Concrete curing system as a core component in a state of the art

CPI – Concrete Plant International – 3 | 2016 www.cpi-worldwide.com74

CONCRETE PRODUCTS & CAST STONE

Michael von Ahlen, CPI worldwide, Germany

The new highly automated concrete blockmaking machine is attached to one of thethree existing ready-mixed concrete pro-duction sites, resulting in effective produc-tion in both product divisions. The compa-ny’s delivery radius is 60 km for ready-mixed concrete and 80 km for the concreteblocks. Currently, the ready-mix concretesites together produce approximately60,000 m³ concrete per year. The produc-tion of concrete products in two shift opera-tion amounts to approximately 1 million m²per year.

About half of the hall area is occupied bythe new concrete block making machine,which would allow for extension by a fur-ther production plant. All plants currently inoperation are BSI-certified to ensure maxi-mum product conformity.

Laird Brothers consciously chose tworenowned suppliers to the concrete prod-ucts industry in Rekers and Rotho in order tobe able to manufacture concrete productsin the usual way with high quality parame-ters.

In addition to the KRS 4 concrete blockmaking machine, Rekers Maschinen- undAnlagenbau from Emsland also deliveredthe handling and transport systems on thewet and dry sides. The fully automatic con-crete curing system from Rotho ensures opti-mum curing and post-treatment of the con-crete products. The refinement of pavingstones, for example, is also possible bymeans of a stationary ageing unit fromKBH.

The concrete production is supplied withhigh-quality aggregates from the compa-ny’s four own quarries situated nearby. A

heating system can preheat aggregates forthe ideal preparation of ready-mix concretein particular, in order to be able deliverquality concretes even in cold seasons. Theaggregates for the production of the con-crete goods can be preheated separately,ensuring independent operation.

Concrete curing system as a core component in a state of the art concrete block production facility

Laird Brothers, Forfar, Angus DD8 3NQ, United Kingdom

The family-run company Laird Brothers from Forfar in Scotland has 50 employees and is known in large parts of the country as a reliablesupplier of concrete. The company is now well prepared for the future with the construction of a new 4,000 m² production hall at the mainplant in Forfar and the acquisition of a new concrete block making machine at the beginning of this year. This investment focuses in partic-ular on the production of high-quality concrete blocks, because the demand for such products has strongly increased in recent years. Withthe extension of the product portfolio by concrete paving blocks, masonry blocks and split blocks, the cousins Jamie and John, together withboth their fathers Jim and Alex, now want to expand further, because as a self-sufficient enterprise the company can draw on almost 70years of experience with four quarries of its own, three ready-mixed concrete plants, mobile mixing plants for smaller projects, its own fleetof vehicles and an already existing Finlay egg laying concrete block making machine. The first production runs with the new plant began afew weeks ago, marking not only a milestone for the Laird Brothers company, but also a premiere for Rotho of Germany, who supplied theconcrete curing system. The newly developed Rotho-ProCure concrete curing system represents the state of the art and has been imple-mented here for the first time in a concrete block production line. The climatic conditions prevailing at this site made the use of this advancedcuring and post-treatment system necessary, because widely varying ambient temperatures in combination with constantly changing humid-ity levels in the area mean that homogenisation of the curing process of concrete products is barely possible without sacrificing quality.

The new production hall at Laird Brothers with a 7-hectare storage yard.

A Haarup mixer and an Eirich mixer supplythe concrete block making machine withcore and facing concrete.

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Two concrete mixers provide the high-performance concrete blockmaking machine with fresh concrete. A Haarup mixer with a mixingvolume of 3 m³ produces the core concrete, while an Eirich mixerproduces the facing concrete. Coloured concretes are also pro-duced at Laird Brothers.

After mixing, two conveyor belts transport of the core and facingconcrete to the block making machine, which is fully enclosed fornoise protection. The machine consists of a massive machine frame

The concrete block making machine type KRS 4 from Rekers ...

... the concrete block moulds are from Rampf.




made of MSH profiles and is equipped withmany high-quality components, such as amobile facemix with hydraulic locking,motorised height adjustment for feed boxand bunker, self-supporting feed box withservo drive, colour-mix drawing sheet forcore and facing concrete, pneumatic fastclamping for mould and tamper, plus theRekers Vario servo vibration and a board-friendly walking beam conveyor.

In addition, the block making machine hasa comprehensive safety system that protectsthe operators against occupational acci-dents. The acoustic enclosure has twoentrances to the machine, which greatlysimplify cleaning and maintenance. Dustaccumulating in the enclosure is filtered outby an external dust extraction system.

The production boards with the fresh con-crete products are removed by a conveyorbelt from the acoustic enclosure and passthrough a random quality control. The con-veyor belt takes the production boardsonwards through a small opening in thelarge climatic chamber and places themdirectly into the elevator.

