Some precast floor systems are ready to lift in place. Filigree slabs are different — and that’s by design. They are delivered as a thin precast base layer, lifted into place and only become a completed structural concrete floor when site poured concrete is poured over them, permanently bonding to the precast layer below. That composite solution brings a unique set of benefits to filigree slabs when compared to other precast flooring types – and a real filigree slabs solution to the UAE market. This guide explains the nature of precast concrete filigree slabs in UAE, the composite system, the things to consider before selecting a supplier, and the manufacturing process up to the final product – a filigree floor.
What a Filigree Slab Is and Why It’s Used
A filigree slab, also called a “Filigran” slab (from German engineering), is a precast concrete slab that is generally 5 to 7 centimetres thick, and includes bending-resistant reinforcement or lattices that are cast up from the top surface. The precast base is then lifted onto site, and a layer of ready mixed concrete is poured over it subsequently, securing the base firmly in place with the structure of the concrete that is poured, so that on curing, this base is structurally united with the exposed reinforcement to form one monolithic composite floor.
This hybrid system, which involves a factory-cast base with a topping cast on site, offers filigree slabs some unique benefits over all precast systems, such as hollow core. The precast base acts as permanent formwork, eliminating the need for temporary shuttering on-site, while the exposed lattice girders allow the site concrete to bond seamlessly, structurally behaving the same way a conventional cast-in-place column, beam and slab connection would. This is especially useful for projects where flexibility in design for non-standard openings, shapes, or architectural elements, would be more difficult to achieve with a fully precast system – as changes to the system once cast are possible with the site-poured topping.
The UAE, in particular, has carved out a niche for itself among CAD/CAM-manufactured precast elements with computer-controlled production processes reducing manufacturing error and enabling the elements to be manufactured in the shape that modern architecture demands.
Types of Filigree Precast Elements Available in the UAE
There are different types of filigree precast elements available in the UAE.
Filigree is not restricted to floor slabs as the same composite concept is applied in the various related precast products.
Filigree Floor Slabs
The core product: a thin precast base with exposed lattice reinforcement, topped with concrete at site to make a complete structural floor, on residential, commercial and institutional building projects.
Filigree Double Wall Systems
The same concept was attempted to be applied to vertical elements, in the form of two thin precast concrete leaves, fastened together with lattice girders, delivered as a single unit, and filled with site-poured concrete between the leaves, which will make a solid, structural wall upon curing.
Filigree Stairs
Manufactured following the same high precision CAD/CAM levels the stair elements are of good surface quality, have accurate dimensions and — crucially — are crack-free and do not need screeding, giving immediate access to the floor levels and allowing direct application of paint after installation.
Benefits of the Filigree System for UAE Projects
In addition to the composite structural principle itself, filigree has some practical advantages that are relevant in actual construction projects in the UAE.
Reduced Site Time
The precast element can also substantially shorten the overall project time because it can serve as permanent formwork and save on-site labour in reinforcement fixing time, figures in the industry put that at around 20 per cent compared to the conventional cast in place method.
No Screed Required
The accuracy of factory made filigree also means that the finishing is of such a high standard that a separate screed layer is not required, thereby saving secondary trade costs and time in having to lay the screed afterwards.
Design Flexibility
The flexibility of filigree over other completely precast systems is found when the final structural floor or wall requires non-standard shapes, openings, and architectural detailing elements, but retains the quick construction time of off-site production.
Minimize Waste Material and Hazardous Working Environments
Less on-site formwork and reinforcement fixing will lead to less construction waste and a generally safer working environment, because most of the labour intensive work takes place in a controlled factory environment rather than at height on site.
Factors to Consider When Choosing a Filigree Slab Supplier in UAE
There are some factors to consider when choosing a Filigree slab supplier in UAE.
Filigree is a more specialised precast system than hollow core or solid slabs, and therefore this does entail some specific technical considerations for the selection of the supplier.
Structural Bonding Documentation
Request the supplier to provide the theoretical structural calculations and the pull-force test results to show how the ready-mix concrete is joined to the lattice girder reinforcement; a good manufacturer should have these readily available, and will not have to give a general assurance.
CAD/CAM Manufacturing Capability
Ensure that production is computer-controlled, a key factor in the precision so important in filigree that will enable it to handle custom architectural shapes without adding manufacturing error.
ISO Certification
ISO 9001:2015 is a minimum requirement for a well-managed quality system and should be looked for as a quality measure; it is especially pertinent because of the structural bonding responsibility that filigree systems have.
