christian prilhofer consulting, 83395 freilassing, …...peter kawan, christian prilhofer...

Peter Kawan, Christian Prilhofer Consulting,Austria

Alcrete Ltd. in Ireland, a pre-cast factorywhich can produce pre-cast elements forup to 5,000 housing units per annum,started producing pre-cast housing com-ponents this year. With the new factorythey reduce build up time by up to a thirdcompared to certain types of concretehousing construction and are able to pro-vide quality homes at affordable prices.

Many houses in Ireland are covered by aexternal cavity wall and therefore the pro-duction plant had to include the opportu-nity to produce solid walls with cavity.

The cavity wall elements consisting of theload-bearing concrete part of the wall, thevapour control, the insulation, the cavityand the carrier with bricks or mortar can

be produced in the new pre-cast plant,too. But before the design of the plantstarted some queries about the buildingsystem like special solutions for coveringthe corners, joints between the solid wallsand connections between the windowframes and the carrier had to be solved.

The new pre-cast plant is based on a 13-acre site in Arthurstown, Kill Co Kildarenot too far from Dublin and the factoryunit covers nearly five acres.

The project started with a ground surveyand because of the bad soil conditionspiling was essential.

The improvement of the soil conditions ledto additional expenditure.

To meet the requirements of the variety oflandscapes in Ireland, the facilities had tobe painted in green colour and the total

Production of double walls and solidwalls with cavity at Alcrete Ltd., Ireland

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PRECAST CONCRETE ELEMENTS

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Christian Prilhofer Consulting, 83395 Freilassing, Germany

Within the last decade Ireland’s economy wasbooming and the infrastructure can’t keep up.Due to this circumstance Irish building companies

were looking for building systems with solutionssuch as fast-track building and lightweight build-ing.

CPI – Concrete Plant International – # 1 – February 2006 www.cpi-worldwide.com

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Factory building with three wings and batching plant

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Soil composition of the building site

05-Fertig_190-209_eng 13.02.2006 10:25 Uhr Seite 200

height of the building (including the batch-ing plant) must not be higher than 14 m.

The production building which can beexpanded in the future for example with aproduction line for hollow core slabs orstructural elements is made of steel andequipped with several mezzanines for theproduction of floor slabs, solid walls anddouble walls. Two of the three wings in-clude the pallet circuit itself and the thirdwing includes the reinforcement prepara-tion and moulds for the production ofbeams and columns.

One of the first parts of pre-cast plant tobe assembled was the batching plantbecause it was used for the manufacturingof the floor plate. The batching plant withone mixer is designed to provide the pro-duction plant with max. 30 m3 readymixed concrete per hour and can beexpanded with a second mixer for anadditional production line in the future.

A bucket conveyor is used to transport thefresh concrete from the batching plant tothe concrete spreader. This transportsystem has its own control system and isworking automatically by means of acommunication between the batchingplant and the concrete spreader.

The pallet circuit itself is designed to pro-duce the following products:

• Solid walls made of normal concrete(with or without cavity)

• Filigree slabs

• Double walls

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www.cpi-worldwide.com CPI – Concrete Plant International – # 1 – February 2006

Peter Kawan (1963), mechanicalengineer, worked from 1985 to1997 at Filzmoser MaschinenbauGmbH where he was in charge ofthe design and sales managementof machines and systems for theconcretereinforcing-steels

processing industry. He joined Christian Prilhofer in 1997 as projects manager and has been responsible forthe Wels/Austria office since 1999.

[email protected]

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Piles in the area of the curing chamber

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Piling equpiment 6

Batching plant without cladding

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Assembly of the production building


Due to limited knowledge about the newbuilding system in Ireland and due to theproduct mix, the production plant has tobe as flexible as possible. After a check ofthe opportunities to use a second handplant from Eastern Germany which wasrejected because of high adaptation

costs, a new flexible pre-cast plant wasdesigned by Christian Prilhofer Con-sulting. The plant concept is done in sucha way to guarantee the highest possibleoutput and the maximum efficiency oflabour and machines which is done insuch a way that the unproductive time ofmachines and workers is cut down to aminimum. Producing different products atthe same time is possible without disturb-ance in workflow and efficiency.

This system in the final stage of extensioncan produce 150 m2 of floor slabs or 75 m2 of double walls or 80 m2 of solidwalls (finished products). The whole pro-cess is controlled and supervised by themaster computer which receives the datadirect from the CAD system with all theinformation that are required for produc-ing the concrete elements.