Rotho-ProCure concrete curing systemas a core component of high-qualityconcrete block production

The intake of the products through the smallopening in the curing chamber ensuresmaximum energy efficiency, i.e. low lossesof heat and moisture. At any time and with-out leaving his workplace, the operator caneasily see the current occupation and statusof a total of 16 passages of the concretecuring system, each of which has 22 floors.A maximum of 6,688 production boardscan be stored at the same time.

Once the elevator is completely filled, thefinger car takes the batch from the elevatorand transports the fresh concrete productsinto the designated chamber of the racksystem. The transport speed of the fingercar is 1 m/s. As soon as the finger car hasreached the appropriate position in front ofthe rack chamber, it rotates by 90° anddrives into the chamber to store the con-crete products.

The curing chamber was implemented as alarge climatic chamber in which the eleva-

tor/lowerator and transfer table were inte-grated. The Rotho-ProCure system consistsprimarily of a steam generator with watersoftener, a hot-air generator and an airrecirculation system. The highly effective airrecirculation system installed at the rear ofthe rack system, which has multiple circula-tion circuits, extracts the air above the cur-ing rack and blows it in again via a pipingsystem underneath the first level in order toprotect the concrete products. The samerequired quantity of air thus flows aroundeach product. The intelligent system con-

Boards from Wasa provide sufficient stability and load-bearingcapacity for the transport of the concrete products.

Random quality control before storage in the curing chamber.

The production boards with the fresh concrete goods are transported into the elevator in the curing chamber by a conveyor belt.

The elevator on the right in the picture isfilled with fresh products.


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troller continually measures and regulates the temperature and rel-ative humidity in the curing chamber and adjusts them if necessary.An effective exhaust air system limits the maximum moisture contentin the curing chamber.

The modularly constructed ProCure system has been deliberatelyinstalled separate from the air recirculation system so that existingair recirculation systems can also be retrofitted with heating andhumidification. The separately operating circulation circuits allowthe input of large amounts of air in a short time. This method ensuresa reliable and very high homogeneity of temperature and humidityinside the large chamber.

Unlike a system with central fan, any fan failures here will causeonly small restrictions in the operation. In addition, the axial fansinstalled in the piping system are designed to allow the transport ofsignificantly higher amounts of air than with a central fan.

The advantages that this complex concrete curing system brings are,apart from the fast formation of the early strength of the concreteproducts, the associated potential saving of cement and an opti-mised homogeneity with regard to the appearance of the concreteproducts. Furthermore – and this is always an issue where high-qual-ity concrete products are concerned – the occurrence of primaryand secondary efflorescence is reduced due to the ideal curing con-ditions.

Control station of the new concrete block making machine, from which all important parameters can be controlled, for example the storage management of the curing chamber.




A total of 6,688 production boards can bestored at the same time in the large climaticchamber.

Air outlet at the bottom of the chamber. An efficient circulation system ensures a uniform flow with the precisely tempered air mixture.

Circulation circuits of the Rotho-ProCure system

The finger car takes the cured products outof the rack chamber.

Transfer of the products to the lowerator.

The platform of the finger car rotates by180° during the journey.

ProCure heating and steam system

Conclusions

The management at Laird Brothers optedfor first-class equipment for their new pro-duction plant among other things due to thehigh demands that the company places onits concrete products. It follows that high-quality products can only be manufacturedwith high-quality production equipment andtechnologies. Although no reference systemof the ProCure concrete curing system wasavailable at the time of the planning of theplant, Rotho was able through intensiveconsultations and a tour of the manufactur-




ing facility at the headquarters in Neun -kirchen, Germany, to convince its businesspartner Laird to go ahead with the invest-ment. Finally, a professional and individual-ly tailored consultation provided the decisive argument for the purchase of thisprototype. �

Laird BrothersOld Brechin Rd. Forfar, Angus DD8 3NQ, United KingdomT +44 1307 466577F +44 1307 468642www.lairdbros.co.uk

Robert Thomas Metall- und Elektrowerke GmbH & Co. KG Hellerstr. 657290 Neunkirchen, GermanyT +49 2735 7880F +49 2735 [email protected]

Rekers GmbHMaschinen- und Anlagenbau Gerhard-Rekers-Str.148480 Spelle, GermanyT +49 5977 9360F +49 5977 936250 [email protected] www.rekers.de

Wasa AGEuropaplatz 4 64293 Darmstadt, GermanyT +49 6151 7808500F +49 6151 7808549 [email protected] www.wasa-technologies.com

Rampf Formen GmbHAltheimer Straße 189604 Allmendingen, Germany T +49 7391 5050F +49 7391 505142 [email protected] www.rampf.com

KBH Baustoffwerke Gebhart & Söhne GmbH & Co. KG Einöde 287760 Lachen, GermanyT +49 8331 950347F +49 8331 [email protected] www.k-b-h.de

FURTHER INFORMATION

Rekers also supplied the transport and handling equipment on the dry side of the new plant.

Removal of the block pallets to the 7-hectare open-air storage yard.

View the video of Laird’s new concrete block pro-duction facility at their site in Forfar, Scotland:

Simply scan the QR code with your Smartphoneand watch the video!


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Concrete curing system as a core component in a state of the art