Concrete Contractors Colorado Springs is so ubiquitous that we often don’t consider it a material. But it is powerful, durable, and versatile. No other material exemplifies the transformation of culture into economy as much as concrete. It spawned brutalist structures but also helped create the sleek, modernist buildings of Le Corbusier and Oscar Niemeyer.
Concrete combines coarse and fine aggregates, mineral admixtures, water, cement paste, and sometimes fly ash. The cement serves as a binder, holding the other ingredients together. It also hardens to become a strong and durable material when it dries. In construction, it is poured into forms to create structures such as walls, floors, and roads. Getting the mix right before rushing is important to ensure a good result.
The mixing process is done either by hand or with machine. Hand mixing involves placing dry ingredients on a flat surface and adding water to form fresh concrete. Machine mixing is usually more efficient for larger productions, allowing the concrete to be discharged quickly.
Once the concrete is mixed, it must be transported to the construction site where it will be used. This can be accomplished in various ways depending on the quantity needed, the distances involved, and other project specifics. Large amounts are often transported by truck or poured out of a mixer into formwork for structural elements. Smaller quantities can be carried in a wheelbarrow, bucket, or toggle bag.
A quick field test to determine the consistency of concrete is to pick up a handful and squeeze it tightly. If the concrete is properly mixed, it will hold its shape and not crumble under pressure.
It is also important to note that concrete should be mixed for the correct duration. A long mixing time will lead to poor results. It is suggested that the proper mix should be aerated for 3 minutes to make sure all ingredients are evenly combined. Then, the concrete should be left to rest for 1 minute before checking again.
Some concrete producers have determined the proper mixing time by performing lab tests on cylinders and cubes. This process is called mix design and helps find the best proportions for a desired strength. Other researchers have tried to measure the homogeneity of concrete by analyzing the distribution of various solid constituents in the concrete as it was discharged from the mixer. Johansson found that a concrete mixture’s uniformity increased with the mixing duration up to a point and reached a plateau (see Fig. 5.2).
Concrete is one of the most indispensable building materials, and to make it last long, it needs to be placed correctly. In addition to ensuring that the mix is properly designed, batched, mixed, and transported, the site preparation process, formwork, and reinforcement placement are crucial to the success of a project.
During the preparation process, the job site must be cleared of obstructions, excavation work must be done to create a suitable foundation, grading and stabilizing the soil, and utilities and services must be connected to prepare for construction. Once these steps have been taken, the concrete can be placed.
Once the concrete has been mixed, it is pumped to the desired location on the job site in a controlled manner. Using the right equipment can help ensure that concrete is properly placed and there are no problems in this process. This is especially important if you are working on a large-scale concrete project that requires multiple substantial lifts to be placed quickly.
The equipment that is used to place concrete should be able to ensure that there is a virtually continuous flow during depositing without segregation of the different concrete ingredients. Ideally, the concrete should be placed in successive horizontal layers that are uniform in thickness and deposited before the previous layer stiffens to avoid the formation of cold joints or planes of weakness. It is also important to use efficient communication between the concrete pump operator and the team that is placing the concrete to prevent any mishaps that could compromise the quality of the finished product.
Once the concrete has been deposited, it is usually compacted mechanically to eliminate any entrapped air voids and ensure intimate, complete contact with the forms and reinforcement. Most concrete is now consolidated by the use of a powered internal vibrator, which can be adjusted to match the slump of the particular mix to minimize the amount of desirable entrained air that is lost during the consolidation process. For thin slabs, however, a mechanical surface vibrator may be more effective since it can be placed directly against the formwork and reinforcement.
The curing process gives concrete strength, durability, and long life. Curing occurs after concrete placement and finishing and involves maintaining the desired moisture and temperature conditions throughout the substantial section depth for extended periods. It also protects the concrete from environmental factors such as wind, sun, and rainfall that can influence surface hydration and thermal cracking.
The main function of curing is to maintain adequate water content in the concrete-section depth and to control the water loss from the surface of the concrete that can cause plastic shrinkage cracks. Curing is especially important in areas with high sunshine exposure or large surfaces compared to the depth, such as roads and airport pavements, canal linings, bridge decks, and cooling towers.
There are many ways to cure concrete, and each has its advantages. The most common methods include water, membrane, and insulating blanket curing. Water curing uses sprayers or sprinklers to moisten the concrete and prevent evaporation. Membrane curing uses a liquid membrane such as bitumen emulsion, rubber latex emulsion, or wax to form an effective barrier against water vapor. Insulating blanket curing is an economical way to maintain the moisture in concrete and reduce drying.
In addition to maintaining a constant moisture level, the concrete must be kept at a constant temperature throughout the concrete-section depth. This is crucial because the chemical reaction that forms the concrete is an exothermic process that produces heat. If the concrete gets too cold, the hydration process slows and may not occur at all. On the other hand, if the concrete becomes too hot, it can develop stress cracks because the hydration cannot keep up with the strain being applied to it.
Properly cured concrete is strong, durable, and resistant to abrasion, freezing, thawing, and deterioration from carbon dioxide, chloride, and other chemicals. Engineers and architects often specify a minimum seven-day curing period in concrete structures, such as slabs on grade, driveways, sidewalks, and foundations. This is important in ensuring the concrete meets the design requirements and withstands the intended loads.
Concrete is a very durable material that can withstand immense amounts of force. It is also one of the most widely used materials in construction because it can withstand harsh conditions like extreme weather and blazing fires. It can also be easily molded into several different shapes and sizes, making constructing large structures like tunnels, bridges, high-rise buildings, dams, and other infrastructure easy.
Although strong, it needs proper reinforcements to ensure its structural integrity is not compromised over time. Choosing the right type and percentage of reinforcements is important because it will have a significant effect on how much load can be resisted by the concrete. Reinforcement is added to the concrete during the mixing process, and it can also be incorporated in situ using a formwork or poured into place with a tremie or other equipment.
After the concrete has been poured, it must be allowed to cure for a specified amount of time. During this time, it must be protected from water and extreme heat. This is done because heat and wind can dry out the moisture necessary for hydration to occur, which will affect the concrete’s strength development. It is also important to prevent freezing because this can damage the crystalline structure of the hydrated cement paste.
The curing process can be made more efficient with the help of several additives. Air entraining agents are often used to add and entrap tiny air bubbles in the concrete, which can reduce damage caused by freeze-thaw cycles. These additives can reduce the time it takes for concrete to reach a satisfactory strength level, which is a critical factor in its durability.
Crystalline admixtures can be added to concrete during mixing to lower its permeability. These additives can fill capillary pores and micro-cracks to block pathways for water and waterborne contaminants. They can also create a permanent waterproof barrier by crystallizing to seal the surface of the concrete. Finally, pigments can be added to the concrete during mixing to change color.