Javier Ordóñez

Use of Recycled Construction and Demolition Waste Aggregate for Road Course Surfacing

The need to manage construction and demolition waste (CDW) has led to environmentally-friendly actions that promote the reuse and recycling of this type of waste and other forms of waste valorization. The main priority is to foment sustainable construction work, which has the advantage of avoiding the deposit of large quantities of construction waste at landfills and greatly reducing the use of borrow material in construction projects. In this sense, the reuse of CDW materials significantly lessens the impact of construction work on the surrounding environment. The aim of this research study is to verify the technical viability of using construction waste as material for the base pavement layers of road surfaces. For this purpose, a field study was carried out, which included testing the performance of pavement composed of concrete, asphalt mix, and ceramic waste aggregate. This was done by analyzing the characteristics of the recycled material on a section of an actual road under real vehicle traffic conditions. It was observed that the load-bearing capacity of the recycled artificial CDW aggregate was satisfactory.

Improvement of Bearing Capacity in Recycled Aggregates Suitable for Use as Unbound Road Sub-Base

Recycled concrete aggregates and mixed recycled aggregates are specified as types of aggregates with lower densities, higher water absorption capacities, and lower mechanical strength than natural aggregates. In this paper, the mechanical behaviour and microstructural properties of natural aggregates, recycled concrete aggregates and mixed recycled aggregates were compared. Different specimens of unbound recycled mixtures demonstrated increased resistance properties. The formation of new cement hydrated particles was observed, and pozzolanic reactions were discovered by electronon microscopy in these novel materials. The properties of recycled concrete aggregates and mixed recycled aggregates suggest that these recycled materials can be used in unbound road layers to improve their mechanical behaviour in the long term.

Dual-stage peat beds in small community wastewater treatment

In this study, the quality of water treated by two dual-stage peat bed systems was compared with a single-stage system, and a costs analysis was performed. The experiment was carried out on a pilot scale using pre-treated urban wastewater. The pilot setup consisted of a single-stage system with a hydraulic loading of 0.6 m3/m2d, and two dual-stage systems. The first of these worked with hydraulic loadings of 1.2 and 0.6 m3/m2d for the initial and second stages respectively. For the second dual-stage system hydraulic loadings were 1.8 and 0.9 m3/m2d. In comparison with the single-stage system, the dual-stage systems produced effluents with a substantial improvement in physicochemical quality (suspended solids, COD and BOD) and microbiological quality (faecal and total coliforms). Quality parameters were similar to a conventional system, meeting the legislative standards of European Union Directive 271/91 for wastewater treatment. Total costs of the peat-bed systems showed a reciprocal X-model regression depending on the average daily volume of urban wastewater to be treated, with a tendency towards convergence of costs between the single and dual-stage systems. The main problem with the dual-stage systems is the greater surface area required for their installation, which can be estimated by linear regression depending on the average volume of water to be treated per day.