Assessment of construction and demolition waste materials for sublayers of low traffic rural roads

The need for exploiting massive amounts of natural raw materials for constructing pavements of roads as a key element for development of infrastructures in modern age, together with enormous production amounts of wastes related to civil engineering activities as biggest portion of solid waste generated all over the world, have highlighted the importance of utilizing recycled aggregates of these materials in road pavement layers. The key factor in this quest, is to evaluate load-bearing abilities of various kinds of waste aggregates. Aggregates of reclaimed asphalt, pre-stressed or normal concrete, masonry and demolition waste (CDW) exhibit different behavior under loading after compaction. The ideal situation would be to achieve the densest compacted and durable layer in order to get the highest durability, comparing to traditional road materials. In this study, aggregates from four types of recycled materials are being subjected to study for unbound and cemented pavement layers. Initial laboratory evaluations of size and composition are followed by constructing a field on a subgrade with high non-homogenous surface. Vibrating elastic modulus (Evib) for these materials were determined by Continuous Compaction Control (CCC) Oscillating Rollers. It is observed that, despite the weaknesses arisen from weak components such as masonry and elongated tiles, the stabilized distribution of the particle size can accelerate reaching to final compaction of unbound aggregates with roller passing. This process could be repeated with more or less same pattern in cemented layer, which exhibited an enhanced stiffness and uniformity in order to minimize the weak parts of non-uniform subgrade layer, and provide a high rigid pavement

Design of Hybrid Solar Cell Based on Dye-Sensitized TiO2TiO_2 Nanoparticles with Conjugated Polymer

In this paper, we have proposed dye-sensitized hybrid solar cell based on $TiO_2$ nanoparticles as a medium for electron transport and conjugated polymers as hole-conductor, where dye molecules absorb solar radiation and create electron-hole pairs. This solar cell can be a better alternative to conventional electrolyte based dye-sensitized solar cells, because of enhanced characteristics of performance. We have simulated it numerically, to study essential characteristics of the structure such as electron, hole and their current densities and internal electric field in two operating conditions of open-circuit and short-circuit cases. Then current-voltage characteristic diagram has been plotted and energy conversion efficiency calculated

Using recycled aggregates from construction and demolition waste in unbound layers of pavements

Pavements are an expensive part of transportation infrastructures, as their construction and maintenance require large amounts of resources and materials every year and all over the world. A sustainable solution for considering environmental concerns about roads and pavements, in general, is utilizing recycled materials for their construction. This has been shown to lower the carbon footprint of the construction sector and to result in natural resource conservation, in reduction of harmful emissions and in minimization of overall costs for pavement construction and maintenance. One of the main groups of recycled materials which has attracted much attention since the end of the last century is construction and demolition waste aggregates (CDW). This paper reviews the completed studies referring to the use of the construction and demolition waste aggregates in unbound layers of pavements and compare the in-hand results from various engineering assessments of these aggregates and mixes. A number of tests and evaluations are applied in order to enhance the required quality and durability of the pavements under given traffic volumes traffic loads and climate actions. Today, unbound recycled aggregates (RA) are mainly used in the lower layers, such as subgrade, capping, sub-base and base, but in rural roads they can be adopted also for bound layers, towards the surface of the structure and may be constituents of bound layers and of novel surfacing applications