General requirements for specification and selecti

2022-07-22
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Concrete admixture refers to the material added to improve and adjust the performance of concrete. The application of concrete admixtures in engineering has been paid more and more attention. The addition of admixtures plays a certain role in improving the performance of concrete, but the selection, addition method and adaptability of admixtures will seriously affect its development. At first, concrete admixtures were only used to save cement, but with the increasing variety of concrete admixtures, they are more used to improve the performance of concrete, making the construction progress faster and the construction process more convenient

the specification for concrete admixtures includes many aspects, first, the selection and use of admixtures, second, the varieties of ordinary water reducing agents and high-efficiency water reducing agents and precautions during construction, third, the introduction of the varieties and construction of collective air entraining water reducing agents, and fourth, the introduction of the types and use of retarders and retarding water reducing agents, The fifth is about the varieties and use of early strength agents and early strength water reducing agents. The sixth is about antifreeze. In addition to these, there are some other admixtures that must be used when using concrete. Today we will focus on the first few aspects of the specification of concrete admixtures

What are the concrete admixtures

concrete admixtures are divided into four categories according to their main functions:

(1) admixtures that improve the rheological properties of concrete mixtures, including various water reducing agents, air entraining agents and pumping agents

(2) admixtures that adjust the setting time and hardening performance of concrete, including retarders, early strength agents and accelerators

(3) admixtures to improve the durability of concrete, including air entraining agent, waterproof agent and rust inhibitor

(4) admixtures to improve other properties of concrete, including aerating agent, expansion agent, antifreeze, colorant, waterproof agent and pumping agent

ordinary water reducing agent: it can reduce the mixing water volume under the condition that the slump of concrete is basically the same

early strength agent: accelerate the development of early strength of concrete

retarder: extend the setting time of concrete

air entraining agent: it can introduce a large number of uniformly distributed, stable and closed micro bubbles during concrete mixing

superplasticizer: under the condition that the slump of concrete is basically the same, it can greatly reduce the mixing water volume

early strength water reducing agent: it has both early strength and water reducing functions

retarding and water reducing agent: it has retarding and water reducing functions

air entraining water reducer: it has the functions of air entraining and water reducing

preventive agent: reduce the water permeability of concrete under hydrostatic pressure

rust inhibitor: inhibit or reduce the corrosion of reinforcement or other embedded metals in concrete

aerator: a large number of pores are formed in the concrete due to the chemical reaction and gas release during the preparation of concrete

expansion agent: make the concrete expand in a certain volume

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

colorant: prepare concrete with stable color

accelerator: make the concrete set and harden rapidly

pumping agent: it can improve the pumping performance of concrete mixture

within the specified dosage, the side effects of the admixture are basically very small

concrete admixture action

(1) it can reduce the water consumption of concrete Or the fluidity of concrete can be increased without increasing water consumption

(2) the setting time of concrete can be adjusted

(3) reduce bleeding and segregation Improve workability and water elutriation resistance

(4) can reduce the slump loss Increase the pumpability of pumped concrete

(5) can reduce contraction Adding expansion agent can also compensate for shrinkage

(6) delay the initial hydration heat of concrete Reduce the temperature rise speed of mass concrete and reduce the occurrence of cracks

(7) improve the early strength of concrete Prevent freezing under negative temperature

(8) improve strength, increase frost resistance, impermeability, abrasion resistance and corrosion resistance

(9) control alkali aggregate reaction Prevent reinforcement corrosion and reduce chloride ion diffusion

(10) make concrete with other special properties

(11) reduce the viscosity coefficient of concrete, etc

price of concrete admixture

water reducing agent is divided into powder and liquid. The price of liquid is about 2000~3000 a ton

the price of large cover with high solid content of air entraining agent paste is more than 10000 yuan a ton

note: this price is for reference only! Due to different regions, of course, the price will also vary. For more relevant price details, please refer to the local dealer

concrete admixture manufacturer

I Annual user recommendation excellent brand enterprise of Chinese concrete admixture

Liaoning Cologne Fine Chemical Co., Ltd.

Jiangsu Bote new materials Co., Ltd.

kezhijie New Materials Group Co., Ltd.

Hebei concrete admixture factory

Beijing New Century Oriental Building Materials Co., Ltd.

Ma'anshan Zhonghai new materials Co., Ltd.

Tianjin Feilong concrete admixture Co., Ltd.

concrete admixture Specification

the dosage of concrete admixtures should not be too much or too little, which should correspond to the amount of cementitious materials. When adding additives, it is necessary to refer to the dosage recommended by the production unit on the product package, and carefully read the precautions for use, the necessary conditions for the use of additives, etc. If the admixture contains some special chemical elements, such as chloride ion and sulfate radical, it needs to be added reasonably according to some regulations and cannot be used at will

editor's summary: some concrete admixtures are powdery, and the preservation of such admixtures is a very important problem. If they are not preserved properly, they are likely to damp the admixtures, so that they are caked, difficult to use, and waste materials. Therefore, the preservation of admixtures is also a problem that needs special attention. If the admixtures are liquid, they need to be placed in a dry and cool place, Because if it is affected by some external conditions such as sunlight and water, its performance is likely to be affected

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