Analysis of stress relaxation in jointed plain concrete pavements

Abstract

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.

Load Transfer-Crack Width Relation of Non-Dowelled Jointed Plain Concrete Short Slabs

“…the base begins to influence the LTE only since crack widths 2.5 mm. According to Davids and Mahoney (1999) and Pradena and Houben (2015) the crack width in traditional slabs JPCPs is, in general, not more than 2.5 mm. In the case of short slabs the crack width is even narrower, generally not more than 1.2 mm (Pradena & Houben, 2016).…”

Influence of early-age behaviour on structural design of sustainable thinner concrete slabs

“…In this section, only a brief description of the model is provided. The details of the model can be found in Houben [17,18], Pradena [19] and Pradena and Houben [20,21]. The basic formulation is that the tensile stresses that occur in a JPCP are caused by restricted deformation, as predicted by Hooke's law, but are influenced by the viscoelastic behaviour of the concrete (relaxation) (1) where E(t) is the time-dependent modulus of elasticity of the concrete (MPa), ε is the total time-dependent JPCP tensile strain due to shrinkage and thermal effects (-), R is a relaxation factor (viscoelastic JPCP behaviour) (-), and g is an enlargement factor (-).…”

“…Pradena and Houben [16] developed the relationship between the load transfer and crack width (at joints) specifically for innovative non-dowelled short concrete slabs pavements. Houben [17,18], Pradena [19] and Pradena and Houben [20,21] developed and calibrated a model to predict crack widths at the joints of traditional JPCPs. The aim of this study is to validate that model using short slabs to obtain the relationship between crack width and LTE in order to incorporate the early-age concrete behaviour in the structural design of short slab JPCPs.…”

Laboratory Characterization of The Load Transfer-Crack Width Relation for Innovative Short Concrete Slabs Pavements

“…The lateral cracked beam sections are adjusted concerning the central section to obtain the CW of interest for the research. In this way, CW of 0.5 mm, 1.5 mm and 2.5 mm are formed, which cover the spectrum of CW found in JPCPs (Davids & Mahoney, 1999;Pradena & Houben, 2015). In the case of short slabs, the CW should be 1.5 mm as a maximum when the joints are activated, the slabs are effectively shorter than traditional ones, and then the design hypothesis (and benefits) of the short slabs are real (Pradena & Houben, 2016).…”