Precast concrete parts

Concrete components are produced with the so-called formwork as a hollow form. Concrete formwork usually consists of a formlining and formwork system. The fresh concrete is left in the formwork until the concrete has completely hardened, after which the formwork can be removed. For this process, which is called stripping, a certain stripping time must be observed, which varies depending on temperature conditions, material and load. The waiting time before stripping can be five minutes, but it can also take up to 28 days. Until then, the formwork and counter formwork are held together by a form tie to prevent the fresh concrete from coming loose prematurely. The formwork ties also specify the shape and thickness of a component.

The formwork for precast concrete elements is used in many different ways in the construction sector. Each individual formwork type has its advantages and disadvantages and its specific areas of application. The formwork is selected in each case depending on the function and type of construction project. The formwork plays a major role in determining the structure of the surface of the component. Knowledge and experience in handling the products and precise planning are essential in this project.

A formwork construction consists of various formwork elements. This includes a formwork skin, a structure for support, a bracing structure, lanyards and various accessories. B.T. innovation offers you the ideal solution for your fastening problem with the extensive magnet program. In order to support the load of the fresh concrete without causing deformations and inaccuracies, the formwork must have sufficient stability and rigidity. The formlining shapes the surface structure of the concrete part. Therefore, a clean production area is essential for impeccable precast concrete products.

In order to achieve optimum stripping of the precast elements, the precast concrete worker ensures that the precast element and the formwork are easily detachable by pretreating them with release agents. Depending on the type of formwork, oils, waxes, varnishes or emulsions are used. The so-called formwork oil is mainly used for exposed concrete , but also when the formlining is to be used several times. The formwork material can be concrete, plastic, steel, hardboard or wood. Extreme care is required in the production of each formwork, as the fully hardened elements can no longer be checked before the formlining is released.

Another challenge when using precast concrete is sealing the finished product to make it resistant to water under pressure. B.T. innovation offers you the right solution for any sealing problem, thanks to the multifunctional Elast systems. Find out more about sealing technology.

The assembly of the prefabricated building elements on site used to represent an enormous effort. B.T. innovation offers the optimal solution for connecting precast concrete elements: With BT turnbuckle® , construction elements are connected to each other in a cost- and time-saving way.

Basically, precast elements are components made of reinforced concrete, prestressed concrete or conventional concrete, which do not harden at their final destination but are first manufactured in a precast plant. Precast concrete elements are laid later from the precast concrete plant and installed accordingly at their place of use.

Covered areas protect the building materials from the weather and allow them to cure evenly at a room temperature of at least +5°C under homogeneous production conditions. Due to the consistent manufacturing conditions, the precast concrete part produced in the concrete plant can convince with a high quality.

Steel reinforcements embedded in the concrete help to provide better resistance to the tensile or compressive forces acting on the concrete. The reinforcement of a precast concrete element must meet the same requirements as the reinforcement of solid concrete.

Types precast parts

• Double walls – These prefabricated concrete elements consist of two concrete slabs and are used to build concrete walls. Properly positioned on the site, the walls must be filled with fresh concrete and create concrete walls according to plan, saving time due to the lack of formwork. B.T. innovation offers MagSwing, an easy-to-use formwork system for double walls.

• Prestressed slabs – The prestressed slab is mostly used in larger structures. With the help of prestressing, high spans of these ceiling systems are achieved. When support is not possible for large loads over wide spans, prestressed slabs should be used.
• Bridge girders – In order to avoid difficult formwork work over bodies of water, prefabricated concrete elements are usually used in bridge construction. An advantage is the shorter time required for construction, but a disadvantage is the greater transport effort.
• Stairs – Stair treads require a considerable amount of formwork and are therefore usually not formed directly on site but in the factory. Precast concrete elements offer a good alternative here and savings of time and therefore money.
• Beams and columns – beams and columns are mainly used in large structures, as they significantly reduce labor time and construction costs.
• Element slab – The element slab is assembled from several concrete surface elements on site and, if necessary, supplemented with in-situ concrete.

The conditions and prerequisites of each construction project differ and so it must be fundamentally examined which concreting method and which products are the more economical variants for the individual construction. In some cases, cast-in-place concrete or a combination of precast concrete and masonry may also be the more appropriate option (join concrete). Since concrete plants are the production site of precast concrete parts, the part must first be transported to the installation site fully hardened and can be properly positioned there with the help of the respective lifting equipment. Apart from the precast plant, precast elements can also be concreted on site and then installed at the point of use.
Excessive formwork for cast-in-place concrete may lead to the decision to use precast.