Singapore relies on precast concrete elements

Highly automated factories producing precast concrete elements have been initiated by the state to increase usage of precast concrete in Singapore construction industry. The slogan: out with time-consuming and labour-intensive traditional construction methods, in with maximum pre-fabrication. Straits Construction Group, one of the largest construction companies in Singapore recently commissioned such a plant. It produces not just wall and floor panels, but also pre-stressed solid slabs and 3D kitchen and bathroom modules – in one factory but on five levels. The associated plant and software solutions have been developed by companies in the Progress Group. The subsidiary company, Ebawe Anlagentechnik assumed the principal responsibility for the overall concept and installation.

For some years now, Singapore has been promoting industrialization and automation of its construction industry by means of numerous guidelines and incentives. The city state‘s objective is to optimize land use, to improve productivity and quality and to create new, more highly skilled jobs.

In this context, precast concrete element technology takes on a particular significance. This is why the state building authority, the Building and Construction Authority (BCA) is encouraging construction companies to invest in this forward-looking technology. By means of tendering processes it is making land available for highly automated production plant and is inviting tenders for projects, which are then realized by private firms. These factories, known as ICPH (Integrated Construction and Prefabrication Hub), are intended to play a part in creating new buildings space in a fast, cost-efficient manner and thus to rejuvenate the building infrastructure in the coming years and decades.

Integrated Construction and Prefabrication Hub

At the beginning of October last year, the inauguration of the second ICPH was celebrated. Constructed by Straits Construction Group, one of the largest construction companies in Singapore, in close cooperation with companies in the Progress Group, the highly automated plant on five levels ensures the company‘s in-house supplies in prefabricated concrete walls and ceilings and entire room modules

At the opening ceremony, which was held in the new works in the presence of the Minister for Finance, Heng Swee Keat, the Ambassador of the Federal Republic of Germany in Singapore, Ulrich A. Sante and the entire top management team from Straits Construction Group, it was generally felt that this technology has a secure future. In his speech, the Singaporean Finance Minister stressed the importance of such highly automated plants. „ICPHs are significant developments, housing exciting innovations and technologies that can raise productivity and bring new energy to the building industry.“ Heng Swee Keat‘s opinion is based on four crucial points: firstly, ICPHs will optimise land usage, since several construction processes would be amalgamated in one place; secondly, such plants increase labor productivity, since less time and a smaller workforce are required to produce precast concrete elements; thirdly, the controlled production conditions make a significant contribution to improving the quality of prefabricated elements; and finally, new, more highly skilled jobs would be created, which would meet the increasing demands of the population.

Production on five levels

In September 2014, after Straits Construction Group was awarded the tender for the 20,000 m² of building land in Kaki Bukit, the work for the new ICPH began. The new build comprises a factory building with ground flour and four storeys and a twelve-floor dormitory block. In conjunction, Straits Construction Group has founded its own subsidiary company Greyform Pte Ltd, to operate the works.

The factory building with its attached high-bay warehouse for floor and wall panels is unique in concept and form. On the ground floor the carrousel plant has been installed by Ebawe Anlagentechnik and lines for the production of pre-stressed elements have been installed by Echo Precast Engineering. The first floor houses the entire system from Progress Maschinen & Automation for the manufacture of made to measure mesh, while on the second floor the Tecnocom shuttering molds for stationary manufacture have been housed. Bathroom and kitchen modules are finished on the third floor; these are then stored on the fourth and last floor.

Ground floor: highly automated carrousel plant

The highly automated carrousel plant occupies the greater part of the ground floor of the factory. Ryan Lim, Greyform‘s Assistant General Manager stated, “This plant is the first in Singapore to use automated robot technology. With its flexible design it not only ensures the highest efficiency, but also guarantees that delivery times are rigorously adhered to – even where the elements are totally different.”

A total of 48 pallets circulate on the circuit. At the start of every production cycle these are loaded with the appropriate shutters by the Form Master shuttering and deshuttering robot. Once the made to measure mesh has been inserted, the fresh concrete is accurately spread by an automatic concrete spreader and compacted. A levelling and vibrating beam ensures that the elements‘ surface quality is optimal. Finally, a pallet stacker places the precast concrete elements in one of a total of 38 shelf compartments for curing. When the finished wall and floor panels have been removed and transported to the high-bay warehouse, the shutters are removed, cleaned and automatically replaced in storage by the deshuttering robot. Once the pallets have been cleaned, the cycle begins afresh.

