Posts in category: Concrete

Concrete cooling systems are crucial for the success of large-pour projects, helping to maintain structural integrity and uniformity in the final hardened concrete. Most concrete cooling systems contain several distinct sections that work in tandem to provide dependable, on-demand flake ice for concrete cooling. Let’s take a look at an important aspect of concrete cooling systems: the flake ice storage unit.

About the Flake Ice Storage Unit

In our past articles in the concrete cooling system we’ve looked at the chilling plant and cold water tank as well as the flake ice plant. After the flake ice is produced in the flake ice plant it travels into the flake ice storage unit where it where remains until it is needed for concrete cooling. This may seem simple, and indeed it is very straightforward; however, there are several key additional pieces of equipment that are usually associated with the flake ice storage unit.

Additional Equipment Associated with the Flake Ice Storage Unit

While different concrete cooling systems may vary and may utilize different equipment and tools in the flake ice storage unit, the typical system is likely to incorporate the following:

Air-Cooling Unit – The air-cooling unit ensures that the temperature within the flake ice storage container remains cold enough to keep the flake ice dry and crisp. Cooling capacity may vary, but usually aim to keep the container at least several degrees below freezing.

Insulated Container Walls – Flake ice storage units are usually very well insulated, often with double-walled insulation. This ensures that even on a hot day, outside warmth stays out and inside cool stays in. A well-insulated container also relieves the burden on the air-cooling unit, allowing it use less energy while still keeping the container at the desired temperature.

Ice Rake – The ice rake repositions the flake ice within the storage container, particularly when locating for discharge.

Screw Conveyor – Many flake ice storage units utilize a screw conveyor for discharging the ice. The screw conveyor is an enclosed tube with a large, rotating screw in the middle. As the screw turns the flake ice is moved.

Blowing System – Rather than a screw conveyor, some flake ice storage units utilize a blowing system to discharge the flake ice. Such systems use moving air to blow the flake ice where it is needed, without prematurely melting it.

SEMCO/SEMCOLD LLC Delivers Quality Flake Ice Storage Systems

The flake ice storage unit is as important as every other aspect of a good concrete cooling system; without a reliable storage unit with reliable equipment and components the flake ice will melt, clump together, or fail to discharge, rendering it useless. SEMCO/SEMCOLD LLC provides high quality, dependable flake ice storage systems and concrete cooling systems. Our systems are fully customizable, allowing our clients to get the features and equipment they need most for their large-pour projects.

Concrete cooling is a crucial component of many large-pour projects in order ensure the quality and structural integrity of the resulting cement. Thus a concrete cooling system with various distinct, integral parts is likely to be in place for these large-pour projects. One such integral part of successful concrete cooling systems is the flake ice plant. Let’s take a look at how the flake ice plant works and what benefits it offers for concrete cooling.

About the Flake Ice Plant

For most concrete cooling system, cold water from the water chilling plant and cold water tank makes its way into the flake ice plant. This cold water is then sprayed onto the surface of refrigerated drums that are so cold that the water freezes instantly into ice. In fact the drums are so cold that the ice is often sub-cooled to below freezing. After the ice has formed ice removal tools then shear the ice away from the drum in a very thin layer, forming flakes. The flake ice then falls into special refrigerated storage containers where it can then be taken to chill the concrete during pouring.

Why Flake Ice?

There are of course almost limitless shapes and sizes into which ice can be frozen and tube ice, plate ice, shell ice, and crushed ice are all also popular ice types in a wide array of different industrial and commercial applications. That thus raises the question, why flake ice for concrete cooling systems? Flake ice has many major benefits including the following:

The Benefits of Flake Ice

• Flake ice has a greater surface area per unit of ice than any other ice type. This allows it to have a higher cooling efficiency compared to other ice types.
• Flake ice is able to flow well and does not clump or stick together into blocks or chunks, thus allowing it to be used more easily without blockage and also allowing it to maintain its cooling efficiency and relative high surface area.
• Since flake ice is often sub-cooled it is able to utilize a 100%, or even more, of its latent heat cooling energy.
• Because flake ice is so small it has a very short melting time, thus leading to quicker mixing times since the ice needs to melt completely in the concrete.
• The shorter mixing times made possible by flake ice also result in less strain on mixing equipment, thereby increasing service life and lowering costs.
• The dryness of the sub-cooled flake ice allows for accurate calculation of its cooling input and also quickly reveals its effects on the mixture temperature.
• Flake ice can be conveniently stored and works well with automated ice rake systems.
• Flake ice can be easily transported where it is needed, often using blowing systems or screw conveyors.
• Because the flake ice is sheared from the drum rather than loosened with hot gases there is no energy loss.

