http://www.decodedscience.com/bioglycerol-use-construction-industry/53790
Bioglycerol and Its Use in the Construction Industry
April 17, 2015 by Clara Piccirillo, PhD
Bioglycerol, or crude glycerol, is impure glycerol obtained as a
by-product in the biodiesel industry. Researchers now show that it is
possible to employ bioglycerol as a multipurpose grinding additive for
the manufacture of cement, with better performance than pure glycerol.
Cements with bioglycerol are produced with lower energy consumption and
the finished concrete structures have significantly better mechanical
properties and corrosion resistance.
How will this new discovery impact the environment – and the
construction industry?
The Impact on the Environment of the Construction Industry
The construction industry has a huge impact on the environment.
Considering the use of natural resources, for instance, data indicate
that almost a quarter of the raw materials extracted from the
lithosphere are employed in construction.
The manufacture of cement is one of the most environmentally impacting
of mankind’s activities. The cement fabrication process requires heating
the cement components (i.e. limestone, clay, sand, etc.) at no less than
1600 oC for the “clinker” mixture to be formed. Further energy is then
required to grind the clinker into a fine powder, and for the cooling
process. Overall, the calcination and grinding processes account for 80%
of energy consumption, while power for the cooler accounts for the
remaining 20%.
Reducing Construction’s Impact
To try to reduce the construction industry’s impact on the environment,
researchers have been trying to modify the fabrication process; the
challenge is to make the process more sustainable without compromising
the quality of the cements. This is especially important for higher
grade cements used for advanced construction.
A way to obtain good quality cement using less energy is the use of
grinding additives; these are generally organic molecules which favor
the grinding process – i.e. the formation of small micrometric particles
from the clinker. This, in turn, leads to a decrease in the energy
required in the process.
Examples of Cement Grinding Additives (CGAs) include triethanolamine,
diethylene glycol and glycerol.
What is Bioglycerol?
Glycerol is a polyalcohol – you can see its formula in the figure on the
side. Scientists are well aware of its potential as a CGA. However,
using glycerol in the concrete construction industry has historically
been restricted due to the high price of the pure substance.
In 2005, however, some Italians researchers had the idea to use
bioglycerol, or crude glycerol, and could see the potential of this
approach. Both ‘bioglycerol’ and ‘crude glycerol’ are terms that refer
to glycerol obtained as a by-product of biodiesel production.
Now some scientists from National Research Council of Palermo (Italy),
who were involved in the early work on bioglycerol, published a review
paper on this topic. Their research was conducted in cooperation with
the Universities of Milan (Italy) and Panama. They published their
research in Biofuel, Bioproducts and Biorefining in April 2015.
Bioglycerol: An Excellent Grinder
Decoded Science spoke to professor Mario Pagliaro, leading scientist in
the study. Dr. Pagliaro tells us:
“Bioglycerol is a most valuable compound for the concrete construction
industry, exactly for the same reason which makes it unusable in
pharmaceutical or personal care applications, namely that it is not pure.
Residues of soap as well as of α-tocopherol from the biodiesel
production, lead to excellent mechanical, anticorrosive properties and
to better performance as a CGA than both pure glycerol and oil-derived
additives. Reduction in power consumption in the grinding process is up
to 10% when compared to oil-derived additives, while concrete finished
structures are more than 10% stronger than identical structures obtained
with no added bioglycerol.
Finally, the stability of the antioxidant polyphenol contained in brown
bioglycerol ensures prolonged anticorrosive properties.
These are properties which can have a huge impact if considered on new
huge concrete structures, such as the enlarged Panama’s Channel, dams,
bridges, airport pavements and highways.”
Bioglycerol’s Other Qualities
Bioglycerol addition also decreases the adhesion of the cements to molds
and forms; this means that it is easier to remove the cured cement from
the molds frequently employed during construction, without creating
surface imperfections. Conventionally, construction companies use highly
polluting spent diesel fuel or spent mineral oils as form releasing
agents, a practice that has recently been forbidden in the US leading to
the introduction of much more expensive lubricant formulations.
Crude Glycerol Has Great Potential
“These data clearly show the potential of bioglycerol as a
multifunctional cement additive.” Dr Pagliaro told Decoded Science, “Its
use improves the quality of the final products, but also the overall
sustainability of the concrete construction business; in fact, with
bioglycerol, we do not use an oil-derived chemical, but a renewable
oleochemical obtained from processing biomass.
Since its first use as a CGA in Italy about ten years ago, construction
companies have been using bioglycerol at increasing pace; in 2010, for
instance, bioglycerol accounted for 20% of the grinding additives in the
European market.
As a trend for the future, we expect bioglycerol to find widespread
application. Indeed, ever more data published by different researchers
in different countries confirm its suitability for the manufacture of
superior cements. Moreover, the biodiesel and oleochemicals industries
are growing in scale all over the world, which means that we will have
enough amounts of cheap bioglycerol available for satisfying this and
other applications of this great platform biochemical.”
Bioglycerol: Making the Construction Industry More Sustainable
As the impact on the environment of the construction activities is
huge, it is important to make this industry more sustainable. The use of
bioglycerol, a by-product from the diesel production, is surely a step
in the right direction, as it reduces the dependance on oil-derived
chemicals. Moreover, the process requires less energy and gives
materials with better properties.
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