Wim Kramer, Technical Advisor at the Dutch ‘Betonhuis’ (Concrete House) and Chairman of EUPAVE’s working group on Best Practices, has retired since the 1st of June 2020. Wim has been active for almost 35 years in the Dutch cement association and 13 years in EUPAVE. In the article below, Wim gives his viewpoint on the use of concrete in transport infrastructure in the Netherlands. After highlighting a wide range of applications, he appeals for a long term approach, in which concrete pavements are fully appreciated.
We take this opportunity to thank Wim for his great support all these years and wish him a good retirement! We also welcome Mr. Jeroen de Vrieze, who will take over Mr. Kramer’s commitments within the Dutch “Betonhuis” and EUPAVE.
The viewpoint of Wim Kramer from the Dutch Cement & Concrete Centre on concrete transport infrastructure in the Netherlands.
Original article by F. de Groot, published on gwwtotaal.nl on 11 December 2019
Concrete is the most widely used material for the construction of civil engineering structures and waterworks. But concrete is also suitable for many other applications in infrastructure, such as road pavements – although the Netherlands traditionally builds roads with asphalt. Does this mean that there are hardly any possibilities for concrete paving in the Netherlands? “Certainly not! Concrete can be found in numerous small-scale applications, such as cycle paths, bus stops and roundabouts. Furthermore, did you know that underneath the asphalt top layer in the Netherlands there are also several dozen kilometres of concrete pavements,” says Wim Kramer, former Technical Marketing and Statistics Advisor at Betonhuis (“Concrete House”, regrouping the different cement and concrete associations in the Netherlands).
Oval roundabout – in Nieuw Bergen made of continuously reinforced concrete. The province of Limburg opted for concrete because this material is resistant to the high torsional forces of truck traffic and shows no rutting. For the separate cycle paths concrete has been chosen due to the absence of root heave. The province assumes a lifespan of forty years without much maintenance. Photo: Betonhuis.
“When I am asked, especially by foreign colleagues, how things are going with the concrete road market in the Netherlands, then my answer is: the Netherlands is traditionally an asphalt country”, says Wim Kramer. “That may not always have been the case, but it has been since the nineteen sixties. However, after the oil crisis in the seventies and the associated high oil and bitumen prices, interest in concrete roads also reappeared among clients in the early eighties. In that period there were about twenty concrete road builders in the Netherlands. Nowadays they are about ten”.
According to Kramer, concrete paving is chosen by several clients for different applications. These include cycle paths in the rural areas, roundabouts with relatively high and heavy traffic, truck parking areas and container terminals. “This can, however, differ greatly from one client/manager to another. For example, almost 60% of the roundabouts under the supervision of the Province of Noord-Brabant are made of concrete and, according to my information, some other provinces do not build any concrete roundabouts at all. The Middenpeel-road in Noord-Brabant is also entirely made of concrete because of the high density of freight traffic”.
Wim Kramer, former Technical Marketing and Statistics Advisor at Betonhuis: “A concrete pavement may be more expensive than an asphalt pavement upon purchase and construction. But over a period of thirty years, concrete is cheaper. You don’t have to maintain it and regular replacement is not necessary”. Photo: Betonhuis.
Why do provinces such as Noord-Brabant and Flevoland so often opt for concrete while other provinces almost never do?
“It appears that arguments for choosing asphalt or concrete for one similar application, are differently interpreted or weighed according to each client. Of course, this has also to do with each local situation, a possible unfamiliarity with the material, specificities linked to the demand and/or type of contract”.
According to Kramer, if the choice is made based on the type of contract, the contractor will often also look at what he is good at: “Does he choose asphalt because he has the people, the material and the equipment for it, or does he join forces with a subcontractor such as a concrete road construction company? I often hear from contractors with both an asphalt and a concrete department that there is an internal battle on tenders to include concrete in choices for solutions. If the contract also includes maintenance for a longer period, which side does the choice fall to? A top layer of very open asphalt concrete replaced after ten years and the intermediate layer after fifteen to twenty years. But a concrete paving will last thirty to forty years!”
Yellow concrete bike path near Bennekom. Constructing a bike path in concrete has many advantages. Root heave doesn’t cause any damage and virtually no maintenance is required, making it a sustainable investment. Photo: Betonhuis.