The maximum number of pallets in thecuring chamber is 80 pieces and the de-scription of the production process of thepallet circuit is as follows:

Demoulding area

The demoulding area is created is such away that a parallel demoulding of walland floor elements is possible. That meanstwo cranes are able to work at the sametime without disturbing each other. In case

of solid wall production the shutters haveto be removed from the pallet first andbecause of this the finished pallets with

solid wall elements are taken out of thecuring chamber with the help of the rackoperator and are transported to a posi-tion where a demoulding crane for thehandling of solid wall shutters is installed.With the help of this demoulding crane allshutters are removed on placed onto aconveyor belt. The shutters are transpor-ted to a cleaning and oiling device espe-cially for solid wall shutters with integratedmagnets. Afterwards the shutters are trans-ported to the shuttering robot. After allshutters have been removed from the pal-let the pallet is transported to the tiltingtable where the pallet is tilted for about85° and the wall-elements can be liftedfrom the pallet with the help of two paral-lel-working overhead cranes. The ele-ments are put into transport racks for wallswhich can be placed on seven depositpositions. After lifting off the wall elementsthe pallet is tilted back and transported tothe pallet cleaning station. The demould-ing of the double walls is similar to thedemoulding of the solid walls but the pre-cast elements are removed from the palletbefore the shuttering system. Filigree slabscan be lifted off the pallet with a speciallifting device for floor slabs or by meansof the overhead crane and then the slabsare laid to stacks according to thepreviously determined stacking order.After pre-cleaning all pallets from the pal-let circuit come together to a reunion-pointof the different circles in the plant wherethey are cleaned and oiled. �


202 CPI – Concrete Plant International – # 1 – February 2006 www.cpi-worldwide.com

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Preparation of the floor plate

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Demoulding area in the construction stage


Handling of shutters andformwork

Cleaned and oiled pallets are ready for anew production circle and are broughtinto the area of the shuttering robot withthe help of the cross lifting truck, lifted upand fixed in a steel structure for the furtherprocessing. Additionally the shutters withthe integrated magnets are transportedafter cleaning and oiling by means of con-veyor belts in the area of the shutteringrobot.

In the first construction stage one robotsystem is responsible for the storing andplacing of the shutters but the pallet circuitis designed in a manner to be extendedwith a second robot system.

The shutters are placed onto the palletwith the shuttering robot according to theCAD-Data in automatic mode and afterthat the pallet is transported to the nextfree station for manual completion of theformwork. The shutters which were set bythe shuttering robot are then completed,for example with pull-on profiles, telesco-pic profiles, formwork for doors and win-dows and inserts like sockets.

Furthermore the manual completion offormwork is disconnected from the palletcircuit which separates this level from thetransportation area. When completion of

formwork is done, safety railings are liftedup and the pallet is transported to the nextfree station in automatic mode.

Automatic ReinforcementCentre

After completion of formwork the pallet istransported to one of the reinforcementstations where bars and lattice girders orwelded meshes are laid onto the pallet. In

the first construction stage Alcrete Ltd.uses a reinforcement centre with a robotsystem for bars and lattice girders. This reinforcement centre consists of astraightening and cutting machine, a lat-tice girder cutting line and a robot systemwhich places the transversal, longitudinalbars and lattice girders according to theCAD data on the pallet of a pallet circuit.The robot system is equipped with twoarms or heads which can place up tothree bars or girders at one go. One ofthe robot arms can be rotated by 90° toplace the transversal bars or the girdersfor the double wall production on the pallet.

An interference of the pallet movementand the movement of the robot axis redu-ces the cycle time. Another advantage isthe use of two production lines becausethe time for changing the pallet will beneutral for the production process and therobot is able to work on one of the palletswhile the pallet on the other line will bechanged.

The pre-cast plant is designed in a waythat a mesh welding plant can be retrofit-ted. In this special case meshes are wel-ded automatically according to the CAD-Data and the mesh welding plant is produc-ing exactly every mesh for every singleelement.

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Shuttering robot

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Mezzanine for manual shuttering


Casting and compactingarea

After reinforcement is finished the pallet istransported into the area of the concretespreader where the process of placing theconcrete and compacting it is divided intwo independent processes to save time.Casting can be done manually for solidwalls and in automatic mode for slabsand for double walls. The supply of con-crete is done with an automatic concreteconveyor travelling between the batchingplant and the concrete spreader.

