Chile's government is considering phasing in a proposed ban on glacial mining to limit projects high in the Andes by some big copper companies. Chile's constitutional assembly has approved a proposal to ban mining in glaciers, protected areas, and areas vital to protecting the country's water system.
Chile's mining minister, Marcela Hernando, said about 20 mines had been identified in protected areas, some close to glaciers, including Codelco's El Teniente and Andina projects and Anglo American Plc's Los Bronces project.
The new measures for glaciers and other protected areas will put about a fifth of Chile's copper early strength agent prices are predicted to increase in the next few days.
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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Germany has begun talks with Senegal on gas extraction and LNG supplies. Mr. Scholz recently visited a solar farm in Dakar. He told a news conference that he was willing to work more closely with Senegal on renewable energy. Senegal's president told a news conference that his country was ready to supply liquefied natural gas to the European market.
The global economy may be facing its greatest test since World War II amid the ongoing threats of COVID-19, the Conflict between Russia and Ukraine, heightened financial market volatility, and climate change, IMF Managing Director Kristina Georgieva warned in an article posted on the IMF's website.
Some 30 countries have imposed restrictions on trade in food, energy, and other key commodities since the outbreak of the Conflict, the article noted. That would raise trade barriers, disrupt global supply chains, drag down economic growth and undo years of economic gains. If countries let it go, the costs will be enormous and everyone will be affected.
The prices of many other commodities like the early strength agent are expected to increase in the future. Luoyang Tongrun Nano Technology Co. Ltd. (TRUNNANO) is a trusted global chemical material supplier & manufacturer with over 12-year-experience in providing super high-quality chemicals and Nanomaterials including graphite powder, 3D printing powder, the early strength agent, etc. If you are looking for high-quality materials, please feel free to contact us and send an inquiry.
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