Abstract. Non-dowelled short slabs are a cost-effective innovation of jointed plain concrete pavements. The development of this innovation has been concentrated in their structural performance. Still there is a lack of specific studies of the relation load transfer -crack width, being the crack width at joint the direct cause of the aggregate interlock. Considering that their provision of load transfer relies on aggregate interlock, the objective of the present article is to develop the relationship between the load transfer by aggregate interlock and its direct cause (the crack width) specifically for innovative nondowelled short concrete slabs pavements. For that, the analysis includes a validated nonlinear aggregate interlock model incorporated in a 3D Finite Element program, laboratory results, and field measurements performed as part of the present investigation. The results show that due to the small crack widths, the short slabs are able to provide adequate load transfer (not less than 70%) even without dowels bars. Indeed, in this case, the load transfer relies on aggregate interlock and the results of the Faultimeter (residual value more than 0) have confirmed this interlocking for crack widths at joints not more than 1.2 mm, which are typical values in short slabs when the joints are activated. For that, the Early Entry saw cutting method needs to be modified or applied as a complementary method to perform the joints. Although in short concrete slabs pavements the provision of load transfer is already guaranteed by the small crack widths at joints, the application of high-quality coarse aggregates provides even higher load transfer.

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Aggregate interlock is the dominant load transfer mechanism in non-dowelled Jointed Plain Concrete Pavements, as the innovative short concrete slabs. Although the Load Transfer Efficiency of this pavement innovation is based on that mechanism, the structural design methods do not relate the Load Transfer Efficiency by aggregate interlock with its direct cause, which is the Crack Width under the joints. The objective of the present article is to characterise in the laboratory the Load Transfer Efficiency−Crack Width relation for innovative short slabs Jointed Plain Concrete Pavements. Additionally, as an alternative to large-scale laboratory tests to study the Load Transfer Efficiency, a practical test on a reduced scale is proposed. The results confirmed that short slabs Jointed Plain Concrete Pavements with high-quality aggregates are able to provide adequate Load Transfer Efficiency (above 70%) without dowels bars. Based on the laboratory results, complemented with previous field data, a Load Transfer Efficiency−Crack Width curve is proposed and made available for structural design methods of short slabs Jointed Plain Concrete Pavements. Finally, the laboratory test on a reduced scale is useful to develop specific Load Transfer Efficiency−Crack Width relations using standard equipment available in traditional concrete laboratories.

Concrete is a material with high compressive strength, but predisposed to shrinkage cracking, rapid cracks propagation, and brittle failures. The incorporation of fibre is an acceptable solution to reduce these limitations. However, high cost and energy consumption related to man-made fibres have placed natural fibres as an attractive sustainable alternative, especially considering that different natural fibres are industrial waste (as the Eucalyptus globulus bark fibre). Still, natural fibres can produce an important reduction of concrete strength. Hence, the objective of this study is to evaluate the effects of Eucalyptus globulus bark fibre in traditional concrete mechanical properties as compressive and flexural strength. For this, an experimental program was developed in such a way that reduces the results uncertainties and increases the power of decision regarding the percentage and fibre conditions of the samples. The results indicate that, unlike other natural fibres, the traditional mechanical properties have a slight reduction and acceptable workability. This fact is more evident in the samples with 0.50% fibre with respect to the weight of cement. Therefore, reinforcing mortars and concrete with Eucalyptus globulus bark fibres emerges as an eco-friendly building alternative to reuse this industrial waste.

The cracks in concrete pavements are formed at early-age as consequence of internal stresses in the concrete. Therefore, the stress relaxation has an essential influence on the cracking process. To model this process allows to identify, for instance, the time for saw-cutting the joints or the cracks width that affects load transfer. Previously, the authors proposed a new equation of the relaxation factor, based on a theoretical and practical analysis of the transversal cracking in jointed plain concrete pavements. The objective of the present paper is to analyze the utility of this new equation of relaxation in the design and construction of jointed plain concrete pavements. For that, other cracking processes in plain concrete pavements (jointed and non-jointed) were modelled with the proposed equation. Wherever is possible the modelling results were compared with observations of the real behaviour of pavements. From the design point of view, with the modelling results of transverse crack width (>1.0 mm) is possible to considerate in the design, optimal slabs length with thinner cracks for better aggregate interlock. And for the longitudinal cracking in jointed plain concrete pavements, the modelling and the field observations, yield cracks width that provide load transfer (0.1 mm). From the construction point of view, the cracking process in non-jointed plain concrete pavements, shows is possible to construct pavements of 7 m width in one gang without cracks risk, and adjustments can be made to a better prediction of the time of occurrence of the 1st transverse cracks.