“Probably like many others, I see that the number of criteria to reach a sustainable solution is only increasing. The time when only price was the determining factor is long gone. Other factors such as MEAT (most economically advantageous tender), sustainability aspects such as CO2 reduction, LCC (Life Cycle Costs) and LCA (Life Cycle Assessment) are an integral part of the contractor’s final offer. Recently, circular economy has also been added to the list. The increasing number of criteria does not make it any easier or simpler to compare solutions and requires a great deal of effort and knowledge from both the client and the contractor”.
Kramer also points out that research is taking place to develop road constructions with lower rolling resistance. This can save much more CO2 during the use phase compared to the construction phase of the pavement. “Rolling resistance partly depends on the texture, evenness and stiffness of the road construction. In my opinion, this is a very good development”.
A particular solution is the construction of road widenings in concrete: “Germany has gained a lot of experience with the construction of slow lanes in concrete for freight traffic. The drainage of rainwater through the top layer of open asphalt does, however, require attention. But there are solutions for this, such as a drainage box under the joint between asphalt and concrete. In the Netherlands, some experience has already been gained with the application of concrete against asphalt in the entry and exit lanes of motorways.
Concrete bus lanes have been built on the Huizinga-avenue in Eindhoven. The bus lanes are made of doweled jointed plain concrete pavement (JPCP) with a brushed surface. The main contractor for this project is KWS Infra and the concrete pavement for the bus lane has been constructed by the company Den Ouden. Photo: Betonhuis.
The most used pavement base layer in the Netherlands is an unbound base consisting of a layer of mixed aggregate on top of a layer of sand. The concrete layer is applied on top of this foundation. The pavement is often provided with joints at regular intervals (a few metres) in order to absorb volume changes and forces resulting from expansion and contraction forces in the concrete. Usually the slabs are held together by dowels to prevent height differences and excessive forces on the edge of the slabs.
Fibre-reinforced concrete can also be used in dowelled JPCP. In that case dowels are placed at 1/3 of the thickness of the concrete, measured from the bottom. When (continuously) reinforced concrete is used, an intermediate layer of 50 mm asphalt is applied. This layer helps placing and positioning the reinforcement as well as obtaining a uniform thickness of the concrete pavement during execution. For heavy and medium loaded roads, continuously reinforced concrete can also be chosen.
Concrete pavements are generally mechanically poured by machine, allowing high daily production rates. Kramer adds: “It is also important to know that concrete can easily be reused afterwards. An old damaged pavement structure can be recycled, even after a long lifetime. The concrete is then broken up and crushed into aggregates of the wanted gradings. The recycled concrete aggregates can be used entirely as aggregate in new concrete for a new cycle path, for example. Concrete thus remains in the chain and is reused sustainably”.
It isn’t noticeable from the user’s point of view, but the Netherlands covers several tens of kilometres of concrete pavements under a top layer of asphalt. This structure often involves a continuously reinforced concrete construction (CRCP) built on an unbound base layer. The intermediate layer between the base layer and the concrete pavement is also in asphalt. Due to noise requirements, a top layer of very open asphalt or a two-layer system of very open asphalt is placed directly on the continuously reinforced concrete. This modern concrete pavement has been applied by Rijkswaterstaat on the A50 between Oss and Eindhoven, on the A5 at Schiphol and on parts of the A73 between Venlo and Maasbracht.
Concrete and asphalt react very differently to temperature fluctuations. A SAMI layer (Stress Absorbing Membrane Interlayer) is applied to prevent cracks in the asphalt. SAMI is a stress absorbing intermediate layer of highly modified bitumen. This layer ensures that the forces are absorbed and redistributed under the asphalt. This prevents any crack formation in the asphalt layers.
Roundabout in fibre reinforced concrete at the T-junction N625 (John F. Kennedybaan) – Beatrixweg in Lithoijen. Because of the absence of reinforcement bars, the execution is quicker. Also, if the fibre-reinforced concrete is poured correctly, the formation of cracks is reduced. Client: Province of Noord-Brabant; Contractor: Den Ouden Groep. Photo: Betonhuis.
