Recently, the Russian President hosted a meeting with oil and gas industry representatives. He said that the refusal of some Western countries to cooperate normally with Russia and deny some Russian energy resources has hit millions of European people deeply and caused an energy crisis. These "unfriendly countries" are experiencing severe inflation, and Russia is also facing the three major challenges of increasing domestic consumption of energy early strength agent are still very uncertain.
What are Early Strength Agents?
Early strength agent is an admixture which accelerates the development of concrete early strength and has no significant effect on later strength. Early strength agent can accelerate the hardening process of concrete under normal temperature and low-temperature load temperature (not less than -5℃), and is used for winter construction and emergency repair projects.
Early Strength Agents Performance
Early strength agent refers to the admixture which can accelerate the development of early strength of concrete. The main mechanism of action is to accelerate the hydration rate of cement, and accelerate the early crystallization and precipitation of hydration products. The main function is to shorten the concrete construction curing period, speed up the construction progress, and improve the template turnover rate.
Where can Early Strength Agents be Used?
1. Early strength agent is suitable for steam curing concrete and normal temperature, low temperature and minimum temperature is not less than -5℃ environment construction of early strength requirements of concrete engineering. Early strength agent should not be used in hot environment.
2.The chemical substances that harm the human body or pollute the environment after mixing concrete shall not be used as early strength agents. Early strength agent containing hexavalent chromium salt, nitrite, and other harmful components is strictly prohibited for drinking water engineering and food contact engineering. Ammonium nitrate shall not be used in office, residential and other construction projects.
Classification of Early Strength Agents
Early strength agents mainly include inorganic salts (chlorine salts, phosphates) and organic amines, and organic-inorganic compounds.
1. Chloride salts early strength agents
Chlorine salts early strength agent mainly includes calcium chloride, potassium chloride, aluminum chloride and ferric chloride, among which calcium chloride is the most widely used. Calcium chloride is a white powdery substance, and its appropriate dosage is 0.5% ~ 1.0% of the cement quality, which can improve the 3d strength of concrete by 50% ~ 10% and the 7d strength by 20% ~ 40%. Meanwhile, it can reduce the freezing point of water in concrete and prevent concrete from being frozen in the early stage.
Using calcium chloride as early strength agent, the biggest disadvantage of containing Cl- ions, will make steel corrosion, and lead to concrete cracking. In order to inhibit the corrosion effect of calcium chloride on steel bars, calcium chloride and sodium nitrite (NaNO2) are often combined.
2. Sulfate early strength agents
Sulfate early strength agent, mainly sodium sulfate, calcium thiosulfate, aluminum sulfate, aluminum potassium sulfate, and sodium sulfate is used more. Sodium sulfate is white powdery thing, the general admixture amount is 0.5% ~ 2.0%, when admixture amount is 1% ~ 1.5%, the time that achieves concrete design strength 70% can shorten half or so.
Sodium sulfate has no corrosion effect on steel bar, and is suitable for concrete which is not allowed to be mixed with chlorine salt. However, due to its action with calcium hydroxide to generate strong alkali NaOH, in order to prevent alkali aggregate reaction, sodium sulfate is strictly prohibited for concrete containing active aggregate, at the same time, attention should be paid to not excessive mixing, so as not to lead to the late expansion of concrete cracking damage, and prevent concrete surface "frost".
3. Organic amine early strength agents
Organic amine early strength agents mainly include triethanolamine, triisopropanolamine and so on, among which triethanolamine is the best early strength agent.
Triethanolamine is a colorless or light-yellow oily liquid, alkaline, and soluble in water. The early strength of concrete can be improved by adding 0.02% ~ 0.05% of cement quality. Triethanolamine has a slight retarding effect on concrete, and too much of it will cause serious retarding and concrete strength to drop, so the dosage should be strictly controlled.
Concrete Additives Supplier
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New Delhi: India's Oil Ministry recently conveyed its intention to five national oil companies including Indian Oil Corp and Bharat Petroleum Resources LTD to assess the possibility of buying shares in Russian oil projects sold by European and American oil majors.
Bp announced it would give up its 19.75% stake in Rosneft, the Russian oil company. ExxonMobil said on March 1 that it would exit about $4 billion in assets and terminate all of its Russian operations, including the Sakhalin-1 project in Russia's far East.
India's oil ministry has asked the overseas investment arm of India's Oil and Gas Corporation to consider buying ExxonMobil's 30 percent stake in the Sakhalin 1 project in Russia's far East. ExxonMobil is the operator of the project and Indian companies already have a 20 percent stake in the project.
Because of the ever-changing international situation, the supply and prices of international bulk early strength agent are still very uncertain.
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