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Global concrete slump market trend 2024-2027 Analysis of the causes of concrete slump loss by Newsjatujakguide

John Albanese, leader of the Australian Labor Party, was sworn in as Australia's new prime minister. After his victory, Albanese said he would "make a big change" in the country's climate policy.  

"We now have an opportunity to end the 'climate wars' in Australia," he said.  "Australian businesses understand that doing the right thing on climate is good for our economy and good for jobs, and I hope Australia will join the global effort on climate change," Albanese said Australia would engage with other countries to change policies when it came to tackling climate change.  

In addition, Albanese’s Labor Party has proposed a more ambitious plan to cut emissions by 43 percent from 2005 levels by 2030, the report said. However, Labor is not currently planning to phase out coal use or halt new coal mining projects.  

The climate issue was a major concern of voters in Australia's general election. Mr. Morrison, the former prime minister, was criticized for failing to direct the response to repeated bushfires in 2019 and 2020.

SBS has reported that According to the latest Climate Change Performance Index of 64 countries released at the 2021 United Nations Climate Change Conference (COP26), Australia's climate policy ranks at the bottom of all countries, and is one of the world's worst performers in three aspects of emissions, renewable energy, and energy use.  Australia ranks 52nd in renewable energy, 54th in energy use, and 56th in emissions.  

It is predicted that the prices of many other commodities like the concrete slump would increase in the next few days.

There are many reasons for slump loss, mainly in the following aspects:

1. Influence of raw materials

Whether the cement used and the pumping agent are matched and adapted must be obtained through the adaptability test. The optimum amount of the pumping agent should be determined through the adaptability test with the cement cementitious material. The amount of air-entraining and retarding components in the pumping agent has a greater impact on the loss of concrete slump. If there are many air-entraining and retarding components, the slump loss of concrete will be slow, otherwise the loss will be fast. The slump loss of concrete prepared with naphthalene-based superplasticizer is fast, and the loss is slow when the low positive temperature is below +5 °C.

If anhydrite is used as the setting modifier in the cement, the slump loss of the concrete will be accelerated, and the early strength component C3A content in the cement is high. If "R" type cement is used, the cement fineness is very fine, and the cement setting time is fast, etc. It will cause the slump loss of concrete to accelerate, and the speed of concrete slump loss is related to the quality and amount of mixed materials in the cement. The C3A content in the cement should be within 4% to 6%. When the content is lower than 4%, the air-entraining and retarder components should be reduced, otherwise the concrete will not solidify for a long time. When the C3A content is higher than 7%, it should be increased. Air-entraining retarder component, otherwise it will cause rapid loss of concrete slump or false setting phenomenon.

The mud content and mud block content of the coarse and fine aggregates used in concrete exceed the standard, and the content of crushed stone needle flake particles exceeds the standard, which will cause the slump loss of concrete to accelerate. If the coarse aggregate has a high water absorption rate, especially the crushed stone used, after being exposed to high temperature in the summer high temperature season, once it is put into the mixer, it will absorb a large amount of water in a short period of time, resulting in accelerated slump loss of the concrete in a short time (30min). 


2 Influence of stirring process

The concrete mixing process also affects the slump loss of concrete. The model of the mixer and the mixing efficiency are related. Therefore, the mixer is required to be regularly repaired and the mixing blades should be replaced regularly. Concrete mixing time should not be less than 30s. If it is less than 30s, the slump of concrete is unstable, resulting in relatively accelerated slump loss.


3 Temperature effects

The effect of temperature on the slump loss of concrete is of particular concern. In hot summer, when the temperature is higher than 25°C or above 30°C, the concrete slump loss will be accelerated by more than 50% compared with that at 20°C. When the temperature is lower than +5°C, the concrete slump loss will be very small or not lost. . Therefore, during the production and construction of pumped concrete, pay close attention to the influence of air temperature on the slump of concrete.

