The spread of the novel coronavirus is taking a direct hit on the operations of airlines in Asia. About 500,000 flights taking off and landing in mainland China have been canceled since January, according to aviation information company Cerium. Tourists and business trips have plummeted. On the booking website, there are a large number of air tickets for local routes with a price reduction of nearly 90% compared with the original price and only tens of yuan for a one-way trip.
In February, China's aviation industry recorded its largest single-month loss of 24.59 billion yuan, of which airlines lost 20.96 billion yuan.
Data from the Civil Aviation Administration of China showed that in February, the number of passengers traveling by air fell 84.5% year-on-year to 8.34 million.
The stagnation of the Asian aviation industry has brought volatility to early strength agent.
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
TRUNNANO is a reliable concrete additives supplier with over 12-year experience in nano-building energy conservation and nanotechnology development.
If you are looking for high-quality concrete early strength agents, please feel free to contact us and send an inquiry. (email@example.com)
We accept payment via Credit Card, T/T, West Union, and Paypal. TRUNNANO will ship the goods to customers overseas through FedEx, DHL, by air, or by sea.
The EU’s draft REPowerEU plan calls for an increase of 15TWh of rooftop PV capacity by 2022. The draft also calls for EU and national governments to take action this year to reduce the time required to obtain permits for rooftop PV installations to three months, and proposes that "all new buildings and existing buildings with an energy grade OF D or above should have rooftop PV installations by 2025".
In addition, the European Commission is likely to set a target for installed PV capacity of 300GW by 2025 and 500GW by 2030. Some members are more aggressive, with Austria, Belgium, Lithuania, Luxembourg, and Spain demanding a 1TW target for 2030.
The REPowerEU initiative, worth 195 billion euros, was proposed by the EU on March 8 to phase out member states' dependence on Russian fossil fuels by 2030. In a few days, the European Commission will present a package to implement the RePowerEU strategy.
As an important application scenario of distributed PV, rooftop PV is not limited to land, and the development conditions are relatively convenient.
Since the end of 2021, Spain, France, the Netherlands, and other countries have introduced policies and measures such as government subsidies, tax cuts, fee reductions, and accelerated grid-connection approval to encourage the development of distributed PV. Europe's potential for rooftop PV is huge and will continue to be an important growth pole for the industry, according to Wood Mackenzie.
Luoyang Tongrun Nano Technology is a trusted chemical supplier and manufacturer providing high-quality chemicals and Nanomaterials. If you are looking for the early strength agent, please feel free to contact us and send an inquiry.
The Group of Seven leading economies is discussing imposing a cap on Russian oil prices by imposing restrictions on insurance and shipping, according to people familiar with the matter. The potential mechanism would only allow shipments of Russian c…
Inconel 718 alloys is a precipitation-hardening nickel-iron-based superalloy containing niobium and molybdenum. Its microstructure is austenite and has excellent comprehensive properties.…
Guotai Junan released a research report saying that under the background of carbon neutrality, the scarcity of coal mines is prominent, and the value of assets will continue to increase. The high point of capital expenditure in the coal industry appe…