Precast concrete staircase

 Precast concrete staircases come in many different varieties, most of which are custom made for each project. The design varies between straight, curved and with a circular spread. The stairs are also made with different surface layers. The most common design is with a terrazzo coating, where separately manufactured steps are placed at the bottom of the form. The stairs are then reinforced and cast with gray concrete. Other surface layers are based on gray concrete where smooth cast is a common variant. The stairs are cast upside down in molds and the step surfaces are cast against the mold. For outdoor stairs, an exposed surface can be created, where the upper cement skin is washed away and part of the ballast is removed. All products are manufactured indoors, which ensures a high and even quality throughout the year. Since each product is custom made new drawings are made before the production process starts. The products are optimized for each project. In this phase of the project, the customer has the opportunity to make choices that affects the entire lifecycle of the building, e.g. reference service life, product dimension etc. Raw materials are purchased and transported to the factory. The raw material that has the biggest impact on the climate is the production of cement. During the production, in the cement factory, a process called calcination is taking place. During the calcination, CO2 is released from the limestone. The finished concrete, however, can retrieve some of this CO2 during its lifetime. Up to 1/5 of the CO2 , which is released during the cement production, can be retrieved by the concrete. This is an important fact to consider when making a life cycle analysis for an entire building. It has not been considered in this EPD since it does not include the end of life perspective. In the factory, a mold is prepared. It can be made of different types of materials such as steel or wood. The reinforcement steel is prepared according to drawing. This means choosing the right quality and dimensions, bending, cutting to correct lengths and binding it together. The concrete is made from aggregate, water, cement and admixtures. It is all mixed in a large concrete mixer. There are different formulas used for different products in order to meet the different needs. After the concrete is poured in to the mold, there is usually a need to vibrate in order to make sure that the concrete fills out the mold and surrounds the reinforcement steel appropriately. Finally, the surface of the product is treated to ensure the correct quality. The product is then covered and left over night to harden. When the mold is removed, the product is inspected to make sure it meets the standards.