The high use temperature of the raw materials will cause the concrete to increase in temperature and accelerate the slump loss. It is generally required that the concrete discharge temperature should be within 5 ~ 35 ℃, beyond this temperature range, it is necessary to take corresponding technical measures, such as adding cold water, ice water, groundwater to cool down and heat the water and the use temperature of raw materials and so on.

It is generally required that the maximum operating temperature of cement and admixtures should not be higher than 50 °C, and the operating temperature of concrete pumped heating water in winter should not be higher than 40 °C. There is a false coagulation state in the mixer, and it is difficult to get out of the machine or transport it to the site for unloading.

The higher the temperature of the cementitious materials used, the worse the water-reducing effect of the water-reducing components in the pumping agent on concrete plasticization, and the faster the concrete slump loss. The concrete temperature is proportional to the slump loss, and the slump loss can reach about 20-30mm when the concrete increases by 5-10℃.


4 Strength levels

The slump loss of concrete is related to the strength grade of concrete. The slump loss of concrete with high grade is faster than that of low-grade concrete, and the loss of crushed stone concrete is faster than that of pebble concrete. The main reason is that it is related to the amount of cement per unit.


5 Concrete state

Concrete statically loses slump faster than dynamic. In the dynamic state, the concrete is continuously stirred, so that the water-reducing components in the pumping agent cannot fully react with the cement, which hinders the progress of cement hydration, so that the slump loss is small; in the static state, the water-reducing components are fully in contact with the cement, The cement hydration process is accelerated, so the concrete slump loss is accelerated.


6 Transport machinery

The longer the transportation distance and time of the concrete mixer truck, the less free water of the concrete clinker due to chemical reaction, water evaporation, water absorption of the aggregate and other reasons, resulting in the loss of concrete slump over time. The barrel also causes mortar loss, which is also an important cause of concrete slump loss.


7 Pour speed and time

In the process of concrete pouring, the longer the time for the concrete clinker to reach the silo surface, the rapid reduction of free water in the concrete clinker due to chemical reactions, water evaporation, aggregate water absorption and other reasons, resulting in slump loss. , especially when the concrete is exposed on the belt conveyor, the contact area between the surface and the external environment is large, and the water evaporates rapidly, which has the greatest impact on the slump loss of the concrete. According to the actual measurement, when the air temperature is around 25℃, the on-site slump loss of concrete clinker can reach 4cm within half an hour.

Concrete pouring time is different, which is also an important cause of concrete slump loss. The impact is small in the morning and evening, and the impact is greater at noon and afternoon. The temperature in the morning and evening is low, the water evaporation is slow, and the temperature in the afternoon and afternoon is high. The worse the fluidity and cohesion, the more difficult it is to guarantee the quality.


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According to Reuters, U.S. Treasury officials said they would discuss with G7 leaders pricing caps and tariffs on Russian oil as an alternative to the embargo, which would keep the market supplied, limit price spikes, and reduce Russian revenues.  

The EU foreign ministers' meeting was held in Brussels.  The meeting failed to agree on the sixth round of sanctions, including an oil embargo on Russia, because of objections from Hungary.  

EU High Representative for Foreign Affairs and Security Policy said at a press conference after the meeting, that the meeting failed to reach an agreement on the final adoption of the sixth round of sanctions, the permanent representatives of member states to the EU will continue to discuss. The foreign ministers faced similar difficulties trying to reach an agreement on an oil ban. He said Hungary's position was based on economic rather than political concerns.  

Hungary is highly dependent on Russia for energy, getting more than 60 percent of its oil and 85 percent of its natural gas from Russia.  

A few days ago, the European Commission submitted the sixth round of proposed sanctions against Russia, including a total ban on Russian oil imports by the end of this year. Hungary immediately objected and said it wanted substantial compensation from the EU to offset its loss from giving up Russian oil.

The concrete slump price is predicted to increase in the next few days, due to geopolitical factors.

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