distributed, stable and closed microbubbles are introduced in the concrete mixing process.

Superplasticizer: When the concrete slump is basically the same, the mixing water consumption can be greatly reduced.

early strength water reducing agent: It has both early strength and water reduction function.

Slow and return agent: It has the function of slow and also water agent.

entrained air water reducing agentEntrained air and water reducing function.

inhibitors: Decrease the water permeability of concrete under hydrostatic pressure.

rust inhibitor: Inhibits or reduces corrosion of other metals in steel or concrete.

gas agent: During the preparation of concrete, due to chemical reactions, gas is released and a large number of pores are formed in the concrete.

expansion agent: Make the concrete produce a certain volume expansion.

Antifreeze: Make the concrete harden at negative temperature and achieve sufficient antifreeze and strength within the specified time.

Colorant: Preparation of color-stable concrete.

Accelerator: Make concrete set and harden quickly.

Pumping agent: Used to improve the pumping performance of concrete mixtures.

Within the prescribed dose, the admixture generally has no side effects.

In order to speed up the solidification speed of concrete and the anti-freezing of winter construction in building construction, high alkali concrete expansive agent and concrete anti-freezing admixture containing urea and ammonia are added into concrete. This kind of admixture contains a large amount of ammonia materials, which decreases with the change of environmental factors such as temperature in the wall, and the concentration of ammonia in indoor air is greatly increased due to the slow release of ammonia from the wall. Especially in summer, when the temperature is high, the ammonia is released from the wall faster, causing the ammonia concentration in the indoor air to exceed the standard.

Ammonia has high solubility, so it is often adsorbed on the skin and conjunctiva, causing irritation and inflammationAmmonia can paralyze the respiratory cilia, damage the epithelial tissue, make the pathogenic microorganisms easy to invade, weaken the body's resistance to disease. After ammonia is inhaled into the lungs, it is easy to enter the blood through the alveoli, and combine with hemoglobin to destroy the oxygen transport function. After inhaling a large amount of ammonia in a short period of time, symptoms such as tears, sore throat, hoarseness, cough, chest tightness, and difficulty breathing will appear. In severe cases, pulmonary edema and adult respiratory distress syndrome may occur, as well as respiratory irritation.

Of course, while the concrete admixture brings convenience to people's construction, the use of some concrete admixture will also cause pollution to the indoor environment. Adding high-alkali concrete expansive agent to concrete and concrete antifreeze containing urea and ammonia as admixture will greatly increase the concentration of ammonia in indoor air, thus becoming the main pollution source of decoration. This is also the owner in the use of concrete admixture needs special attention.

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