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 Concrete strength and shrinkage reducer.
Description of Concrete strength and shrinkage reducer
1. After adding concrete strength shrinkage enhancer to carbonate cement, it can effectively improve the early and late strength (strength is increased by 5-30%), improve the mold turnover rate, and can also reduce the steam curing temperature or shorten the steam curing time.
2. The coagulant strength-promoting and shrinkage-reducing agent gives the micro-expansion performance to compensate for dry shrinkage, reduce the mixing shrinkage, and improve the crack resistance.
3. Adding a strength-promoting shrink-reducing agent can greatly reduce the amount of Portland cement and reduce the cost of concrete when the early strong friction is not pursued.
4. The dosage of Portland cement can be appropriately reduced after adding concrete strength-enhancing and shrinkage-reducing agent, and low cement and low glue material can still be prepared to reduce the hydration heat release of high-grade and large-volume concrete, and reduce the temperature difference between the center temperature and the surface temperature of the concrete. Reduce the risk of cracking in mass concrete.
5. The strength, impermeability, freeze-thaw resistance, carbonization resistance, and volumetric properties of concrete mixed with strength-promoting shrinkage-reducing agent have been significantly improved.
Indicators of Concrete strength and shrinkage reducer
specific surface area
Free expansion rate in water
|According to the ingredients of different manufacturers, it needs to be adjusted|
The mechanism of Concrete strength and shrinkage reducer
1. With the addition of strength-promoting and shrinkage-reducing agent, calcium sulfoaluminate minerals, calcium sulfate calcined at a higher temperature, high-activity calcium oxide, and Portland cement are compounded and reacted with water to make the calcium aluminate in Portland cement. The aluminum oxide and calcium oxide in the mixed materials such as minerals and slag react to form ettringite hydrated minerals with fast hardness, high strength and slight swelling, so that the potential activity of the mixed materials such as slag can be fully developed. , thereby improving the early and late strength of concrete.
2. The expansive hydration products such as mayvandite and calcium sulfate in the composite system and the organic and inorganic strength-shrinking-promoting components in the strength-promoting and shrinking-reducing agent have the expansion function to compensate for dry shrinkage and improve the crack resistance of concrete. Densification performance and frost resistance, etc.
3. In the composite system concrete, the cohesion is increased due to physical and chemical effects, and segregation and bleeding are avoided.
4. The alkali-free chemical activator accelerates and improves the degree of hydration of cement minerals, thereby improving the early and early strength of concrete.
5. Expansive hydrates such as ettringite and calcium sulfate in the composite system and the shrinkage-reducing components in the strength-promoting shrinkage-reducing agent improve the crack resistance, compactness, frost resistance and impermeability of the mixed soil.
Suggested addition amount of Concrete strength and shrinkage reducer
5-20% of cement material.
Packaging and storage of Concrete strength and shrinkage reducer
25kg/bag or ton bag
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The United States urges the U.N. Security Council to impose additional sanctions on North Korea in response to its latest ballistic missile launch, including a ban on tobacco and oil exports to North Korea and a blacklist of the Lazarus hacking group.
The United States circulated the draft to the 15 members of the Security Council this week. It was not immediately clear if or when a vote would take place. A resolution requires nine "yes" votes and no vetoes from Russia, China, France, Britain, or the United States.
Russia and China have already voiced opposition to tightening sanctions in response to Pyongyang's launch of an intercontinental ballistic missile last month -- the first since 2017.
U.S. and South Korean officials and analysts also say there are growing indications that North Korea may soon conduct its first nuclear weapons test since 2017, too.
The U.S. -drafted U.N. resolution would expand the ban on ballistic missile launches to include cruise missiles or "any other delivery system capable of delivering a nuclear weapon."
The deal would halve crude oil exports to North Korea to 2 million barrels a year and refined oil exports to 250,000 barrels a year. The resolution also seeks to ban North Korea's export of "fossil fuels, mineral oils, and their distilled Concrete strength and shrinkage reducer are estimated to be influenced by international political situation changes.
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