QUARRY AND AGGREGATES
Panoramic of the construction and demolition waste management in Spain and Europe. Realities and myths of the recycled aggregates
In the framework of circular economy, construction and demolition waste (CDW) represent one of the largest volumes. In addition to the recovery of other products (wood, metal, plastics, etc.), a good management of the CDW from the demolition (or even earlier in the product ecodesign and the construction of works) is a prerequisite to obtain recycled aggregates that comply with the regulations applicable to these products. While in Spain, the situation is still far from being the most suitable, the aggregates sector is called -as it happens in other European countries where recycling is today a reality- to be a major player in the process of recovery of the CDW.
Use of photocatalytic cements on urban roads with high traffic volumes
Among the different photocatalytic solutions available on the market, i.active® cements by Italcementi Group are the most common raw materials currently utilized for the manufacturing of building products possessing an added value in terms of sustainability and durability.
One of the main purposes for their use is to reduce pollution, in order to improve the air quality in urban environments. Another environmental advantage in their use is in terms of mitigation of urban heat island effects.
Currently, i.active® cements are commercially available in Europe, North America, North Africa and India. Several million square meters of photocatalytic cement-based surfaces, have already been applied, and this number is expected to grow substantially in the coming years.
In this framework, photocatalytic cementitious roads and pavements represent the widest application for the improvement of air quality in urban environment.
This paper gives an overview of the product performances to help engineers to choose and design sustainable and durable paved surfaces that typically represent from 30% to 60% of developed urban areas.
Reduction of the calcium leaching rate of cement paste by addition of silica nanoparticles
Calcium leaching is a degradation process that consists in the progressive dissolution of the cement paste as a consequence of the migration of the calcium ions to the aggressive solution. Although it is a well-known phenomenon, a way of reducing it has not been found yet. The aim of this work is to prove how the addition of small amounts of silica nanoparticles to the cement paste can induce such reduction. The experimental results obtained have shown that nanosilica increases the strength of the cement paste about a 30% in cured samples and more than a 100% in the asymptotically leached ones. At the level of the structure of the C–S–H gel, silica nanoparticles increase the average length of the silicate chains and reduce their polymerization as calcium dissolves. An important decrease of the degradation in terms of porosity and amount of calcium lost has also been observed.
EQUIPMENT PROVIDERS 1
Calcium Nitrate as admixture for concrete brick production
This paper wants to stimulate knowledge transfer from ready mix concrete to concrete brick and element production. The production of concrete elements and bricks needs to be sustainable and cost efficient, and admixtures can help to reach this objectives. Especially partial replacement of steam curing by use of admixtures can be interesting, too. A potential candidate for such an admixture is Calcium Nitrate that is today mostly used as stand-alone admixture or part of formulations in ready mix concrete.
EQUIPMENT PROVIDERS 2
FLSmidth with local cement industry
New FLSmidth maintenance Symposium with high cement plants participation. More than 70 people from more than 40 cement plants from Spain and Portugal joined the second edition of the FLSmidth Maintenance Symposiums. Subjects as: kiln axis, live ring and shells surfaces, kiln seals, crack repairs, inspec tions, etc., were dealt deeply and a lot of questions were solved on the way.
EQUIPMENT PROVIDERS 3
Cement 4.0, the way to efficiency
The authors describe their philosophy about the idea of Cement 4.0 the way to effi ciency by means of using new technologies and solutions as the “High Pressure Gunning Method” or implementing the latest solutions for costs reducing and energy efficiency through the “smart factory” concept.
A (r)evolution called BIM
Increasing introduction of BIM methodology within the projects is such an excellent opportunity to precast concrete industry as a way to its definitive consolidation. Both BIM and precast concrete are based on similar parameters: more control, quality, lower lifetime costs and, therefore, more efficiency. BIM is changing the way of work as it shows the Spanish Ministry of Development which has affi xed the end of 2018 to make all the public project under BIM. In order to meet with this scenario, ANDECE has developed a technical BIM library of representative precast concrete products to introduce this new methodology into the industry.
Sika solutions for recurrent problem of low concrete cover in reinforced concrete structures
The problem of low cover to reinforcement bars in concrete can be solved by adding additional mortar or concrete to the external surface (Principle 7 method 7.1 of European Standard EN 1504-9), or by applying protective coatings (Principle 1 method 1.1 and 1.3 of European Standard EN 1504-9) or intumescent coatings. This technical paper discusses the various Sika solutions and levels of protection which can be applied to protect concrete.
Restoration of ‘Charco del Tamujo’ gravel pit: Integration of wetland biodiversity concept into the restoring process of a gravel excavation site
The gravel pit ‘Charco del Tamujo’ is located in the municipality of Fuente El Fresno (Ciudad Real) and located between the National Parks ‘Cabañeros’ and ‘Las Tablas de Daimiel‘, and the edge of the Biosphere Reserve ‘Mancha Húmeda’.
In this context, and with the ongoing commitment of Lafarge-Holcim for biodiversity, a restoration actions have been designed and implemented, aimed at recreating a unique space: a wetland that enhances the development of local flora and fauna of high ecological value.
The result is an area with great potential for public uses such as nature tourism, research and opportunities for conservation.
Self-compacting concrete in the rehabilitation of the bridge on the river Palancia (Castellón)
The use of self-compacting concrete is particularly suitable for very reinforced structures and/or difficult to vibrate. This is the case of the rehabilitation of the bridge over the river Palancia, in Castellón.