The Benefits of Sub-Cooling

Many of the benefits of flake ice discussed above are facilitated or enhanced by sub-cooling. Sub-cooling involves lowering the ice temperature to below freezing. The advantage of this is that the flake ice will not melt prematurely as it is handled and will thus remain dry, crisp, and easier to work with. This also ensures that all of its cooling potential will be able to be put to use in the cement mixture where it is needed.

SEMCO/SEMCOLD LLC Provides Dependable Custom Flake Ice Plants

SEMCO/SEMCOLD LLC provides custom-built concrete cooling systems that are designed to best fit the needs of the particular client and project. We can customize the flake ice plant to provide different capacities of daily flake ice production and will optimize the system to best suit the cooling temperature and water cooling capacity requirements of your cement pour operations. For more information about concrete cooling systems be sure to check out the other articles in this series and as always please contact SEMCO/SEMCOLD LLC so that we can design an outstanding concrete cooling system for your company.

As discussed in our article about Why Concrete Cooling is Necessary there are several important reasons why cooling concrete is beneficial, particularly in relation to improving its strength and durability. Thus for optimal results many large-pour cement projects require a comprehensive concrete cooling system. The exact specifics of the concrete cooling system will of course vary somewhat depending on the particular application and needs of the project. However, what follows is a general overview of the main components likely to be found in most concrete cooling systems.

Water Chilling Plant

The temperature of the water used in cement hydration is one of the single most important factors in determining the concrete’s temperature. Thus using well-chilled, cool water is an effective concrete-cooling strategy and most concrete cooling systems utilize a water chilling plant. The water chilling plant is a water cooling system designed to lower water temperature from its natural environmental temperature often to near freezing levels.

The water chilling plant itself is likely to contain various pieces of equipment which may vary somewhat depending on the particular system. Common components include compressors, a gauge and control panel, pumps, evaporative condensers, and heat exchangers. The efficiency of the system may vary, but strides have been made in making modern water chilling plants much more power efficient than older plants.

Cold Water Tank

Once the water has been chilled in the water chilling plant it will need to be stored in an insulated tank to maintain its cold temperature. The tank will of course have a pump for circulating the water into and out of other parts of the cooling system. Cold water tanks may themselves be made of concrete or they may be made of steel or other materials. The size of the tank will typically vary depending on the requirements of the cooling system. In all cases it is important that the tank be well insulated to prevent the water from warming up again.

Ice Plant

In addition to cooling the water used in cement hydration, another common and effective strategy for concrete cooling is to add ice, particularly flake ice, into the mixing drum to further lower the concrete’s temperature. Flake ice is an especially good type of ice to use for this application because its small size and high relative surface area ensure that it will pack the most cooling punch while still melting quickly and thoroughly. Rapid melting is important because the cement mixture needs to be uniform.

Thus, the ice plant is responsible for making the ice that will be used in the cooling process. Ice production generally takes place in a refrigerated drum. Water is sprayed onto the drum’s surface where it will freeze almost immediately. Next an ice removal tool will shear the ice off the drum’s surface, allowing it to fall into a storage bin. For the best cooling properties the ice should be relatively thin, roughly about 1.5mm thick. Good ice plants will also make ice that remains crisp and does not stick together or clump into blocks, will melt rapidly, and that is easy to convey to the blowing system.

Ice Storage Bin

Just as the cold water tank holds the chilled water that leaves the water chilling plant the ice storage bin houses the completed flake ice. It is crucial that the ice storage bin be well-insulated and many are thus double-walled. Some systems also include an air-cooling unit designed to keep air temperatures low and prevent the ice from melting. A good ice storage bin will keep the flake ice crisp and maintain its cooling integrity. Just as the cold water tank comes in various sizes to fit the needs of the project, so too are different capacity ice storage bins available.

