Hollow Core Slab Installation Method Statement

[Zee Petty]

13 Directions will be given to drivers to reach the location of unloading, trailer is brought close to the building, under the crane area where erection of precast hollow core slabs is to be carried out.

2.4 Slabs will be delivered with open cores. Cores are to be closed with polystyrene core plugs either before lifting the hollow core slab from load or after erection but before grouting/screeding to avoid the flow of concrete in the core while screeding.

2.5 Suitable required to start erection of precast hollow core slabs works scaffolding will be provided with suitable safe access ladders, guard rail, handrail posts, and scaffold boards, scaffolding and platforms will be erected according to approved Methos Statement for Scaffolding ref. MRO-XXX-CIV-MST-00065.

2.8 Slabs are lifted directly from the trailer and placed in position by a mobile crane or tower crane. If the site is not ready then the slabs will be offloaded at the site on timbers safely in the designated storage area.

2.13 Full slabs are lifted using specially designed lifting equipment. Either a lifting clamp or lifting belts, depending on the site requirement/ access/ HCS Slabs size. The weight of the lifting equipment is as follows:

2.14 All the HCS of 150 mm to 320 mm thick will be erected using a lifting clamp or lifting belt. All the HCS of 400mm, 500 mm thick, and part slabs less than 1200 mm in width of all thickness will be lifted using a lifting belt.

2.16 The Hollow Core slabs are now ready to receive the reinforcement, MEP (if required), and the screed topping by the Main Contractor.

Topping concrete will be carried out as per MS ref. MRO-XXX-CIV-MST-00074.

The hollowcore production process begins with the drawing and design of a floor layout within a building. The usage of the building and loads applied will determine the depth, prestressed wire patterns and span of the slabs.

The design is accomplished using 3D CAD software. This can then be translated into a production plan for the hollowcore factory. Any additional details, such as the insertion of lifting pins, cut-outs and narrow units are included.

Production is accomplished by a team of factory operatives, and is often spread over multiple work shifts. Production planning is an important part of maximising efficiency and minimising waste of raw materials.

Hollowcore slabs are prestressed concrete elements. This means that they are reinforced by high strength, low relaxation steel wire or strand. The tendons are tensioned to a predetermined load prior to casting the slabs.

Due to the high forces involved, prestressing is a potentially dangerous operation, requiring strict health and safety procedures. It also requires specialist hydraulic equipment, either for single strand or multi-stressing.

Once the concrete has been batched to the requirements of the casting machine, it is delivered via a distribution system. Casting machines typically fall into 3 categories: extruders, slipformers and flowformers.

These can include: cleaning, oiling and wiring the beds, marking and detailing slabs, cutting slabs to required lengths, and equipment for lifting and stacking the finished product. Factories can range from labour intensive through to highly automated production.

The floor layout of hollowcore slabs in a building is designed using 3D CAD software. At this stage, design loads are used to calculate the depth and wire patterns of the slabs, depending on the spans required.

This is then translated into a production plan for the factory to maximise efficiency and minimise waste. Production plans include information such as cutting slabs to length, and detailing requirements such as insertion of liftings pins, notches and exposed cores.

The innovative Motus building system allows for constructing not only solid and sandwich walls but also three-dimensional hollow-core slabs in many shapes and designs. EGI, an Uzbek construction contractor, relies on the industrial prefabrication of these elements based on automated processes and the expertise provided by Vollert, the German equipment manufacturer.

The innovative Motus building system comes with a number of advantages, including affordable housing, new architectural highlights and high earthquake resistance. Its range includes not only solid and sandwich walls but also three-dimensional hollow-core slabs in many shapes and designs. EGI, an Uzbek construction contractor, relies on automated manufacturing processes and the expertise provided by Vollert, the German equipment manufacturer, for the industrial prefabrication of this building system.

Nowadays, urban architecture has to meet a large number of different needs, such as applying sustainable and resource-efficient construction methods while ensuring the quick completion of low-cost, affordable housing projects for the growing number of people living in mega-cities. Other important factors include quality of life, living comfort and attractive architectural features, as well as an effective response to the increasingly severe climate- and weather-induced changes and geophysical natural disasters. Currently, 1,300 earthquakes of magnitude 5 to 6 occur each year, causing severe damage and a death toll of 50,000 worldwide.

