10 Myths When Working With Concrete Paver Molds

Myths and misconceptions are widespread in the concrete business. Having appeared once, the myth begins to live its own life, people believe in it and repeat it. In this article, we will expose the most popular misconceptions that rule the world of concrete paver molds construction.

Myth # 1:

The addition of water to the concrete mix leads to an increase in a slump.

Actually:

There are other equally effective ways to increase concrete slump besides adding water.

Adding too much water directly on site increases concrete slump. The addition of excessive water directly on site increases concrete slump, but also significantly reduces the strength of the concrete structure. The added water dilutes the concrete mix and increases the water to binder ratio. Too much water also reduces the resistance of the concrete to freeze and thaw cycles, increases drying settlement, and results in problems with building maintenance later on.

The workability of the concrete mixture and other mortars is one of their most important qualities. An increase in water consumption is not an option, because this decreases the strength of the cement. An increase in cement consumption in concrete with a constant water content does not affect the workability of the concrete. The ratio of cement paste and aggregate plays a role; with an increase in the amount of cement mixture, concrete becomes more workable, while the strength of concrete remains unchanged.

Many technical requirements prohibit the addition of water to concrete at a construction site. However, there are other ways to improve the slump and workability of concrete. The quality of aggregates (crushed stone and gravel), their maximum size affects the consumption of cement and water, affects the mixing process. Reducing the amount of water and plasticizers can also be used to increase slump while maintaining the water to cement ratio, and the amount of air entrained affects the processability of the concrete. The addition of water that contains chemical additives can change the quality of the mix and cause a loss of mobility of the concrete mix and the composition of the air inside the concrete.

Myth number 2:

Determination of the grade of concrete by the number of bags of cement

Actually:

The proportions of the mixture are determined according to technical requirements, and not by the amount of cement. “How many bags of cement do you need per cube of concrete?” – one of the most popular questions for concreting specialists.

However, quality is not measured in the number of bags. As a rule, cement is delivered to the construction site in 50 kg bags, and sometimes it does not meet the required standard. The proportions of cement in the mix depend on what you are building. For a reasonable consumption of cement, in order to avoid loss of fluidity of the mixture, shrinkage, as well as compliance with the temperature regime, excess concrete paver molds cement should be avoided. In specifications, a minimum amount of cement is often specified to increase the durability of the concrete, the suitability of fresh concrete for finishing, and improve the wear resistance and appearance of the surface. The most important part in the selection of concrete proportions is the ratio of water to aggregates and binders.

Myth number 3:

Concrete waterproof

Actually:

Even the strongest concrete has a porous structure.

Concrete has a porous concrete paver molds structure. Water and other substances in a liquid or vapor state can pass through concrete. Depending on the porosity of the concrete, this process can take from several minutes to several months. To increase the waterproofing of concrete, cementitious chemical additives such as pasteurizers, hydrophobic cement, and additional cementitious additives such as silica and fly ash are added to it. Also, you can treat the surface of the concrete with hermetic materials.

Myth number 4:

The harder the concrete, the more durable it is.

Actually:

Compressive strength is not the only determinant of concrete durability.

While compressive concrete paver molds strength is an important property of concrete, other properties can further affect the durability of concrete in harsh environments. In general, the main causes of concrete aging are:

• reinforcement corrosion
• exposure to freeze-thaw cycles
• alkali-oxidative reactions
• low sulfate resistance

Reducing the permeability of concrete is the key to its durability.

Myth number 5:

“Let’s add calcium chloride – so that the water does not freeze”

Actually:

Calcium chloride is a concrete hardening accelerator, not an antifreeze agent.

The presence of calcium chloride, at the initial stage of preparing the concrete mixture, increases the setting (hydration) rate by one and a half to two times. However, fresh concrete needs frost protection until it reaches minimum strength. Without such protection, concrete will freeze and then be less durable. To avoid problems when pouring concrete in cold weather, make sure the temperature of the concrete is kept within the correct range.