Mechanical performance of reinforced concrete with different proportions and lengths of Basalt Fibres

This paper discusses the effect of the fraction (0.2-0.3% by volume) and length (22 mm and 24 mm) of basalt fibre on the mechanical properties of concrete. The paper aims to evaluate the effect of different combinations of basalt fibres on the mechanical properties of concrete, as well as identify the best basalt fibre length and content that have the optimum influence on concrete. This paper is considered to be distinct from other research work as it fills the literature gap by presenting new unknown facts and also adds new knowledge. For example, it identifies the best basalt fibre length and content combination that demonstrates an improvement in the mechanical properties of concrete. It suggests the use of a blend of 12 mm short and 24 mm long fibres as they have a significant effect on the mechanical properties of concrete, it validates the results obtained from the laboratory by using a statistical analysis of variance ANOVA software, as well as determine the correlation between the mechanical properties of concrete. The results showed that the optimum basalt fibre length and content that enhanced the mechanical properties of concrete is 24 mm long fibre with content of 0.2% by the total volume of concrete. It also show that changing basalt fibre length and content enhance not only both tensile and flexural strengths of concrete, but also reduce its compressive strength, workability and air content of concrete, as well as maintain the unit weight and modulus of elasticity values. In this context, the incorporation of basalt fibres within the mixture becomes an important parameter for strengthening concrete in the construction industry

Effect of Material Stiffness Variation on Shakedown Solutions of Soils Under Moving Loads

Shakedown limits of pavements and railway foundations can be calculated based on shakedown theorems. These values can be used to guide the thickness designs of pavement and railway constructions considering material plastic properties. However, most existing shakedown analyses were carried out by assuming a unique stiffness value for each material. This paper mainly concentrates on the influence of stiffness variation on the shakedown limits of pavements and railway foundations under moving loads. Finite element models as well as a user-defined material subroutine UMAT are first developed to obtain the elastic responses of soils considering a linearly increasing stiffness modulus with depth. Then, based on the lower-bound shakedown theorem, shakedown solutions are obtained by searching for the most critical self-equilibrated residual stress field. It is found that for a single-layered structure, the rise of a stiffness changing ratio will give a larger shakedown limit; and the increase is more pronounced when the friction angle is relatively high. For multi-layered pavement and railway systems, neglecting the stiffness variation may overestimate the capacity of the structures

Effect of asphalt mixture compaction on stability and Volumetric properties of ACW14

This paper investigates the influence of Marshall Compaction (50 and 70 blows) on the Stability and Volumetric Properties of ACW14 asphaltic concrete mixes. The samples were prepared according Marshall Mix design method. The properties studied were resilient modulus, air voids, bulk density and stability. The results of this study indicate that 75 compaction yield the highest Marshall Stability value and lower bitumen content. The study concluded that mixtures subjected to 75 compaction blows show better performance than the mixtures subjected to 50 blows

Recent Progress on Lower-Bound Shakedown Analysis of Road Pavements

Shakedown theory has been recognised as a more rational basis for structural design of flexible road pavements. A lower-bound shakedown approach, which aims to find the maximum design load of a pavement structure, was developed by the University of Nottingham, that forms part of efforts among other researchers’ in applying shakedown theory in pavement designs. The lower-bound shakedown solutions were consistent with existing shakedown solutions assuming that the materials are isotropic and homogeneous following an associated plastic flow rule. Recently, this lower-bound approach was further developed to consider more realistic cases. Both two-dimensional and three-dimensional shakedown analyses were carried out taking into account cross-anisotropic or heterogeneous materials, the properties of which were programmed into a finite element software ABAQUS. For pavement materials obeying a non-associated flow rule, the corresponding two-dimensional lower-bound shakedown limits were also estimated by extending the lower-bound shakedown approach. A numerical step-by-step approach was also applied to address the non-associated problems and obtained similar results. Through these studies, influences of the original assumptions on the shakedown-based pavement designs can be assessed