دانلود رایگان مقاله مدل سازی المان گسسته از رفتار حالت تازه بتن قبلی

Abstract

The objective of this paper is to propose a novel numerical approach to evaluate the fresh state behavior of pervious concrete (PC). A new constitutive law applied to Discrete Element Method was developed for the simulation of the interaction between aggregates connected by fresh cement paste. Several innovative aspects regarding the type of contact model, the consideration of the contact bridge and the inclusion of the rheology coefficients were proposed. A calibration was performed with data from the literature. Furthermore, an extensive experimental program considering different shapes of aggregates, grading curves and aggregate-to-cement paste ratios was conducted to evaluate the fresh state behavior and validate the numerical models. The good fit obtained between numerical and experimental results confirm the model and the constitutive law reproduce the under uniaxial compaction, thus representing a step forward in the design and application of pervious concrete mixes.

8. Conclusions

The following conclusions are derived based on the numerical and experimental studies conducted in this work. • The experimental results of the compaction of pervious concrete produced with spherical aggregates showed that the influence of the P/ A over the compaction curve is negligible. The application of the numerical models proposed here explained this observation, suggesting that the small variations induced by the P/A are eclipsed by the high variability of the results. • The experimental study of the compaction of pervious concrete in fresh state produced with crushed limestone in two different grading (5–12 mm and 9–20 mm) showed that lower pressure was necessary to compact the specimens with bigger size of particles. This phenomenon is related to the number of contacts between aggregates, which is inversely proportional to the size of particles. The same trend was also observed in the new models developed here to simulate the compaction of pervious concrete. • Although the Kelvin-Voigt rheological model is generally used to represent the interaction between aggregates surrounded by cement paste in fresh conventional concrete, it might lead to important inconsistencies when the contact between particles of pervious concrete is simulated. To overcome these inconsistencies, the constitutive law proposed and validated here should be used. • The new constitutive law reproduced the normal behavior of the contact between two identical spheres with a visco-elastic material in the middle (experiments conducted by Shyshko et al. [21]) with accuracy. The comparison of the numerical and experimental results for equivalent displacements showed a correlation coefficient (R2 ) of 0.975, 0.97, 0.936, 0.947 and 0.935 for the velocities of approximation of 200, 100, 50, 20 and 10 mm/min, respectively.