A: concrete admixture is meant to improve and adjust the performance of concrete and mixing material.
Two: concrete admixture ( English: concrete admixtures ) referred to as the additive, is refers in the concrete mixing with the incorporation process is used to improve the performance of concrete material. Concrete admixture is generally not greater than5% cement quality.
Three: water-reducing agent can improve the strength of concrete, it is defined as : to ensure the concrete workability conditions, having water reducing and reinforcing effects of admixture.
Four: water-reducing agent function: the cement particle dispersion, improve the workability, reduce water use, thereby improving the cement base material density and hardness, increase the liquidity.
Five: the water reducing rate is equal to or greater than 14% is called a superplasticizer, greater than or equal to25% of the water reducing agent called high performance water-reducing agent ( such as poly carboxylic acid ).
Six: concrete admixture product quality must be consistent with national standards" concrete" ( GB8076-2008) regulations. According to the main function is divided into four categories:
(1) to improve the performance of concrete mixture and admixture, including water reducer, air entraining agent and pumping aid;
(2) adjusting the setting time of concrete, hardening properties of additives, including retarder, early strength agent and accelerator;
(3) to improve the durability of concrete admixture, including air entraining agent, waterproofing agent and antirust agent;
(4) to improve the performance of concrete admixture, including filling agent, expansive agent, antifreeze agent, coloring agent, waterproofing agent and pumping aid.
Seven: action of water reducer principle: water-reducing agent is usually a surfactant, an anionic surface active agent. It is adsorbed on the particle surface of cement particles display electrical properties between particles with the same charge, due to mutual exclusion, so that the cement particles are dispersed and release particles in excess water and produced water reducing effect. On the other hand, because of the addition of water reducer, cement particle surface formation of adsorption film, poly carboxylic acid water reducing agent action mechanism mainly is the side chain" comb" or" dendritic" structure on the main chain, also can make the cement particles charged sulfonate or other groups, can play the traditional action of water reducer, more important is adsorbed on the surface of cement particles once the main chain, chain and other particles on the surface of branched form vertical crossing, hindered the particles close to each other, thereby dispersing ( i.e. water reducing effect ). The steric effect for a long time, therefore, the dispersion of poly carboxylic acid water reducing agent is more durable.
Eight: water-reducing agent types of lignin sulfonate, naphthalene superplasticizer, melamine superplasticizer, polycarboxylate superplasticizer, amino sulfonate water reducer. Here are some of the larger amount of water reducing agent on the market
8.1: lignin sulfonate: it belongs to ordinary water-reducing agent, it is the raw material lignin, generally from softwood lignin extracted, by alcohol, coniferyl alcohol, to extend the three ethyl alcohol lignin monomer polymerizing, used for mortar could be improved in construction, liquidity, improve strength, the water reducing rate in5%10%.
8.2: naphthalene sulfonate water reducing agent: China is the earliest use of high efficiency water reducing agent, is naphthalene by sulfonation in sulfuric acid, and formaldehyde condensation product, which belongs to the anionic surface active agent. The water reducing agent with different appearance depending on the product is light yellow to dark brown powder, easy to dissolve in water, cement and many other powder material dispersion is good, the water reducing rate of 25%.
8.3: melamine superplasticizer: is the melamine by sulfonation in sulfuric acid, and formaldehyde condensation product, so the chemical name is sulfonated melamine formaldehyde resin, which belongs to the anionic surface active agent. The water reducing agent for the appearance of white powder, easy to dissolve in water, good dispersion of powder materials, high water reducing rate, its mobility and self repairing well.
8.4: poly carboxylic acid water reducing agent: it is only in recent years developed a new type of high performance water-reducing agent, it has high water reducing rate, fluidity, permeability. Enhance the strength of cement concrete.
Nine: admixture name and definition
9.1water reducing agent
Water-reducing admixture ordinary water-reducing agent in concrete slump is basic and same condition, can reduce the mixed with water additive. Commonly used water-reducing agent is anion surface active agent.
High efficiency water reducing agent superplasticizer in the slump of the concrete base under the same conditions, can greatly reduce water mixed with admixture.
Retarding and water-reducing agent set retarding and water-reducing admixture set retarding and water reducing admixture.
Early strength water-reducing agent hardening accelerating and water reducing admixture both the early strength and water reducing admixture.
Air-entraining water-reducing agent air entraining and water reducing admixture air entraining and water reducing admixture.
9.2: the early strength agent of hardening accelerator to improve the early strength of concrete, and has no significant influence on later strength additive.
9.3: retarder set retarder prolong the setting time of concrete admixture.
9.4: air entraining admixture air-entraining agent in concrete mixing process can introduce a lot of uniform distribution, stable and closed tiny bubble admixture.
9.5 waterproof agent water repellent admixture can reduce the concrete under the hydrostatic pressure permeability admixture.
9.6: rust inhibitor anti-corrosion admixture can inhibit or reduce the reinforced bar in the concrete or other embedded metal corrosion admixture.
9.7: gas forming admixture concrete air-entraining agent preparation process due to a chemical reaction, gas, and make the concrete to form large stoma admixture.
9.8: expanding admixture expansive agent can make the concrete to produce certain volume expansion admixture.
9.9: antifreeze anti-freezing admixture can make concrete at negative temperature hardening, and within the stipulated time to achieve enough antifreeze, strength additives.
9.10: coloring admixture colorant preparation has stable color admixture of concrete.
9.11: flash setting admixture accelerator can make rapid setting and hardening of concrete admixture.
9.12: pumping agent pumping aid can improve concrete pumping performance additive. Production of pumping agent materials superplasticizer, retarder, air entraining agent and thickening agent.