Scientists from the Research Group of Chemical and Environmental
Engineering at the University of Jaén (UJA) have manufactured bricks
composed mainly of olive and pine pruning ashes which have a higher
porosity and lower thermal conductivity compared to traditional clay.
Highlights of the Research Paper
A way for recycling fly and bottom pine-olive pruning ash as raw materials in clay bricks is shown.
The best results are obtained with the incorporation of 20 wt% of bottom biomass ash fired at 1000 °C.
Bottom and fly biomass ash improved the thermal conductivity.
Mechanical properties of ash-bricks met the UNE standards.
Abstract
The present study investigates the feasibility of using fly or bottom
biomass ash as a partial replacement in the production of eco-friendly
construction materials.
The fly and bottom ashes from combustion of
biomass (olive pruning and pine pruning) generated in a Spanish Power
Plant were used as raw materials to replace clay for the production of
fired bricks. First, the mineralogical and chemical composition and
thermal behavior of the ashes and clay were determined. Next, ceramic
bricks were manufactured by compressing clay and different quantities of
fly or bottom biomass (0–30 wt%). Different firing temperatures, 900
and 1000 °C, were studied.
The effect of adding fly or bottom biomass
ash on the technological behavior of the brick was assessed by studying
linear shrinkage, water absorption, bulk density, compressive strength,
thermal conductivity and the morphology.
The results have shown that the
optimum sintering temperature was 1000 °C. The increase in the firing
temperature from 900 to 1000 °C, raised the compressive strength and
decreased the water absorption. The addition of 30 wt% of bottom or fly
biomass ash produced bricks with very high water absorption values and
low mechanical properties.
Based on the results obtained, the optimum
amounts of bottom or fly ash were 20 wt%. These percentages produced
bricks whose mechanical properties were suitable and thermal
conductivity decreased by 21% respect to the standard bricks. The
addition of bottom biomass ash produced bricks with slightly better
properties, due to the most appropriate composition of these ashes.
The
bricks do not present environmental problems according to the leaching
study. Therefore, fly and bottom biomass ash from the combustion of
olive-pine pruning could be used as secondary raw materials in ceramic
brick production.
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Source: D. Eliche-Quesada et al (October, 2016). Investigation
of using bottom or fly pine-olive pruning ash to produce environmental
friendly ceramic materials. Department of Chemical, Environmental, and
Materials Engineering, Higher Polytechnic School of Jaén, University of
Jaen, Spain