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Utrecht, Netherlands

Jacobs M.M.J.,BAM Wegen | De Bondt A.H.,Ooms Civiel | Hopman P.C.,KOACNPC | Khedoe R.,Ooms Civiel
RILEM Bookseries

A test procedure has developed where the crack growth parameters of an asphalt concrete mixture can be determined easily and uniformly. The semi circular bending (SCB) test is the basis of this procedure. However, in this procedure SCB-specimens with a base length of 225 mm are used instead of 150 mm as is indicated in EN 12697-44. In this way the total crack length increases and this is beneficial for the repeatability and reproducibility of the test results. The tests are force controlled with a haversine as loading signal. The length of the crack is measured indirectly by using a crack opening displacement (COD) gauge over the notch, which is situated in the centre of de base of the SCB-specimen. With finite element simulations, the relationship between the COD and the crack length and the stress intensity factor K are determined. All the information is used to determine the Paris' parameters A and n of the tested mixture. The (draft) procedure has been used by two laboratories on two asphalt concrete mixtures. It is concluded that with the test procedure appropriate crack growth parameters can be determined with acceptable values for the repeatability and reproducibility of the test results. In the paper the test procedure will be presented. Also information on the tested materials and test results will be incorporated. © RILEM 2012. Source

Gaarkeuken G.,Ballast Nedam Asfalt | Sluer B.W.,MNO Vervat | Jacobs M.M.J.,BAM Wegen
Four-Point Bending - Proceedings of the 3rd Conference on Four-Point Bending

The fatigue and stiffness properties of cement treated granular base layers have a significant influence on the design of a pavement. Ballast Nedam Asfalt has investigated the possibility of using four point bending tests to determine the functional properties of conventional AGRAC (cement treated reclaimed asphalt as specified in the Dutch Standard, with approximately 2% cement). Four point bending tests on material cut from a pavement and on laboratory made AGRAC have been done. Influences of testing procedure, dimensions of the prismatic beams, strain value, clamping and others are analyzed. Comparable tests have been carried out by BAMWegen and Ballast Nedam Asfalt on laboratory made cement treated sand. The European Specifications for bituminous mixtures EN 12697-24 (Resistance fatigue) and EN 12697-26 (Stiffness) are used for the tests. The research has resulted in a protocol for testing and processing of the functional properties from the test results. © 2012 Taylor & Francis Group, London. Source

Thijssen G.J.,Technical University of Delft | Schott D.L.,Technical University of Delft | Demmink E.W.,BAM Wegen | Lodewijks G.,Technical University of Delft
Energy Efficiency

In the field of bulk solids, handling knowledge on moisture behaviour in aggregate stockpiles can be useful for process optimisation in terms of energy consumption. In the asphalt industry, an increase in moisture content leads to a significant increase in energy consumption. To determine the characteristics of moisture behaviour, correlations are investigated between theory on soil-water movements and moisture in aggregates. With column drainage experiments with porous bottom, similarities between theory and practice are found. This allows the use of theoretical hydrologic models to determine and predict the moisture behaviour in drained piles. The effect of process alterations within the system of piles on energy consumption was investigated, and a significant reduction of energy consumption was found. © 2010 The Author(s). Source

Huurman M.,BAM Wegen | Pronk A.C.,ACP Consultancy
Four-Point Bending - Proceedings of the 3rd Conference on Four-Point Bending

Asphalt stiffness and fatigue properties are important inputs for a mechanistic pavement design. In the Netherlands these properties are traditionally determined by 4 Point Bending tests (4PB). In this paper the accuracy of that test is discussed on the basis of Finite Element Modelling (FEM) for a specific 4PB device. It is shown that application of the European-standard results in an underestimation of the stiffness by 3.2% (at 7500MPa) and an underestimation of the phase lag by 0.4° (lag=20° and 20 Hz.). It is shown that a thorough FEM analysis of the 4PB may reduce these errors to a stiffness that is underestimated by 0.88% and a phase lag which is overestimated by 0.1°. This project emphasizes the benefits of a FEM modelling of a 4PB device in combination with calibration tests. © 2012 Taylor & Francis Group, London. Source

Kluttz R.Q.,KRATON Polymers | Jellema E.,KRATON Polymers | Woldekidan M.F.,Technical University of Delft | Huurman M.,BAM Wegen
Airfield and Highway Pavement 2013: Sustainable and Efficient Pavements - Proceedings of the 2013 Airfield and Highway Pavement Conference

Porous asphalt pavements with a large percentage of air voids such as open graded friction courses (OGFC) have been built across the United States since the 1950s. The OGFCs have several benefits such as a higher degree of friction and permeability providing drainage of rain water from the surface of the pavement. However, only a few cold winter nights can cause years' worth of raveling damage to a road when stresses due to traffic loads and day to night temperature variations reach the binder's breaking point. Delft University of Technology developed a finite element model, the Lifetime Optimization Tool (LOT), to study this phenomenon by predicting asphalt mix response from asphalt mortar properties. Mortars of long-lasting porous asphalt roads were compared with those from early-failure roads. The study concluded that two factors are critical to prevent winter damage: ≤ Limited binder stiffness at low temperature, particularly after aging ≤ Binder stress relaxation at these low temperatures. In a search for improved binder performance, four different highly modified binders were produced by Kraton Polymers Research B.V. Master curves were developed on laboratory-aged binders for viscoelastic properties, and the mortar performance was evaluated at different temperatures and temperature fluctuations using the protocol of the LOT model. The results were compared with literature data of the existing road sections and showed a dramatic improvement in raveling resistance. The SBS polymer-modified binders demonstrated exceptional performance in the winter and at least an equally good performance under summer conditions. © 2013 American Society of Civil Engineers. Source

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