Ice Delivery and Weighing

The ice delivery and weighing component of the concrete cooling system plays an important role in delivering the correct amount of ice to the mixing drum and batcher plant. It must also do so in a consistent, reliable way that does not freeze up or compromise the integrity of the ice. Typically the ice delivery system will utilize a blower, rotary valve, and cyclone receiver.

Aggregate Cooling With Water

For many concrete cooling projects chilling the mixing water and adding flake ice to the mixer will be enough to sufficiently cool the concrete. However for other projects the application calls for such significantly cooled concrete that it is also necessary to cool the cement aggregates. One effective method is with the use of chilled water. The cooling rate of the aggregate will depend in large part on the size of the aggregate, as well as on the temperature of the water. Depending on these factors exposure to water may accomplish the necessary aggregate chilling in as little as one minute to as long as an half hour or more.

Two methods of aggregate cooling with water include wet belt applications and flooded aggregate silos. With wet belt applications the aggregates are placed on moving conveyor belts and then flooded with chilled water. With the flooded silo method the aggregate silo itself is completely flooded with chilled water. Both methods require a sediment basin and de-watering system to re-separate the water from the aggregates.

Aggregate Cooling With Air

Water cooling the aggregate is an extremely effective method; however, it requires more space to accomplish since it necessitates the use of a de-watering system. Thus for projects with limited space, air cooling of the aggregates may be more desirable. This process involves blowing cool air in a continuous stream through the aggregate silo. Typically the aggregates will be slightly moistened since evaporative cooling holds much greater cooling potential. However, since the moisture is evaporated no net moisture is added to the aggregates.

Other Cooling Systems: Sand Cooling & Post-Cooling

For some projects that need extremely thoroughly cooled concrete they may utilize another cooling method in addition to chilled water, ice, and aggregate cooling: sand cooling. Sand cooling is a much more demanding process that will generally require custom-designed systems specialized to meet the needs of the particular project.

A final option is a post-cooling systems that runs chilled water through a network of pipes throughout the concrete. This process may be used in dam construction to allow for very thorough cooling. These final two options are not as common as other components of a concrete cooling system.

SEMCO/SEMCOLD LLC builds and delivers reliable, efficient concrete cooling systems that are custom-designed for each of our clients with their cooling needs and capacity demands in mind. No matter the size of the project we will create a state-of-the-art concrete cooling system that will get the job done.

In previous articles we have discussed the importance of concrete cooling and why it is an essential part of many large-pour projects. We have also reviewed an overview of a typical concrete cooling system. In today’s concrete cooling article we will examine one of the most influential aspects of a concrete cooling system: the cold water system. This includes the water chilling plant and the cold water tank.

Why Is the Cold Water System Important?

The temperature of the water used for mixing concrete is the single biggest determiner of the temperature of the concrete, outweighing even the aggregate temperature and reducing the burden placed on the ice system. Fortunately the temperature of the water being used can easily and effectively be controlled by the pouring company as long as they utilize a quality water chilling plant and cold water tank. This makes cold water systems an almost universal aspect of most concrete cooling systems.

The Water Chilling Plant

The water chilling plant is the part of the cold water system that cools the water from its beginning ambient temperature down to almost freezing levels. Many water chilling plants are able to reduce water from a starting temperature of 113°F all the way down to about 33°F or 34°F, a massive 80°F differential! Although naturally the lower the starting temperature of the water, the more quickly and efficiently the water chilling plant can operate, thereby reducing cooling load costs and saving time.

There are different water-chilling systems on the market which may vary slightly in terms of the temperatures they can process and the exact processes by which they achieve them. Typically the system will utilize evaporative condensers, compressors, and heat exchangers, with some systems featuring multiple compressors or heat exchangers for maximum cooling potential. In addition to these system components the water chilling system will also likely feature a control panel and gauges to monitor and regulate water temperatures, and of course water pumps to convey water into, throughout, and out of the system as needed. Technology has advanced over the years, making modern water cooling systems more efficient and effective than older systems.

