In the current building construction practice, flat plate is the most common floor structural system due to its economic and practical advantages. Traditionally, high material costs have had a great impact on total construction cost, so voided options as ribbed or waffle slab have been used extensively. However, recently there is a tendency to design solid slabs options, especially due to rising labor costs, simpler and quicker construction, which reduces execution timeframe and increases construction safety.

The use of post-tensioned (PT) floors in building structures has been growing in recent years. This type of construction allows thinner slabs and thus, it creates lighter structures, produces a large reduction in rebar tonnage, with the subsequent advantages in transportation, storage or labor. Also, these slabs have other advantages as reduced cracking and deflections, reduced floor to floor height or quick construction. In most countries these design mechanical and economical features have enabled the system to compete economically with traditional in-situ concrete floor slabs; however, this is not the case in some other countries like Spain. Introduction of sustainability criteria and specialization in construction can allow for this system to be introduced in the market, which can also mean lower costs, improved performance and focusing on sustainability in construction.

Different solutions have been studied for an actual project, in terms of material quantities, minimum structural thickness and it has also been checked the impact of costs and environmental criteria based on CO2 emission. With these data, we could assess that the current status of low production of flat slabs in Spain it is not related to real economic reasons; it is actually related to a combination of reasons as lack of technical knowledge of designers or builders, inconsistencies or deficiencies in current national codes in each country. The construction industry is following an inertial period that resists changing known systems, apparently satisfactory, and that especially shows an unsustainable view of the construction. Post-tensioned concrete slabs will not always be the most suitable and sustainable option, but it should be evaluated while considering other more familiar techniques of construction with updated considerations.

Reference:

” Evolution and sustainability of in-situ concrete flat slabs in buildings”

Liébana, O.; G. Pulido, MD; Gómez Hermoso J. 

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