Innovatieve naadbeschermers bij ZOAB inlagen

Voor bij zowel rijstrook- als rijbaanbreed onderhoud aan Zeer Open AsfaltBeton (ZOAB) worden door aannemers steeds vaker zogenaamde naadbeschermers toegepast om vroegtijdige schade aan langsnaden in de garantie periode van 7 jaar te voorkomen. Meestal worden bitumineuze strips aangebracht ter bescherming of worden naden afgegoten met hete bitumen; soms worden geen maatregelen genomen. Deze naadbeschermers kunnen uiteindelijk te glad worden en/of gaan glimmen. Rijkswaterstaat (RWS) krijgt over slecht acterende naadbeschermers relatief veel klachten van met name motorrijders. Deze groep is kwetsbaarder en motorrijders rijden in het midden van de rijstrook, waar soms de naadbeschermers zich bevinden. Soms worden de naadbeschermers ervaren als “spookmarkering”, vooral tijdens regenval omdat ze eerder zichtbaar zijn dan de markering. Kortom, RWS was niet tevreden over de huidige generatie naadbeschermers. Om deze problemen te verhelpen heeft RWS de aannemerij d.m.v. een wedstrijd uitgedaagd om met verbeteringen te komen. De aannemers kwamen met 11 innovatieve oplossingen, die door een onafhankelijke deskundige jury werden beoordeeld op de stroefheid, glimmen, verkeershinder tijdens aanbrengen, milieuvriendelijkheid en kosten. Er werden vijf winnaars geselecteerd, die door RWS in staat werden gesteld om hun idee in een proefvak (ZOAB inlage) op de autosnelweg A59 te demonstreren. Uit deze proefvakken werden op de naad kernen geboord, die op kosten van RWS werden onderzocht in het laboratorium. Eén jaar na het inbouwen van de naadbeschermers werden deze visueel geïnspecteerd en zijn de stroefheid en horizontale waterdoorlatendheid gemeten. In deze paper wordt ingegaan op de winnende innovatieve naadbeschermers, wordt de inbouw ervan besproken en worden de testmethoden en –resultaten weergegeven

Joint faulting behaviour of innovative short concrete slabs

Pavements are one of the largest assets of a city and their functional condition (ride quality) is priority for their clients. In jointed plain concrete pavements (JPCPs), the presence of joint faulting (JF) reduces the ride quality. Today, short slabs are available as a cost-effective JPCP innovation. The objective of this paper is to analyse the JF behaviour of JPCPs with short slabs. For this, a deterioration model to predict it and trends of JF observed in short slabs of Chile and the United States are considered. The HDM-4 model always yields lower JF per joint in short slabs than in traditional ones. However, real-world short slabs show not only lower JF per joint (that the modelled JF), but also that more joints do not necessarily mean more JF per length of pavement that affect the ride quality. One of the relevant explanatory factors for it is the radical reduction of crack width at joints, which produces a fundamental increase of the load transfer efficiency. To maintain favourable behaviour observed in the field it is recommended to assure joint activation and to provide adequate stiffness of the layers below the short slabs

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

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.Pavement Engineerin

Joint faulting behaviour of innovative short concrete slabs

Pavements are one of the largest assets of a city and their functional condition (ride quality) is priority for their clients. In jointed plain concrete pavements (JPCPs), the presence of joint faulting (JF) reduces the ride quality. Today, short slabs are available as a cost-effective JPCP innovation. The objective of this paper is to analyse the JF behaviour of JPCPs with short slabs. For this, a deterioration model to predict it and trends of JF observed in short slabs of Chile and the United States are considered. The HDM-4 model always yields lower JF per joint in short slabs than in traditional ones. However, real-world short slabs show not only lower JF per joint (that the modelled JF), but also that more joints do not necessarily mean more JF per length of pavement that affect the ride quality. One of the relevant explanatory factors for it is the radical reduction of crack width at joints, which produces a fundamental increase of the load transfer efficiency. To maintain favourable behaviour observed in the field it is recommended to assure joint activation and to provide adequate stiffness of the layers below the short slabs.Pavement Engineerin