The Cold Water Tank

As the name implies, the cold water tank is used to store the cold water after it is chilled by the water chilling plant. The tank is insulated to help maintain the water temperature. The tank will also feature a pump for circulating water into and out of the tank and into other parts of the system. The size of the tank may vary depending on the specifications of the system.

Some cold water tanks may consist of concrete and be insulated on-site, which has the advantage of allowing the tank to be any size as needed. Other tanks may consist of steel with insulation and are usually only available in specific sizes.

Most cold water tanks are installed directly below the water chilling plant. This is an effective way for the water to flow from the water chilling plant into the cold water tank, and also helps utilize space more efficiently. SEMCO/SEMCOLD LLC is proud to manufacture and install industry-leading cold water tanks and water chilling systems for the concrete cooling sector. Our systems can be customized to best fit the particular needs of each our clients.

Companies having concrete work done may have heard the term ‘concrete cooling’ used before. For some people who are unfamiliar with the concrete industry this term may have seemed confusing or surprising. Many people may have been left wondering why concrete cooling was necessary at all. Below is a discussion of why concrete cooling is important, what problems can arise from concrete that is too hot, which projects may be most in need of cooled concrete, and what factors can influence concrete temperature.

The Chemistry of Concrete

Though in casual conversation some people may use the terms “concrete” and “cement” interchangeably, it is important to understand the distinction. Cement is the mixture that, when combined with water, forms the material known as concrete. Concrete formation itself is accomplished through a process known as cement hydration. This essentially refers to the chemical bonding of cement aggregates with water. Concrete cannot harden and strengthen without hydration.

All chemical processes can be classified as either endothermic, meaning they absorb heat and thus lower the temperature of their surroundings, or exothermic, meaning they release heat and thus raise the temperature of their surroundings. The process of cement hydration involves mostly exothermic chemical reactions. Thus as hydration occurs the concrete gets hotter. In some applications concrete temperatures may exceed 200°F.

Problems Associated with Hot Concrete

As concrete hardens the process is known as curing. Unfortunately high curing temperatures for concrete can result in reduced tensile strength and performance. It is well documented that concrete that cures at temperatures of 95°F or higher will have significantly less strength than concrete that is cured at around 70°F.

Part of the problem is that concrete that is curing will expand at higher temperatures. This results in a less dense setting, thereby reducing the strength of the concrete. This is especially a problem in large-pour settings where the inner concrete may be significantly warmer than the outer concrete, sometimes by as much as 10-20°F, resulting in non-uniform density and weak spots.

Another problem associated with hot concrete is related to water evaporation. As most people are well aware, water evaporation occurs much more quickly at higher temperatures than at lower temperatures. Thus as the temperature of the concrete rises, more and more water is evaporated. Unfortunately since the process of cement hydration relies on water this can create serious problems and may prevent some of the cement from ever fully hydrating.

Industrial Applications Are Particularly Vulnerable to High Concrete Temperatures

Industrial settings are among the most vulnerable to problems associated with high concrete temperatures. This is because industrial settings often require large-pour applications, which as discussed above often results in higher concrete temperatures and potentially non-uniform density and reduced tensile strength and performance. Another reason that industrial settings are particularly vulnerable to strength problems associated with high concrete temperatures is because industrial settings require very strong concrete to begin with. Thus any weakness could prove catastrophic in an industrial setting, whereas in lower-demand settings it may not prove problematic. In industrial settings often the safety and integrity of the entire facility is dependent on the performance and strength of its concrete.

Factors That Affect Concrete Temperature

The temperature of concrete is most significantly affected by the water used in the hydration process. Thus concrete cooling methods often involve cooling the mixing water prior to hydration. However, the temperature of the cement aggregates is also important and by pre-cooling the aggregates lower hydration temperatures can also be achieved. Another method of concrete cooling is drum cooling, which involves cooling the concrete mixtures as it hydrates. Naturally many concrete cooling systems involve using these techniques in conjunction with each other for maximum performance.

SEMCO/SEMCOLD LLC is an industry leader in providing industrial cooling systems, including for the purpose of cooling concrete. Our systems can be fully customized based on the particular needs and preferences of each of our clients. Please contact us for more information about concrete cooling.