Too much entrained air will have major detrimental consequences on the concrete's performance, such as loss of strength and stickiness during finishing. Air entrainment should not be employed in steel troweled interior concrete, especially machine troweled interior concrete. The steel used for interior flooring materials is very thin and would get damaged if too much air were incorporated.
The best method for determining whether or not your concrete needs to be air-entrained is with a concrete testing kit. These kits contain instruments that are used to measure various properties of fresh and hardened concrete. The tests performed by these instruments help determine how much air is present in the concrete and what type of reinforcement is needed based on your project requirements.
If you decide to air-entrain your concrete, there are several methods available. The two most common methods are dry-blending and wet-blending. Dry-blending involves the use of an air-entraining additive that is mixed into the cement mix before it is poured. This allows for better control of the amount of air introduced into the concrete. Wet-blending requires the addition of water to the cement mix before it is poured to create a slurry that can be stirred into place. With this method, less attention needs to be paid to ensuring that enough air-entraining additive is added to the concrete.
Overmixing concrete reduces the quality of the concrete, grinds the aggregate into smaller pieces, raises the temperature of the mix, reduces the slump, reduces air entrainment, and reduces the strength of the concrete. Overmixing also causes unnecessary wear on the transit mixer's drum and blades. Concrete that is overmixed requires more water to achieve a proper consistency and increases the amount of time it takes to harden.
As long as you don't exceed the recommended dose of admixtures, concrete can be overmixed. Excessive roller traffic can also overwork the concrete, causing it to appear dull and gray instead of white or light brown. If this happens, stop mixing for a few days until the color returns to normal.
Concrete that is overmixed may look clean when first poured but will soon become dry and dusty inside your garage, basement, or other area where it cannot be exposed to sunlight. The only cure for overmixed concrete is to remove it and start over with fresh ingredients. There are several ways to do this including grinding up old concrete to use as aggregate for new batches or simply adding more water if the mixture appears too dry.
If you overmix concrete, you need to add more water so that the mixture reaches its desired consistency. This is called "slumping" the concrete. When slumping concrete, it is important not to add too much water, otherwise, the cement will not set properly.
Aircrete does not have the same strength as concrete. It has half the strength of normal concrete. Unlike concrete, which includes elements that make it thick, aircrete infuses air bubbles or styrofoam beads into the concrete to make it less dense and lighter. The foam adds weight but not much else in terms of strength.
Concrete is a composite material made up of coarse grains (sand or gravel) used as a binding agent for finer grains (gravel, cement, water), with or without additives such as plasticizers or fibers. As a result, it is stronger than any single element.
Aircrete is similar to foam concrete, except that air is substituted for the foaming agent used in traditional concrete. Aircrete is used primarily for decorative purposes or when a concrete block needs to be light-weight.
Decorative airconctites include sand mixed with polymer particles and colored pigments. These products can be molded into various shapes and designs before they set. After setting, they can hold their shape indefinitely if left alone. They can also be painted to create different colors and textures.
Light-weight airconctites are used to make concrete blocks or other concrete products that need to be light yet still have adequate strength. Blocks made from this type of concrete will not have full strength until they are completely hardened.
Fresh concrete stiffens with time and loses workability, but it is not settling or developing strength. Some water is absorbed by aggregate after mixing concrete, some is lost by evaporation, and some is needed for first chemical reactions. The loss of workability over time is caused by a variety of circumstances, including:
As concrete cures (hardens), the fluidity of the mix decreases due to the formation of an expansive crystalline mass that breaks down over time under stress. This means that you will need more water than normal when casting fresh concrete to get it into the right state for workability.
Concrete also absorbs water from the atmosphere in form of vapor pressure. This occurs especially during warm seasons or when it rains before it has time to dry out. As long as there is still water in the mix, the concrete will absorb more until it reaches its maximum absorption level. At this point, additional water poured on top of the mixture will not go further than that which has already been absorbed, so no new areas of the surface are reached by the water.
Finally, concrete loses its workability over time due to the action of enzymes called "curing agents" that are added to accelerate the setting process. These chemicals reduce the viscosity of the mix and allow it to be mixed more easily. However, they can also cause skin irritation if not used properly.