Investigation on performance characteristics of dense graded hot mix asphalt with RAP and Crumb Rubber

The use of recycled materials in asphalt mixtures such as reclaimed asphalt pavements (RAP) have become widely accepted as a replacement for virgin asphalt binder or virgin aggregates. In this study, the RAP content was 30%, and CR additives were blended with the soft unmodified binder by using dry processes. The objective of this study was to investigate and evaluate the engineering properties of dry method application of crumb rubber influences on reclaimed asphalt pavement (RAP) mixtures. To evaluate the effect of rubber-bitumen interaction on the mixture’s mechanical properties, a laboratory investigation has been conducted on a range of dense graded and 30% RAP by dry process crumb rubber modified (CRM) asphalt mixtures containing 0% (control), 1% crumb rubber by the total aggregate mass. The experimental program in this research include the binder extraction for estimating the amount of aged binder in the both fine and coarse RAP material. Before extracting the binder the RAP sieve analysis, have been done to provide the Black grading curve. In continue after the binder extraction the material sieved again to providing the white curve. The comparison of Black and White curve indicated that there is a remarkable difference between the aggregate grading even for the fine RAP. The experimental program was continued by fabricating 12 specimens in different 4 types of mixtures. For the first group no RAP, no rejuvenator and no crumb rubber were used. For the second group 30% of virgin aggregates substituted by RAP material and the third group was similar to the second group just with 0.01% rejuvenator. the forth group was the group, which in that the specimens contain RAP, rejuvenator and crumb rubber. Finally the specimens were tested for Indirect tensile strength. The results indicated that the addition of crumb rubber increased the optimum amount of binder in the mixture with 30% RAP.

Investigation on performance characteristics of dense graded hot mix asphalt with RAP and crumb rubber

The objective of this study was to fundamentally characterize the laboratory performance of traditional hot mix asphalt (HMA) mixtures incorporating high RAP content and waste tire crumb rubber through their fundamental engineering properties. The nominal maximum aggregates size was chosen for this research was 12mm (considering the limitation of aggregate size for surface layer) and both coarse and fine aggregates are commonly used in Italy that were examined and analyzed in this study. On the other hand, the RAP plays an important role in reducing production costs and enhancing the environmentally sustainable pavements instead of using virgin materials in HMA. Particularly, this study has aimed to use 30% of RAP content (25% fine aggregate RAP and 5% coarse aggregate RAP) and 1% of CR additives by the total weight of aggregates for mix design. The mixture of aggregates, RAP and CR were blended with different amount of unmodified binder through dry processes. Generally, the main purposes of this study were investigating on capability of using RAP and CR in dense graded HMA and comparing the performance of rejuvenator in RAP with CR. In addition, based on the engineering analyses during the study, we were able compare the fundamental Indirect Tensile Strength (ITS) value of dense graded HMA and also mechanical characteristics in terms of Indirect Tensile Stiffness Modulus (ITSM). In order to get an extended comparable data, four groups of different mixtures such as conventional mixture with only virgin aggregates (DV), mixture with RAP (DR), mixture with RAP and rejuvenator (DRR), and mixture with RAP, rejuvenator, CR (DRRCr) were investigated in this research experimentally. Finally, the results of those tests indicated that the mixtures with RAP and CR had the high stiffness and less thermal sensitivity, while the mixture with virgin aggregates only had very low values in comparison.

Geometrico-static modelling of continuum parallel robots

In this thesis, we explore three methods for the geometrico-static modelling of continuum parallel robots. Inspired by biological trunks, tentacles and snakes, continuum robot designs can reach confined spaces, manipulate objects in complex environments and conform to curvilinear paths in space. In addition, parallel continuum manipulators have the potential to inherit some of the compactness and compliance of continuum robots while retaining some of the precision, stability and strength of rigid-links parallel robots. Subsequently, the foundation of our work is performed on slender beam by applying the Cosserat rod theory, appropriate to model continuum robots. After that, three different approaches are developed on a case study of a planar parallel continuum robot constituted of two connected flexible links. We solve the forward and inverse geometrico-static problem namely by using (a) shooting methods to obtain a numerical solution, (b) an elliptic method to find a quasi-analytical solution, and (c) the Corde model to perform further model analysis. The performances of each of the studied methods are evaluated and their limits are highlighted. This thesis is divided as follows. Chapter one gives the introduction on the field of the continuum robotics and introduce the parallel continuum robots that is studied in this work. Chapter two describe the geometrico-static problem and gives the mathematical description of this problem. Chapter three explains the numerical approach with the shooting method and chapter four introduce the quasi-analytical solution. Then, Chapter five introduce the analytic method inspired by the Corde model and chapter six gives the conclusions of this work.

Influence of additives on the performance of a PVDF membrane

The field of use of membranes is wide and ranges from the automotive industry to biomedical uses. Many formulations and compositions find a niche where they are able to improve efficiency, running cost and quality of the product. The aim of this research is to expand GVS’s product portfolio introducing a new membrane formulation. A series of additives were researched and evaluated, adding them to the membrane solutions, which were then cast and characterised using techniques like Scanning Electron Microscopy (SEM), poroscopy, FT-IT ATR and measurements like Water Break Through (WBT), Air Flow (AF), thickness. This study ultimately focused on one additive, which effect on the membranes was studied in various compositions. Interesting insights were also collected on the stability of the polymer solutions over time, which was found to change the membrane properties significantly, mainly affecting airflow and water breakthrough. Properties of the membranes were studied to find possible correlations to the amount of additive. The additive seems however to change the membrane porometry considerably depending on the time of immersion in the water bath. A new procedure to yield uniform unsupported polymeric membranes for tensile tests was developed. The additive was found to reduce elongation at break and decrease tensile strength of the membranes, possibly hinting toward plasticization of the product.