Innovative high-bay warehouse

Even the fresh concrete is delivered automatically to the carrousel plant. A bucket conveyor transports the material directly to the concrete spreader from a ground-batching plant, supplied by Wiggert & Co. GmbH. A second bucket conveyor system ensures that slipformer production is supplied with drier concrete.

The plant‘s special feature is the high-bay warehouse. Because of the scarcity of space in Singapore, the warehouse has not been planned horizontally, as is usual, but vertically. It is fully automatic and in three towers on seven different levels it offers space for a total of 5,800t of sold walls and floors, pre-stressed elements and hollow core slabs. In addition, entire racks, rather than individual concrete elements are stored and retrieved. This massively reduces standby time for the HGVs and therefore delivery time.

This degree of automation has a major impact on the productivity of the plant. “Within ten days a workforce of 60 persons is able to produce precast concrete elements for 48 four-room dwellings. On traditional construction sites three to four times the number of employees and twice as much time would be required,” said Assistant General Manager Lim with satisfaction.

Slipformer for pre-stressed elements

Greyform uses the S-Liner T40 slipformer from Echo Precast Engineering for the production of pre-stressed precast concrete elements. By means of three different slipformer molds not only is it possible to produce hollow core slabs 7 to 40 cm in height and 120 cm or 240 cm in width on the 84 cm long production lines; pre-stressed solid slabs 7 to 20 cm in height and 100 cm or 210 cm in width can also be produced. Additional equipment, such as two different saws, a multi-functional trolley and the associated lifting equipment complete the plant. “The hollow core slabs allow us to cover longer span with single elements – in addition, it is possible to work on the construction site with less columns,” explains Ryan Lim.

The steel mesh for all the production lines is produced on the first floor. “Here we have installed four different systems from Progress Maschinen & Automation, with which we are able to manufacture all the products required,” says Lim with satisfaction. “This set-up allows us to react with a high degree of flexibility and to produce more than 100t bespoke mesh, cages, bars and stirrups per day.”

An M-System Evolution mesh welding plant is used here for the manufacture of bespoke mesh in various molds and with bending run-off. The machine has been developed for flexibility in use and therefore blends in perfectly with Greyform‘s production concept. When the mesh has been produced, a crane automatically stores it in a buffer, from where the pallet circuit is supplied. Cage production is delivered and pre-stressed ceilings are manufactured by manual processes.

Bars, bars with bending run-off, stirrups and 3D stirrups are manufactured by the second system, an EBA S16 Plus 3D automatic stirrup bender. Fast, automatic wire change and fully automatic setting of the straightening rate ensure that production is fast and continuous. In addition, a Shear Line bending machine for individual rebar and a cage welding machine have been installed.

Reduced costs thanks to modules

The second floor has been reserved for stationary production. In addition to the three staircase shutters and in cooperation with the Northern Italian prefabricated bathroom specialists, Bathsystem S.p.A four 3D shuttering molds and the associated four production tables for the manufacture of bathrooms and kitchens have been delivered to Greyform. The 2.8 m high shuttering molds are remarkably flexible, since both the wall shuttering and the floor slab are adjustable. This means that 3D elements can be produced in a variety of dimensions. Each module is manufactured in two sections, then placed together on one of the production tables, and provided with a floor.

Because the pre-fabricated bathrooms and kitchens are up to 90% pre-fabricated, it is possible to reduce costs significantly. Sanitary equipment, electricity systems and furnishings are installed as part of the production process at Greyform. Thereafter the elements are loaded onto HGVs and delivered just in time to the construction site, where a crane places them in their final position. The company is thus able to comply with the 65% quota for pre-fabricated bathroom modules imposed by the BCA.

Industry-specific MES and ERP systems

The software plays a large part in ensuring that the production processes run smoothly. The ebos and ProFit MES systems, developed by Progress Software Development, consistently accompany all the aspects of the production process in the pallet circuit and manufacture of made to measure mesh. These integral systems thus replace a multitude of partial software solutions. This avoids interface problems and the employees can perform their entire work process in one homogeneous, user-friendly system. erpbos, a solution developed specifically for the precast concrete industry, has been installed as the superordinate ERP system. It serves the planning and control of all business and production processes - starting from sales, calculation, project management through production and installation planning to logistics, materials management, controlling and Human Resources. The Assistant General Manager, Ryan Lim declares himself satisfied with the Progress Group’s complete software package. “All these systems ensure a seamless flow of data, which increases not only our productivity, but also the quality and precision of our products.”