Lambert Houben

Compressive and Indirect Tensile Strengths of Cement-Treated Mix Granulates with Recycled Masonry and Concrete Aggregates

AbstractReuse of construction and demolition waste (CDW) as a road base material is one of the effective methods to reduce environmental effects caused by CDW dumping in landfills. To explore the feasibility to reuse CDW as a cement-treated material, this paper investigated the compressive and indirect tensile strengths of cement-treated demolition waste. Because the recycled CDW is a mix of recycled masonry and concrete, different ratios of recycled crushed masonry-concrete aggregates by mass were chosen in this study. Four mixture variables (cement content, degree of compaction, masonry content, and curing time) and their influence on the mechanical properties of cement-treated mix granulates (CTMiGr) were then considered. Experimental results showed that a general model to estimate the compressive and indirect tensile strengths of CTMiGr can be established in relation to those four mixture variables. Compared with normal cement-treated granular materials, the masonry content is another unique factor to...

Application of aging methods to evaluate the long-term performance of road bases containing blast furnace slag materials

The long-term performance of secondary materials is becoming a challenging aspect in road construction since their future behaviour is difficult to estimate. In this study, aging is proposed as a means of exploring the long-term mechanical and physical performance of secondary materials. A Blast Furnace Slag (BFS) mixture which is routinely used in the Netherlands in road base construction, e.g. in the A32 motorway, was selected as a reference material. Twenty years after its construction, the A32 pavement structure experienced serious failure and the BFS base contributed to that. Accordingly, an aging protocol was suggested to detect at an early stage potential poor material performance. Two types of accelerated aging approaches were applied to the materials being steam aging and cyclic freezing and thawing. The results show that there is a linkage between the material performance and temperature, moisture, chemical composition and time. The response behaviour, of aged laboratory samples and the field-aged A32 base material, suggested that the aging methods did a reasonable job in detecting materials with a poor performance.

Characterization of Unbound Granular Materials Using Repeated Load CBR and Triaxial Testing

Because repeated load triaxial testing is cumbersome and not readily available, especially in developing countries, characterization of unbound granular road base and subbase materials is still done using empirical methods such as California Bearing Ratio (CBR) testing. Although widely applicable and useful, the CBR does not provide information on the mechanical behavior such as the resilient and permanent deformation characteristics of the material. A relatively simple testing technique, a repeated load CBR test, is developed to characterize the mechanical behavior of unbound base and subbase materials, which can be used as an input in mechanistic design analyses. The repeated load CBR test is quite useful to estimate the mechanical behavior of unbound granular materials, especially the resilient modulus. Furthermore, big scale cyclic triaxial tests are carried out to measure the resilient modulus which is then compared with the repeated load CBR results.

Cracking Behavior of Continuously Reinforced Concrete Pavements in Belgium: Characterization of Current Design Concept

Continuously reinforced concrete pavements (CRCPs) have been used in Belgium on a large scale for more than 40 years. Under the initial standard design concept, an apparently unfavorable cracking pattern develops with a high probability of clusters of closely spaced cracks. The standard design underwent several changes addressing longitudinal reinforcement rate, depth of the reinforcement layer, presence of an asphalt interlayer, pavement thickness, concrete mix, surface finishing, and lane width. The current concept has been used since 1995, and no major distresses have occurred since then. Research was undertaken to investigate crack spacing and crack width characteristics of CRCPs under the current design concept with a focus on the influence of the differing reinforcement percentages on early-age cracking behavior of CRCPs. Several approaches were used for analysis of crack spacing, especially the probability of clusters of closely spaced cracks. Crack width data including the movement of the slab were obtained with linear variable differential transformer measurements.

Innovative Longitudinal Joints Between New and Old Porous Asphalt

For both lane and carriageway wide maintenance of Porous Asphalt (PA) in the Netherlands, contractors increasingly make use of so called joint protectors to prevent premature damage to longitudinal joints in the warranty period of 7 years. Mostly strips of bituminous material are placed on those joints or the joints are poured with hot bitumen and sanded, but sometimes no measures are taken. Those joint protectors can eventually go smooth and/or shiny. Rijkswaterstaat (RWS) gets relatively many complaints of especially motorcyclists, because they are more vulnerable and driving in the middle of the lane where sometimes the joint is. Claims are also made. Sometimes joint protectors are mistaken for “ghost” marking, especially during rainfall, because they are more visible than the mark. In short, RWS was not satisfied with the current joint protectors. In order to remedy this, RWS started a competition to come up with improvements. Contractors came with 11 ideas that were assessed on skid resistance, shine, traffic hindrance, environmental friendliness and costs. Five winners were selected by an independent jury. Those prize winners were able to demonstrate their idea on a PA test section on motorway A59. Cores from these test sections, drilled on the joint, were investigated in the laboratory. One year after construction the joints were visually inspected, and the skid resistance and horizontal water drainability was measured. This paper discusses the winning ideas, the construction of the test sections, the laboratory and field tests and results.

