Cement and concrete within the framework of the circular economy
The circular economy concept applied to the cement and concrete industry supposes the indefi nite reutilization of the cement and cement-based products. This paper presents the approach of the Spanish and European cement producers to change the linear economical model, which was followed from the industrialization period, towards a circular approach. This fact would increase the use of industrial by-products as raw materials or alternative fuels in the manufacture of portland cement clinker, or as a portland cement constituent. Also, concrete recycling would be promoted.
Circular economy with regard to the future cement standards
Cement standardization when industrial by-products are used is a strategic need of the countries because it can promote the development and the consolidation of the cement production sector in the developed countries. Therefore, circular economy concept in such sector means the endless reutilization of the cement and cement-based materials together with the attainment of more durable structures. This paper presents the European trend with regard to the utilization of industrial by-products as portland cements.
Economic and environmental limitations of recycled concrete use
Several studies have proved the technical feasibility of concrete and mixed recycled aggregates in concrete production. However, recycled aggregate has worse properties than natural aggregate, with a subsequent decrease of strength and other concrete properties, requiring, in many cases, a reduction of the water/cement ratio to compensate the effect. This may lead to an increase of concrete price.
The present study evaluates the effect produced by different parameters such as the type and percentage of recycled aggregate and the concrete strength class on concrete production, considering economic and environmental criteria, enabling to select their optimal applications of recycled aggregate from this point of view.
Thermal structural concrete. Circular economy
The use of a thermal structural concrete in construction (buildings and works) makes concrete in a modern, efficient and sustainable material, contributing to the circular economy, by thermal activation of building structures and energy rehabilitation of buildings. The thermal activation of the structure of buildings and coupling it with thermal storage system as the ground (geothermal energy), is considered as the most effective and sustainable method for climatisation of buildings, being recommended building policy consumer almost zero or Passivahus system.
This activation is performed by introducing tubes in concrete structures, and is highly favored by the thermal inertia thereof and ground. The thermal structural concrete, thanks to their improved thermal conductivity, significantly increases this inertia. Therefore, the thermal structural concrete allows heat utilization constructions, connecting the geothermal block structure and obtaining an efficient and sustainable climatisation.
Circular economy integration in infrastructures sustainability
The circular economy is a growing trend, although there will be planned from early stages in the form of work in the construction sector, since the atomization of it and disaggregated existing approaches are a difficulty great practice barrier. Of the different agents involved in the construction, the contractor may have different circumstances of performance depending on the country.
This article first reflects on the overall context for showing, subsequently, an illustrative example of circular economy with the introduction of innovative alternative. The example shows the use of self-compacting concrete arises with fibers and mixed recycled in 100% substitution of coarse aggregate for CPI-8 piles.
Assessment of construction and demolition waste management in Spain in the field of circular economy
In the present research work is evaluated the management of construction and demolition waste (C&DW) in Spain. The objective is identifying the strengths and weakness of the sector nowadays. This management is carried out in recycling plants distributed throughout Spanish geography, and the main motivation of the study lies on the high production of C&DW. This kind of waste is a major problem in modern society, as it accounts for 25–30% of all the solid waste generated yearly.
Recycling of roads. An economic and circular solution
More and more products are recycled every day, but does the society really know that roads are fully recyclable? A modern society demands a circular economy and technicians must consider recycling these pathways as the greatest quarry that a country can have as a source of supply of aggregates.
Cold in place recycling with cement allows a total recovery of the pavement. An homogeneous layer of high structural capacity is achieved with this solution. It can be used in many pavements as industrial estates, ports, airports, etc. This is not a new solution, but it is an innovation fi eld with more than 25 years experience in Spain, where about 28 million square meters have been recycled.
There are many advantages of recycling pavement with cement, both technical and economical and especially environmental. This article describes the research process and calculations made at the University, as well as a catalogue of recycled pavement sections is proposed.
Circular economy on precast concrete industry: towards the challenge of “zero waste”
Action Plan on circular economy approved by the European Commission sets to carry out such enhanced use of resources, reducing those consumed and reintroducing them into a new production cycle. Precast concrete as industrialized version of construction concrete off ers such a good package of characteristics to ensure a best adaptation to upcoming requirements, as less produced waste an if generates, are in the factory itself in which a best process; durability to longer the lifetime of a building; or an optimized structural design. This article is addressed to show a global view of technological situation of precast concrete industry according to this trend and review some recent or future experiences that will serve to satisfy the goals to be set by this sustainable approach.
Works with recycled aggregates from construction and demolition waste
Circular economy incorporates recycled aggregates and other recycled materials from construction and demolition into production processes. After be recycled, these waste pass to be raw materials giving place to new products that meet the technical requirements for some applications and have the CE marking.
In Spain this is not new because since more than fifteen years, these recycled aggregates are used for several applications such as mortars, green roofs, concrete mass and structural and as raw material in cement production process. A good example of this applications is the publication of the “Spanish guide of recycled aggregates” in which there are more than 100 works documented from 2008 to 2010.