Expanded clay helps to improve the environmental footprint of mortar

Mette  Glavind

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Expanded clay helps to improve the environmental footprint of mortar

Maxit Group case story for Teknologisk Institut website

In 2008 the DTI Concrete Centre assisted the international producer of building materials maxit Group with CO2 calculations to assess the effect of expanded clay aggregates in premixed masonry mortar. These types of mortars are typically produced in 25 kg bags for building sites and the DIY market but can also be delivered in silos.

By substitution of natural sand with crushed expanded clay aggregates the weight of one premix bag may be halved, which again have large impact on both handling and application of these products. The amount of mortar coming out of a premix bag is not altered it is simply a lighter product.

The work was requested by Kim Rosenbom, responsible for the Commercial Development of Expanded clay in maxit Group (now a part of Saint Gobain Weber). “We had a feeling that lightweight products would be much more environmentally friendly than the normal weight products but many people questioned our “feelings” due to the energy intensive production process of expanded clay”. Kim Rosenbom continues “the DTI performed calculations that showed how lightweight products really have a benefit when transportation is considered correctly and when looking at the whole life circle of the product”.

The CO2 calculations were performed based on the newest inventory data from Danish expanded clay production. They showed that the CO2 footprint at the mortar factory gate is almost identical for normal and lightweight mortar. However, the CO2 emissions during transportation to the building site are significantly different in favour of lightweight mortar.

“We are now trying to combine these new environmental data with investigations of the impact of lightweight mortar on the working environment for masons. It is no secret that masons are subject to some of the harshest working conditions and we would like to take some of the load of their backs” says Kim Rosenbom. “Each square metre of normal brick masonry means almost 40 kg less building materials to be handled by the workers. This really sums up to a significant load during a lifelong career as mason” he finishes.