New Model for Longitudinal Tracking in Non-jointed Plain Concrete Pavements

Houben has developed a model concerning the transversal cracking in non-jointed plain concrete pavements using equations from the standard Eurocode 2 for the time-dependent concrete properties and shrinkage. For properties that are not available in standards, Houben made assumptions based on engineering judgment. After that, Pradena and Houben studied those assumptions more in depth, including the maturity method. The results were compared with field measurements and a new equation for the relaxation factor was proposed. The objective of the present paper is to apply those findings for analysis of the longitudinal cracking process in non-jointed plain concrete pavements taking into account different conditions. The calculation results include the time of occurrence of longitudinal crack(s), if any, the variation of the crack widths and the maximum pavement width that can be constructed without any longitudinal joint. In the cases that a longitudinal crack occurs, it is always only one crack which occurs at early age. Because differences in the relaxation at this age are fundamental, future analyses need to concentrate at early age. The new approach confirms the complexity of this kind of modelling, improves the analysis from a theoretical point of view, and yields new insights for future investigations.

Monitoring Early-Age Cracking of Continuously Reinforced Concrete Pavements on the E17 at Ghent (Belgium)

Continuously reinforced concrete pavements (CRCP) are frequently applied on motorways and also on other heavily trafficked roads in Belgium, mainly because of the confidence in its durability. An exposed aggregate surface is used to reduce the traffic noise. The durability, the sustainability, the low maintenance and the low traffic noise production of CRCP lead to long-lasting applications in Belgium. This paper presents the observations and findings from the monitoring of three CRCP test sections constructed on the motorway E17 near the city of Ghent, Belgium in August 2011. The three test sections have a reinforcement rate of 0.75%, 0.70% and 0.65% + 20 kg/m³ steel fibers, respectively. Right from the moment of construction, the behavior of the pavements was monitored for the concrete temperature, the crack spacing and the crack width, and the development of the crack pattern in time. The temperatures within the concrete were evaluated using thermocouples. The crack spacings were measured with a distance measuring wheel. The width of a number of cracks was measured with a microscope and the movements within the CRCP were also measured with a linear variable differential transformer (LVDT) across a number of cracks. Major observations and findings from the monitoring of the CRCP test sections include: the effect of longitudinal reinforcement on the early-age cracking; the effect of time of construction during the day on the early-age cracking; and the effect of curing time of concrete on the early-age cracking.

Application of the Steam Aging Method to Evaluate the Long-Term Performance of Secondary Materials for Road Construction

Long-term performance of secondary materials is becoming a challenging aspect in road construction because, as a result of their benefits, they are being used on a large scale. The problem with these materials, however, is that their future behaviors are difficult to estimate. In this study, aging is proposed as a means of exploring the long-term mechanical and physical performance of secondary materials. A blast furnace slag (BFS) mixture, which is routinely used in the Netherlands in road (sub-)base construction, was selected as a reference material. A motorway in the Netherlands was used as a source of field-aged BFS materials. The base layer of this motorway suddenly experienced serious failures. To prevent similar problems, an aging method was suggested to detect potential poor material performance at an early stage. The steam aging approach was chosen and applied to the field-aged and fresh materials. This aging treatment has affected material characteristics. This showed that there is a linkage between material performance, mixture composition, and aging conditions.

Modelling the effect of plastic sheet curing on early age temperature development in concrete pavement

ABSTRACT Prediction of the temperature development at an early age is a good starting point to assess the development of the restrained thermal stress and thermal cracking in rigid pavements. This paper presents a numerical early age concrete pavement temperature prediction model. It enables to evaluate the effect of various paving conditions, such as paving time, curing method, air temperature, wind speed, and the concrete placement temperature, on the early age concrete pavement performance. A critical review of current heat flux models at the pavement surface covered with a plastic sheet is presented. An extension of existing models to quantify the effect of the plastic sheet curing method is introduced, based on the energy balance method. The numerical implementation procedure for the proposed temperature prediction model is solved by the finite difference method. The temperature prediction model was verified with field measured data of two test sections. The predicted temperature shows a satisfying match with field measured data. Lastly, the effect of plastic sheet curing and its duration on the development of the pavement temperature was analysed by the proposed theoretical model.

Ride quality stability of jointed plain-concrete road pavements with short slabs

Curling and warping of jointed plain-concrete road pavements are not only unfavourable from the structural point of view but also from a functional perspective because road users can perceive different ride qualities during the day due to changes in slab curvature. The use of short slabs, an innovation of traditional jointed plain-concrete pavements, allows a reduction in concrete thickness due to traffic load configurations and also a reduction in curling and warping. The objective of this study was to compare the stability of ride quality in traditional and short-slab pavements. Using a walking profiler, precise international roughness index (IRI) measurements were taken every 10 m on both types of pavements in Chile at different times of the day and over two slab tracks. Roughness measurements using a high-speed laser profilometer over 12 km of additional short slabs in Chile were also considered. Changes in IRI of up to 0·6 m/km were obtained on traditional pavements. In contrast, the results clearly ...