Lightweight concrete using fly ash aggregate
Amongst the
most important methods regarding global manufacturing nowadays is solid waste management.
The study in this article looks towards utilizing waste as efficiently as
possible, and at the same time turning it into some kind of a business. In this
case, the utilization was done for constructive purposes, to make eco-friendly
materials, in order to sustain the globe for a longer period of time.
There are
countless studies and projects about this matter, but this particular one concentrates
on how to utilize fly ash aggregate in concrete. During the project, the researchers
made a survey, and from the results it can be seen that the fine coarse
aggregate was completely replaced by the fly ash aggregate.
The
researchers used ordinary Portland cement in the tests where the fly ash
aggregates were mixed with cement and water. Mixing a test batch allowed
studying and researching the chemical and physical properties of the fly ash
concrete. Fly ash concretes’ crushing value and impact value were tested and
compared to the traditional concrete.
Mixing
proportions of the cement and fly ash were 15:85, 20:80 and 25:75, and the
water content was 20 % of the total weight. With these proportions, a series of
test blocks was casted, including concrete cubes, concrete cylinders and
concrete beams. Also, compressive strength, split tensile strength and flexural
strength of the fly ash aggregate concrete, on the different points of its life
cycle, were tested. All in all, it can be concluded that in the future, fly ash
aggregate has potential to evolve into the building material of tomorrow.
Conversion
of fly ash into zeolite, to decontaminate water
Zeolite is an adsorbent material, obtained while
adding sodium hydroxide to fly ash samples. The different composites already
present in the fly ash, aluminium and silicon, mixed with sodium hydroxide are
able to form zeolite by mechanic agitation.
Zeolite can be used to remove contaminants
like heavy metals from water. Heavy metals like cadmium are present in the
aquatic environment, and it has become important to remove them due to their
toxicity and non-biodegradability. Moreover, cadmium can damage the kidneys and
the livers of animals, and human body doesn’t have the homeostatic control for
the metal.
Thanks to this study, it has been shown
that the use of zeolite is an efficient option to decontaminate water, and also
a low-cost option compared to other ones. Sure thing is, synthesized zeolite
has a better adsorption capacity than original fly ash and natural zeolite.
Achieving
sustainability with lightweight aggregates
Lightweight aggregates can be considered as
a more environmental-friendly option than the normal weight ones. Proven
benefits are at least the 20-30% reduction in density, and up to 50% reduction in
heat conductivity.
In construction, several studies have shown
that for example the bridges built of lightweight aggregate materials have been
as durable as the ones built of normal weight materials. Thinking about the
sustainability part, these aggregates can be helpful in order to reduce the
“heat island effect”. For instance, tar and gravel roofs are being replaced by
greener solutions, and lightweight aggregates offer one option for the process.
Also, the production of lightweight
aggregates tenders a way for sustainable disposing of hazardous waste. In
addition, the surfaces of these kind of aggregates create a great base for the
development of bacterial growth in municipal waste treatment, or in urban
areas’ drainage flows.
Sources:
Rama Prasad, C.V.Siva. (2017) Light Weight Concrete using FlyAsh Aggregate. https://www.researchgate.net/publication/322050386_Light_Weight_Concrete_using_FlyAsh_Aggregate
Das, G; Pradhan, N.C; Madhu, G.M & Preetham,
H.S. (2012) Removal of Cadmium from Aqueous
Streams by Zeolite Synthesized from Fly Ash. http://www.jmaterenvironsci.com/Document/vol4/vol4_N3/51-JMES-352-2013-Gaurav.pdf
Remner, T.W; Ries, J.P & Wolfe, W.H. (2007)
Achieving sustainability with
lightweight aggregates. http://www.claisse.info/special%20papers/bremner_full_text.pdf
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