plenary – WASCON 2015

Low CO2 cement from waste

Wascon 2015 — Fri, 15 May 2015 15:54:31 +0000

Of global Gross Domestic Product (GDP), 10% is contributed by the construction industry, which is worth annually about USD 8 trillion. With world annual cement production exceeding 4 billion tonnes and contributing 5 to 8% of global CO₂ emissions, there is ample motivation to reduce this figure, partly by using reactive waste. The cement industry has been utilising waste such as coal fly ash and blast furnace slag for many years by blending with Portland cement, hence reducing CO₂ emissions by about 30%. In order to reduce such emissions significantly, a shift in binder chemistry is required. Alkali-activated cement (AAC) made from fly ash, metallurgical slags and natural pozzolans could reduce CO₂ emissions by at least 80% compared with blended Portland cement (PC).

Although the valorisation of waste utilising AAC technology creates a new value chain, there are substantial barriers to the commercial adoption of AAC, or any alternative binder system. All concrete standards are based on the implicit assumption that PC is the main binder, while some standards like the European standards specify a minimum PC content. Therefore, if no or little PC is used the concrete does not comply with the standards, hence few design engineers and asset owners are prepared to accept the risk. In the absence of a long in-service track record, research is required to validate durability testing methods and improve AAC technology. Even when asset owners and accept the results of durability testing of AAC, a key barrier to entry into an established market is access to a suitable supply of source materials. High profile projects in Australia have demonstrated the vast regulatory, asset management, liability and industry stakeholder engagement process required to commercialise AAC.

La entrada Low CO2 cement from waste aparece primero en WASCON 2015.

End-of-Waste Criteria

Wascon 2015 — Thu, 14 May 2015 16:16:02 +0000

The Waste Framework Directive 2008/98/EC introduced the concept of end-of-waste criteria, with the aim of supporting recycling markets in the EU by creating a level playing field and increasing legal certainty for all actors in the sector. According to Article 6 of this Directive, a waste substance or object may cease to be waste and be traded freely as a product when it has undergone a recovery, including recycling, operation and it meets a number of criteria. These criteria define the proper use and market conditions for the material and ensure that its use under the product regime will not lead to overall adverse environmental or human health impacts.

Today, EU Regulations with end-of-waste criteria already exist for aluminium, iron & steel and copper scrap, as well as for glass cullet. Technical proposals have been developed by the European Commission for paper waste, biodegradable waste and waste plastics. In addition, studies were published on the impacts on the recycling markets from the first end-of-waste Regulation and on a methodology for setting pollutant limit values for aggregates derived from waste for use in a possible end-of-waste framework. The latter study focuses primarily on environmental risks and limit values associated with leaching of substances from aggregates.

This presentation will give a general overview of the end-of-waste work realized at EU level to date, before discussing the aggregate study in more detail.

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Durability and Sustainability of recycled waste materials in construction

Wascon 2015 — Wed, 13 May 2015 16:17:00 +0000

As it had been demonstrated for more than a half of a century, construction and demolition waste, steel slag, other industrial and domestic wastes or by-products, have a potential for being transformed in construction materials. Not only concrete, bituminous mixtures or granular materials for roads have been considered, but new products have been developed to extend his field of application. Researchers have very often concentrate his efforts in recycling this transformed waste materials, but they subsiste several questions about the durability under different environments and in particular about his real sustainability. The consideration of the high contents in cement used in some recycled concretes, can be a good example to discuss about his sustainability. Durability problems have to be considered in the specific environment, as leaching have to be. We have to adress the obtention of recycled materials from environmental perspective, and durability is an environmental concept, some times more complex that we can deduce considering only the general specifications.

La entrada Durability and Sustainability of recycled waste materials in construction aparece primero en WASCON 2015.

Using Industrial Symbiosis as a tool address Resource Criticality: a UK Construction Sector Perspective

Wascon 2015 — Tue, 12 May 2015 16:17:59 +0000

Using Industrial Symbiosis as a tool address Resource Criticality: a UK Construction Sector Perspective

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