“The drainage requires particular attention. The concrete pavement is, by essence, water proof. With a top layer of very open asphalt concrete you have to make sure that the road surface can be drained to the sides. In the case of concrete, you have to make sure that the water can infiltrate into the soil somehow. E.g. by draining it through a drainage pipe. Incidentally, concrete paving can also be done in an ‘open’ variant, where the water can flow away through the pavement, just like with very open asphalt concrete. It is called pervious concrete,” says Kramer.
Concrete pavements are also very appropriate for roundabouts, where centrifugal and torsional forces are applied on the pavement. And on this configuration, freight traffic is an even heavier load. “In Germany, around 650 concrete roundabouts have already been built in the past few years. The Netherlands has an estimated 150 concrete roundabouts, including turbo-roundabouts,” says Kramer. A “turbo” roundabout is a roundabout with two separate lanes. The desired lane is chosen before entering the roundabout. Most of the heavily loaded concrete roundabouts are built in continuously reinforced concrete. A recent development is the use of fibre-reinforced concrete. Compared to unreinforced concrete pavement, the thickness is reduced, and the number of transverse joints can be reduced 4 to 8 times (depending on the number of connecting roads).
Many single-lane roundabouts are also made of concrete. A new development is the use of precast concrete slabs. In September 2017, the first prefab modular roundabout was built at a heavy traffic intersection in Ermelo. The construction of this ‘Protonde’ took only two days. The precast concrete elements include the apron, the access roads and on and off ramps as a connection to the asphalt. Also, quality base layer helps avoiding differential settlement as well as extra load on the joints.
In the Netherlands, concrete pavements are also regularly used for bus stops, bus lanes and bus stations. This choice is made from the point of view of comfort, durability, and accessibility. In some cases, bus stations are also constructed in continuously reinforced concrete pavement (CRCP), but the most common structure for bus infrastructure is dowelled JPCP.
In September 2017 the first precast modular roundabout has been built at a busy junction in Ermelo. The construction of this ‘Protonde’ took only two days. The precast concrete elements include the apron, access roads and exit ramps connected to the asphalt.
In the Netherlands we find more and more concrete cycle paths. Kramer: “A cycle path made of concrete has many advantages over other paving materials. Think of durability, maintenance and safety. In Flevoland, 350 km of asphalt cycle paths will be replaced by concrete cycle paths in the coming years! Fibre-reinforced concrete can also be used, so that the construction thickness can remain thinner. Synthetic fibres will then be used.
According to Kramer, sustainability has become increasingly important in recent years: “A cycle path constructed according to the current design and implementation rules has a lifespan of at least fifty years. During this period, the surface will continue to meet the requirements of all users, i.e. remains smooth and sufficiently rigid. The texture of the surface of such a concrete cycle path does not wear off through use either. Therefore, concrete hardly requires any maintenance during its service life. The construction is also strong enough to withstand tree roots and other invasive vegetation”.
Another advantage is that concrete naturally has a light colour. As a result, the surface of a concrete cycle path always remains clearly visible, especially in outdoor areas without public lighting. “But other colours are no problem either. Adding an appropriate amount of pigment to the concrete mixture ensures almost any wanted colour. The colour will clearly distinguish the cycle path from other pavements. Outside urban areas the use of pigments is usually discouraged. Here, the natural light concrete colour already increases safety sufficiently”.
Wim Kramer also points to the widespread use of concrete safety barriers as temporary and permanent separation of lanes. Safety barriers are also suitable for preventing lorries from ending up on the lanes in the opposite direction in the event of an accident. They also screen off obstacles, such as bridge pillars and tunnel walls. Barriers can consist of precast elements, but they can also be cast on site using a slipform paver.
Kramer concludes with an appeal to municipalities and provinces to look primarily at the long term: “A concrete pavement may be more expensive than an asphalt pavement upon purchase and construction. But over a period of thirty years a concrete paving will be cheaper. You don’t have to maintain it and regular replacement is not necessary. Think also of traffic jams during maintenance. And how much CO2 emissions are produced? Not only because of the maintenance work, but also because of traffic diversion. But yes, an alderman prefers to score on the delivery of a road. He or she will be retired in thirty years’ time. Our message from Betonhuis is therefore: “Think in the long term and make sure you know what you are asking for”!