UAE Municipal Approval
Check if the supplier has UAE municipality approval for the product and if you are involved in multiple GCC country projects, find out how approval would apply to those projects as well – approval may be project-specific in other GCC countries.
Curing Method and Climate Adaptation
Enquire about the supplier’s reaction to conditions in the UAE by asking about the methods some are using to cure according to the season, such as steam curing in winter and water curing in summer – this is a truly climate conscious practice that is worth confirming and is generally of a seven to 10 day duration, depending on the consultant’s requirements.
Logistics: Delivery and Transport
Filigree slabs are normally stacked on a low-bed trailer, and double wall elements on specially designed low-bed trailers due to their geometry. Ensure the delivery arrangements from the supplier match your project location and schedule requirements, and resolve any border crossing costs if the supplier is located outside your home emirate.
Leading Precast Concrete Filigree Slabs UAE
1. KKK Precast Concrete Industry LLC
KKK Precast offers a variety of precast structural floor and slab systems which are suitable for residential, commercial and industrial projects throughout Dubai, Abu Dhabi and Sharjah, and are able to recommend the appropriate filigree or composite slab systems for project specific structural and architectural needs.
2. Emirates Filigran LLC (EMFIL)
Dedicated specialist in this class, EMFIL, is an ISO 9001:2015 certified manufacturer located in Ras Al Khaimah, manufacturing filigree slabs, double wall systems and stairs through CAD/CAM controlled precast plants. The company provides all across the UAE and project-by-project approval processes in the neighbouring GCC markets of Oman, Saudi Arabia, Qatar, and Bahrain under the approval of UAE municipal authorities.
3. Gulf Precast
Gulf Precast’s size and engineering depth is a relevant consideration when projects are considering composite or filigree-type flooring in addition to their proven hollow core portfolio, spanning 40 years of experience in the UAE.
4. Exeed Precast
Exeed Precast’s manufacturing facilities, such as the steel reinforcement advanced CAD/CAM technology, tailor-made mesh, auto-cutting and lattice girder technology steel manufacturing machinery, not only meet the needs of composite precast production, but also provide a foundation for producing filigree products.
The Precast Concrete Filigree Slabs UAE Design and Installation Process
The sequence is useful for making realistic plans for the project of the structural system using filigrees.
Design and Structural Coordination
The reinforcement required for the filigree element, and the specification and thickness required on site are checked against the project’s structural drawings and reinforced and bonded with the project’s structural consultant.
Manufacturing
Manufactured in CAD/CAM controlled factory environment, filigree elements are created with precise positioning of reinforcement and lattice girders, which project the desired specifications, and curing is managed according to the season.
Delivery
Slabs are usually transported horizontally on flatbed trailers and, where necessary, there are low bed trailers for double wall elements due to their geometry.
Placement
Precast filigree elements are craned in place and serve as permanent formwork that has exposed lattice reinforcement ready to bond with the next layer of concrete to be poured on site.
Site Concrete Pour and Curing
Precast base is then bonded to with ready-mix concrete, with the exposed reinforcement, forming a single composite assembly after curing.
UAE Approvals and Regulations for Precast Concrete Filigree Slabs UAE
As structural components of floors and walls, filigree slab systems must meet the structural code requirements of the relevant emirate authority (Dubai Municipality, Department of Municipalities and Transport, Abu Dhabi, Sharjah Municipality or equivalent in other emirates) when submitting the design of the project, including the structural bonding calculations between the filigree precast element and the site-poured concrete.
The supplier should have the current municipality approval and be able to provide the structural documentation required for project sign off and should have real experience in this category of products.
Conclusion of Precast Concrete Filigree Slab Suppliers in UAE
The market position of Filigree in the UAE precast market is truly unique – a combination of off-site production advantages of speed and site poured concrete advantages of design flexibility. Emirates Filigran LLC is the region’s specialist with true CAD/CAM manufacturing depth and multi-GCC project experience, and other structural manufacturers such as KKK Precast, Gulf Precast and Exeed Precast have precast/composite manufacturing experience that is relevant to projects considering this system.
As structural bonding responsibility is a key factor in the life of a filigree system, always ask for the supplier’s structural calculations and pull-force test data, check if the system is approved by the municipality and ask directly about curing techniques appropriate for UAE’s seasonal conditions before taking the project. When done properly, a filigree floor is a truly integrated structural component that when complete, no one can tell that it was originally two pours.