After casting the compaction processstarts by shaking or vibrating dependingon the thickness of the elements and of theconcrete consistency. The casted palletswith elements like filigree slabs, solid wallsand the first shell of the double wall aretransported to the curing chamber andthe second shell of the double wall istransported for further processing to thedouble wall equipment.

Production of double wallsand solid walls with cavity

For the production of double walls a vacu-um turning frame is used. The pallet withthe first shell of the double wall which wasconcreted one shift before and which hasfinished its hardening process is broughtto a position where the elements are liftedoff with a special device and placed ontothe turning frame. The positioning of theelements is checked and afterwards thevacuum is activated. The turning frame islifted and is turning 180° in automaticmode. When the frame has turned thefreshly spread second shell is brought inunderneath and then the frame with theelements of the first side is let down, untilthe lattice girders, fixed in the first shell,sink into the fresh concrete of the secondshell. Then the second shell is compactedby shaking the pallet. The next step is todeactivate the vacuum, to lift the frameand then to transport the pallet with thedouble-walls into the curing chamber.When the frame has turned back 180°and is let down again the production ofthe next double walls can start.

Solid Walls can be smoothened with ahelicopter system and after the pre-harden-ing time the pallet with the solid wall ele-ments is taken out of the curing chamberand brought to the mezzanine with thehelicopter-smoothening machine.

The solid walls with the cavity are alsoproduced on this mezzanine and in thiscase the pallet with the hardened solidwalls is brought by means of the rack ope-rator from the curing chamber to the mez-zanine floor. On this mezzanine floor asmall pallet circuit for the completion ofthe solid walls is located. The cavity con-sists of an insulation, the air cavity and acement board with brick slip or mortar.The parts for the cavity wall productionwill be stored and prepared on the mez-zanine. After finishing the cavity walls thepallet will be brought by the rack opera-tor to the curing chamber.

Curing chamber

The curing chamber is a rack system inwhich the pallets are brought in like a draw--er by the rack operator and the segmen-ted doors are opened by the rack opera-tor when pallets are taken out or brought



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Reinforcement centre

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Casting and compacting area


in. The whole curing chamber is cladded with insulating panelsand heated with a directly heated hot air generator.

With this flexible pallet circuit Alcrete limited is well prepared tomeet all the requirements of the market in Ireland in the future.

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Rack with solid walls

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Curing chamber and rack operator during the assembly

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Batching plant with cladding

Further information:

Alcrete Ltd.Arthurstown, Kill, Co Kildare, IRELANDT +353 45 878260F +353 45 [email protected]

Christian Prilhofer ConsultingPommernstraße 1783395 Freilassing, GERMANYT +49 8654 69080F +49 8654 [email protected]

ABUS Kransysteme GmbH Sonnenweg 1 51647 Gummersbach, GERMANYT +49 2261 370, F +49 2261 [email protected]

Bibko Umwelttechnik & Beratung GmbHSteinbeisstraße 1+271717 Beilstein, GERMANYT +49 7062 92640F +49 7062 [email protected], www.bibko.com

Filzmoser Maschinenbau Ges. mbH Unterhart 764641 Steinhaus b. Wels, AUSTRIAT +43 7242 34340 F +43 7242 343430 [email protected] www.filzmoser.com

Kraft Energy Systems GmbH & Co. KG Stühlenfeld 42 49699 Lindern, GERMANYT +49 5957 96120 F +49 5957 961210 [email protected] www.kraftenergy.com

Nemetschek Engineering GmbHStadionstraße 15071 Wals-Siezenheim, AUSTRIAT +43 662 8541110F +43 662 [email protected]

Unitechnik Cieplik & Poppek AGFritz-Kotz-Str. 1451764 Wiehl, GERMANYT +49 2261 9870F +49 2261 987510 [email protected]

Vollert GmbH & Co. KG Stadtseestraße 12 74189 Weinsberg, GERMANYT +49 7134 520 F +49 7134 52202 [email protected] www.vollert.de

Weckenmann Anlagentechnik GmbH &Co. KG Birkenstr. 1 72358 Dormettingen, GERMANYT +49 7427 94930, F +49 7427 949329 [email protected] www.weckenmann.de

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christian prilhofer consulting, 83395 freilassing, …...peter kawan, christian prilhofer...

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