Innovations in concrete pavements for a sustainable infrastructure

Concrete pavements (CPs) are durable and they do not need periodic invasive maintenance interventions. Nevertheless, CPs are hardly chosen when only initial costs, instead of life-cycle costs, are considered in the evaluation. Nowadays, there are innovations in Jointed Plain Concrete Pavements (JPCPs) that reduce initial costs about 25% with respect to alternatives with equivalent structural capacity. This paper addresses the question if the innovations early-entry saw-cutting of joints, joints without seals and shorter joint spacing (without dowels bars) are able to maintain the traditional life-cycle performance of CPs. All these innovations affect the joints of the JPCP, and these ones the JPCP performance. Accordingly, the objective of the present paper is to analyse the effects of the joints behaviour on the performance of the JPCPs innovations. The joint behaviour is characterized by the joint activation and opening, the joint capacity to transfer traffic loads and the joint deterioration. The calculations of the joints activation and opening are made with a model developed by the authors. For the estimation of the joint transfer capacity; the results of finite-element software are used. The analysis is completed with field data of the JPCPs innovations. The innovations analysed contribute to a sustainable infrastructure as they can maintain, and even improve, the traditional life-cycle performance of CPs with lower initial costs. Nevertheless, for the design hypotheses to be valid, it is necessary to assure the joints activation and to limit the joints opening to 1.2 mm. With this purpose, for the analysed conditions, it is recommended to cut the joints at least at 30% of the JPCP thickness.Structural EngineeringCivil Engineering and Geoscience

Uncracked joints in plain concrete pavements: causes, effects and possibilities of improvements

During the construction of Jointed Plain Concrete Pavements (JPCPs) in Chile, it was observed that joints remained uncracked. The objectives of this paper are to evaluate the effects of uncracked joints (UnCrJ) in JPCPs and to propose possible solutions or improvements to avoid or minimize this phenomenon. Considering low thermal amplitude as cause of UnCrJ, a rational-based, detailed and empirically validated model is used to predict UnCrJ and crack width. The modelled results are not only due to material changes but also to the location of the series of cracks in time in the JPCP system. The paper contributes with this rational approach, instead of an empirical-simplified one, to achieve the objectives. For the modelled conditions, the “as-built” slab length range is 8 m to 56 m instead of the 4 m designed one. Then, more curling, joint faulting, water infiltration in sealed joints and load transfer efficiency ≤ 70% are expected.The alternative solutions proposed are associated to innovations as short joints spacing, unsealed joints and saw-cuts up to 50% thickness made with thin blade (≤ 3mm), which was verified with new field evidence provided in the article.Pavement Engineerin

Determination of fracture energy of early age concrete through a uniaxial tensile test on an un-notched specimen

Unlike the notched specimens for conventional concrete fracture tests, this paper introduces a deformation-controlled uniaxial tensile test on an un-notched specimen. The surface of the dog bone-shaped specimen is a second order parabolic curve, and the gradual change in the specimen shape does not lead to extreme stress concentrations. Another significant feature of the tension test set-up is that it is built with three hinges, to accommodate the alignment of the specimens. The specimen preparation, test conditions, and the tension test set-up are explained in detail. The fracture energy of the concrete is determined by the obtained complete softening curves. The fracture energy is found to increase with age, going towards a horizontal asymptote as concrete hardened in a tested age range of 1 day to 90 days. Moreover, the rate of development of the fracture energy was found to be higher when compared to tensile strength and stiffness.Pavement Engineerin

Application of aging methods to estimate long term performance of secondary materials for road construction

Long term performance of secondary materials is becoming a challenging aspect in road construction since due to their benefits they are being used on a large scale, but on the other hand 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. The A32 motorway in the Netherlands was used as a source of field aged granulated BFS materials. The base layer of this motorway, suddenly experienced serious failure. Different failure mechanisms have been hypothesized. In order to estimate future behavior of secondary materials and to prevent similar problems to occur an aging protocol was suggested to detect at an early stage potential poor material performance. Two types of aging approaches were chosen and applied to the field aged and fresh materials being steam aging and cyclic freezing and thawing. Both aging treatments have affected mechanical and chemical characteristics. The study of response variables showed there is a linkage between compressive strength, expansion, micro cracking and amount and type of binder.Structural EngineeringCivil Engineering and Geoscience

Experimental evaluation of load transfer efficiency of non-dowelled concrete pavements

Generally, joint performance in concrete pavements is evaluated in laboratory by applying dynamic loads that require large scale experimental setups. In order to propose a simplified laboratory test, a comprehensive literary review of the fundamentals of load transfer at joints is made, and the load transfer efficiency obtained via a reduced scale test is compared under static and dynamic conditions. The results confirm feasibility of static analysis via a reduced scale test for evaluating load transfer efficiency of non-dowelled concrete pavements.Pavement Engineerin