Made: Brick pavers

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Changes in Dutch Health and Safety Regulations have meant a great emphasis on automated processess – embodied here with the Tiger-Stone paver layer
Changes in Dutch Health and Safety Regulations have meant a great emphasis on automated processess – embodied here with the Tiger-Stone paver layer

What: Wienerberger Brick Pavers
Where: Kijfwaard West Factory, The Netherlands

If the boy who stuck his finger in the dyke and saved Holland from flooding was a company, it would probably be a brick firm. In fact, if it wasn’t actually turning a healthy profit, you could argue that a firm like Wienerberger was a model of selflessness – since most of its factories are likely to flood at some point. That’s because nine of the firm’s 15 Dutch plants lie outside the country’s protective dykes – here the geographical equivalent of being sent into exile – but there’s a particular reason for it. 

‘Holland is basically a delta and our proximity to the river is no coincidence,’ explains Patrick Jansen, export manager for Wienerberger. ‘We dredge the river for its clay, the raw material that forms our bricks. This keeps the river beds clear, controls their water levels and helps keep all our feet dry.’ But he adds that for perhaps a week a year, workers may have to boat over from the nearby Winterdyke; and ‘while we can still take orders and keep the kilns running, there are delays in getting the bricks out as the access road’s – well... underwater…’ 

The Kijfwaard West factory in summer, sitting alongside the Rhine
The Kijfwaard West factory in summer, sitting alongside the Rhine
The Kijfwaard West factory in winter, surround by the flooded Rhine
The Kijfwaard West factory in winter, surround by the flooded Rhine

And the firm has to pull out a lot of clay from the rivers, so it’s just as well that Wienerberger has a 50% share of the 600m-brick domestic market. At its Kijfwaard West plant, on the banks of the Rhine near the German border, the factory is dedicated to brick paver production, and part of Jansen’s job is to try and convince the market that traditional clay is the future. He explains that the 600m bricks amount to only 15% of the total domestic paver market, the other 85% going to concrete products. Jansen’s looking at incremental shifts. ‘A 3% rise in market share would have an enormous effect on our business,’ he explains, ‘and we’ve decided that it’s better to try and wrestle that share from the concrete industry than our brick competitors.’ Part of that strategy is to prove to the likes of you and me that aesthetics, performance and longevity win out in the long term over initial cost.

His argument is helped by the fact that Jansen’s a ‘brick head’, and loves the stuff. He came to the industry young and lights up when talking about the small paved squares of old Amsterdam. ‘They look good when they’re new, but when they are two or three hundred years old, with moss in the joints between the cobbles, they’re beautiful!’ he says excitedly. No wonder that, with UK sales manager Steven Hook, he is  the one charged with trying to increase the UK’s take up of Dutch pavers. Currently the firm exports about 15% of its production, a market with a turnover of around €20m. The UK was previously dominated with sharp, orthogonal extruded red clay pavers – the darling of 80s style private developments – but the country is moving towards a richer colour palette and the ‘rustic’ look provided by tumbled blocks. 

The Kijfwaard factory produces 20 different colours in four size formats, using standard firing techniques and ‘blue braising’. The latter involves running bricks through the kiln a second time, but in an oxygen starved environment. It produces interesting results. Red bricks go black or grey, while yellow turn green. ‘The process is permanent and the colour change homogeneous through the paver,’ says Hook. ‘But what’s amazing is that if you run them back through the kiln with standard oxygen levels, they revert to their original colours.’ Hook thinks the UK market, used to a limited palette (although the firm still produces Staffordshire blue pavers in the UK), is warming to the idea of a public realm made up of richer colours. 

‘A strong green paver has just been specified at London’s new King’s Cross Square as an accent colour,’ he notes, in the hope this trickle becomes a flood. And why shouldn’t it? The brick pavers outside Kijfwaard’s offices have been bathed in the Rhine’s waters often enough, and look all the better for the deluge…

1. Tiger-stone paver laying machine

Dutch health and safety legislation means that if more than 500m2 of paver area is laid, it must be done using a mechanical process. The Tiger-Stone paver layer, into which pavers are inserted, lays suburban streets just like a carpet. Hook knows it will be expensive getting this technology into the UK without legislation driving it. This  is a shame, as Jansen says the pavers pull up like a dream. ‘In Holland all our utilities run underground, but as there’s only sand between them; remove a few key blocks and the whole lot can be taken up and put back down just as easily,’ he says. 

2. Raw material

Wienerberger dredges 70% of the raw material for this plant from nearby rivers, with the rest mainly sourced from central and eastern Europe. Compounds are added to create colours, and lava stone additives to act as a plasticiser. These are added to huge hoppers ready for mixing and processing. Despite delays caused by war-time ordnance in the river, the factory processes nearly 1m tonnes of raw material a year. ‘We’ve already found three German grenades this week,’ says production manager Richard Klomp. ‘You have to stop the belts and call the police when that happens.’

3. Mixing/Homogenising

Made of different sized particles and additives, the mix first needs to be homogenised. ‘It has to be ground in stages so the mix becomes finer and finer,’ says Hook. This involves huge mechanical grinding wheels and mangles. At this stage water content will be about 15%, but getting it precisely right is critical. Once ground down, the moisture content of the mix is measured by checking its electrical resistance. If there is too little water, steam is pumped in under pressure to ensure perfect malleability for the moulds. Pavers go through the kiln at a higher temperature than wall bricks, to drive more moisture out and make them harder and stronger.

4. Forming the pavers

Mass moulds wait to receive the wet clay mixture. Before this they are sprayed with water and may be dusted with dry sand to ease removal. Water-struck bricks are not, which accounts for their slight ‘slump’ – the result of the drag of the clay in the mould. The Kijfwaard plant produces four different sizes of paver, the main size being the Slimpave, 200mm long by 50mm wide by 85mm deep. Replacing the mould template and cleaning the machine to change paver size can take nearly a day. After moulding, pavers are  checked for inconsistencies and either reprocessed or lined up in drying chambers to settle before being arranged on the kiln cars, ready for firing.

5. Firing

Cars take 96 hours to move from one end of the 200m long firing kiln to the other. Each car contains 10,000 pavers and the kiln can fit in 60 – enough material to pave 85 football pitches. As the pavers move through the kiln the temperature rises to reach about 1100°C about two thirds of the way in; this is done gradually to reduce the likelihood of bricks cracking as they fire. Those on the inside of the cars shrink slightly less than those on the outer faces, but as they are mixed on the pallets, this means no qualitative difference. This huge kiln will burn 60 tonnes of gas an hour at working temperature and is rarely turned off, even during floods.

6. Sorting and packing

Given that about 70% of the domestic paver market relies on automated laying, pavers must be sorted into their requisite laying patterns on the palette so they can be placed properly on site by the robotic ‘grab’ installed on the site plant machinery. This previously manual process has been completely automated. One robot picks bricks off the production line, while the next arranges them into the correct laying patterns – usually an ‘elbow’ diagonal arrangement. From the raw clay mix being loaded into the hopper to the pallets being sealed in plastic, the pavers will have spent around two and a half weeks in a factory set up to run for 16 hours a day.