Kusmichev has been one of the driving forces behind preparing initial drawings and architectural designs in order to implement the new building system developed by the construction engineering team at Vollert, the German equipment manufacturer. He contributed his comprehensive hands-on expertise as well as a huge amount of data and statistics stemming from his previous career in the former USSR.

Vollert developed an innovative production process in order to respond to all these practical needs. Instead of employing an extrusion or slipforming method, the new hollow-core slabs are produced on a pallet circulation system. Each prestressed concrete hollow-core slab is manufactured exactly to the specified shape and dimensions in a waste-free process, rather than cutting the continuous floor slab to the required size after concrete pouring. The production line includes a newly designed machine with cylinders to create the hollow cores. These cylinders are inserted into the slab form only temporarily during concrete pouring. The number and shape of the voids can be varied very flexibly, which would not be possible in an extrusion process on long casting beds. In addition, the new process makes it possible to insert cable conduits, utility ducts for water supply and ventilation, and custom embedded parts, thus opening up completely new options for structural or technical designers. A single-strand prestressing unit ensures the application of the specified tensioning forces. For this purpose, the production pallets were designed such that the maximum possible prestressing forces can be transferred to the precast element.

The mesh welding unit and the lattice girder production line supplied by the Austrian manufacturer EVG are also fully automated. They utilize state-of-the-art robotics and are fully integrated into the control system.

The reinforcement production line was installed centrally as the core piece between the hollow-core slab and solid wall production lines. A sophisticated Vario Safe safety concept ensures that hazards are kept to a minimum.

An EVO e120 extrusion unit supplied by Nordimpianti was installed for additionally producing standardized hollow-core slabs for industrial construction. This extruder is designed for the manufacture of up to 1.2 m wide and 22 cm thick floor slabs. Depending on the specific project and order, up to six voids can be produced using the existing form insert. In addition, volumetric and structural precast elements are produced on custom-designed stationary mold systems. For this purpose, several high-performance tilt tables for extensive custom elements, a hydraulic duplex column mold and a duplex beam mold were installed. The production line also includes a duplex Variostep stair mold from the Vollert custom mold range to allow for a particularly flexible design and the production of right and left-turn staircases with up to 20 steps in an upright position. A modular side wall allows for the production of 900 to 1,500 mm wide stairs with steps in a continuous range from 220 to 320 mm and a pitch between 150 and 200 mm. Stairs are produced on the framing side, which ensures architectural concrete quality on three sides. In addition, a landing platform can be easily installed at any step of the stair thanks to the rear steel panel that can be moved horizontally and adjusted in its height. Besides staircases, a custom block mold makes it possible to also produce ventilation shafts for the new construction projects.

A Liebherr concrete mixing unit was installed as the central source for supplying structural and ready-mixed concrete to all in-house concreting processes and external sites. The integrated ring-pan mixer allows for an output of 2.25 m of concrete per batch.

Hollow-core slabs weigh up to approx. 40% less than solid floor slabs, thus requiring less concrete in manufacturing. Therefore, they are widely used all over the world. However, the slab widths are...

The beams are marked with identification codes in accordance with the drawings. Beams can be stored in piles, but remember to verify the bearing capacity and the level of the surface. As DELTABEAM composite beams' visible bottom flange is painted with anticorrosive primer, piling strips must be used under the beams to protect the surface treatment. Piling strips should be free from grease or other substances that may damage the surface treatment. For long-term storage, the beams must be covered.

DELTABEAM can be lifted and moved using ordinary lifting equipment, such as cranes or forklifts. The weight of each DELTABEAM is displayed on the product sticker on the beam or in the fabrication drawings. Within the EU, all beams have the CE marking sticker.

In special cases, when there are no lifting holes, DELTABEAM can be lifted with chains attached to the web holes. Sometimes a third chain is needed in order to maintain balance. For example, DELTABEAM with wide inbuilt formwork should be lifted using the lifting holes and a third chain should be assembled to the formwork.

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