Civil Engineering Reference
In-Depth Information
2012), natural pozzolans from the island of Milos in Greece (Velosa and
cachim, 2009), and volcanic ash from Rabaul in the Papua new Guinean
province of East New Britain, where the source was a volcano known as
Mount Tavurvur (Hossain, 2005). Such papers attest to the topicality of
research on natural pozzolans.
Nonetheless, the difficulties in exploiting natural pozzolan quarries
continue to grow, primarily due to concerns around their impact on the
landscape. alternative materials must therefore be sought. Furthermore, the
Kyoto protocol has established demanding reduction targets for greenhouse
gas emissions, while the use of eco-friendly materials has been driven by
the growing awareness of the contribution of energy consumption to global
warming and climate change. These materials may be industrial by-products,
as explained in Chapter 5, or materials which, while not active in their
original natural state, have undergone industrial processing that affords them
pozzolanic characteristics. This is the case of the waste generated by the
fired clay industry.
The inclusion of ceramic waste in Chapter 4 on natural pozzolans rather
than in Chapter 5 on artificial pozzolans is justified by the origin of the
material. Ceramic waste comes from calcined natural clay. While this thermal
treatment is the result of a manufacturing process, it nonetheless constitutes
thermal activation. as a result, if these materials were included in a possible
future standard, they would be regarded as natural calcined pozzolans (Q),
further to the definition of that material in European Standard (EN 197-1,
2011), natural calcined pozzolans are materials of volcanic origin, clay,
shales or sedimentary rocks active by thermal treatment.
Thirty million tonnes of fired clay products such as bricks, roof tiles and
block were manufactured in Spain in 2006, although with the economic
crisis, this figure has since tumbled to ten million tonnes (Hispalyt, 2011).
nonetheless, the percentage of discards continues to make this material
attractive for use in construction, as a source of pozzolan for cement
production. In addition, according to the national construction and demolition
Waste Plan (Official State Journal, 2009), 54% of the 40 million tonnes of
construction and demolition waste produced annually in Spain comprise
fired clay materials, which are presently being studied for their aptitude for
the above purpose
1
.
While the polluting power of this inert waste is low, it poses a severe
environmental problem because it must be stockpiled, a practice that mars
the landscape. during the manufacture of brick and similar products, which
involves dehydration followed by firing at controlled temperatures ranging
1
Sánchez de Rojas M.I., Head researcher for research project BIA 2010-21194-C03-01,
funded by the National Plan for Scientific Research, Development and Technological
Innovation. Ministry of Science and Innovation.
