Alternative Production Processes of Calcium Silicate Phases: A Review - Juniper publishers
Journal of Trends in Technical and Scientific Research
Abstract
Calcium silicates production by alternative methods
to solid state reaction method has gained importance because of the
possibility to obtain materials with higher performance and less energy
consumption than the traditional process. Exploring the application of
non-conventional methods for the production of cementitious materials is
an interesting alternative to produce materials with high performance,
as nanoparticles, which are expected to permit high reactivity of the
phases. The alternative methods require more studies allowing to
understand the individually and the combine effects of synthesis
processes conditions over the particles properties.
Keywords: Synthesis; Alternative methods; Calcium silicates; Clinker; Portland cement; Pure cement phases
Considerations
Global demand of cement is increasing year by year in
a factor of 25; therefore, greenhouse gas emissions from this industry
are growing in significant amounts. Nowadays, CO2 emissions
for cement production correspond almost to 5-8% worldwide, which is a
motivation to find solutions to reduce the environmental impact. Some
ways to attack this problem are applying new technologies, improving
current technology, and using alternative cement substitutes and
alternative fuels [1].
Ordinary Portland Cement (OPC) is a popular
construction material traditionally obtained by the combination of
limestone and clays. The main component formed during its fabrication is
the clinker, which is composed by four main phases, alite (Ca3SiO5 or C3S), belite (Ca2SiO4 or C2S), celite (Ca3Al2O6 or C3A) and ferrite (Ca4Al2Fe2O10 or C4AF).
The calcium silicate phases, alite and belite, are responsible of the
development of mechanical properties, such as compressive strength in
construction structures, while aluminate phases, celite and ferrite,
play a role in the setting time of cement and durability of concrete
[2,3].
Pure cement phases with nanometric size have been
obtained by non-conventional methods such as Pechini, sol-gel and self-
propagating combustion, which showed good results to the formation of
the cement matrix. The first work in the study of pure cement phases was
done by R. Roy and Oyefebesi in 1977 using the sol-gel method [4].
Since then, different research have been done in the study of the
process effects on the formation of cement polymorphs and their
reactivity, considering the anhydrous and hydrated compounds [5-12].
The study of cementitious materials, such as pure
cement phases, allows the understanding of phenomena related to
hydration chemical reactions of clinker, enabling the improvement of
cement properties in macroscopic systems and providing more information
about the influence of atomic position on the level of reactivity of the
structure in single crystal systems [3,13].
Production and performance improvements of
cementitious materials allow the reduction of energy consumption and
mitigate the negative impacts of cement industry. Most strategies are
focus on the improvement of clinker performance and alternative
processes for its production. Hence, this paper shows a review of
research focused on the synthesis of cementitious phases, especially the
calcium silicates alite and belite, through non- conventional methods.
Polymorphs of calcium silicate phases and their
hydration activity are a broad topic that is strongly studied around the
world. The wide amounts of variables make of this topic a complex
research, which is why there is not a single answer to the phenomena
that occurs in cement phases formation and hydration.
The use of alternative synthesis methods with control
over the process conditions in the production of cementitious phases
allows manipulation of products features, and therefore a better
understanding of the crystal structure of the cement phases and the
hydration mechanism to improve the properties of the cement [14].
Alternative synthesis methods as Pechini, sol-gel and
selfcombustion are become important because of the possibility of
reducing the energetic consumption process and produce nanoparticles
with superior features than traditional powders. However, all of them
are batch methods, which is a limitation to scale-up the process.
Therefore, it is important the implementation of continuous methods
which allows the scale-up of the process.
To Know More About Trends in Technical and ScientificResearch click on: https://juniperpublishers.com/ttsr/index.php
To Know More About Open Access Journals Please click on:
Comments
Post a Comment