89
STANDARDS ON THE BLENDED CEMENTS
Geun-Seong LEE, Zebo BABAKANOVA and Mastura ARIPOVA
Dept. “Technology of Silicate Materials, Rare and Precious Metals”
Tashkent Institute of Chemical Technology, Tashkent, Uzbekistan
Abstract
The cement industry is currently making various efforts to reduce CO
2
emissions. The blended
cement produced by lowering the amount of clinker with using mineral additives has expanded as
the trials to reduce CO
2
emission as well as to utilize its advantageous properties. And standards
related to blended cement have been already set in all regions of the world. It is evaluated and
reviewed the standards of blended cement according to the types and usage ratios of mineral
additives that can be blended, which are covered by the European Standard (EN 197-1:2011), the
Euro-Asian Standard (ГОСТ 31108-2020) and the U.S. Standard (ASTM C 595-16), respectively.
In accordance with the blended cement standard established in each region, it is necessary to
promote and expand the use of blended cement to reduce the CO
2
emission currently facing as well
as to utilize various advantages of using blended cement.
Global warming and climate change due to the CO
2
emission are currently one of the most
important issues in the world. In the cement manufacturing process, the CO
2
emission comes
mainly from two parts: the raw materials and the fuel burning. Thus, nowadays, the cement industry
is facing challenges to reduce CO
2
emissions. The production of cement is still responsible for
about 5-8% of global total CO
2
emission. The main approaches to reduce CO
2
emissions in the
production of Portland cement are: (i) increasing energy efficiency in the production process, (ii)
use of alternative fuels to reduce fossil fuel combustion, (iii) replacing clinker by other mineral
additive materials, and (iv) carbon capture and storage.
The incremental improvements in process efficiency have been adopted by the cement industry
in recent years, and the use of alternative fuels to reduce the fossil fuel combustion in cement
industry is now a standard in many countries, with some using a share of alternative fuels of more
than 50% of the total amount of fuel required for the thermal processing. And one way of reducing
CO
2
emission is the production of blended cements, which are formulated by blending of Portland
clinker (or Portland cement) with other finely ground mineral additives or supplementary
cementitious materials (SCMs) such as granulated blast furnace slag, fly ash, limestone powder, etc.
The partial replacement of clinker, which is not only the more expensive component of cement, but
also the most resource, energy and emission intensive, with mineral additives improve the
sustainability of the material. Carbon capture and storage (CCS) is to limit the release of CO
2
emissions, which generated from to the calcination of raw materials and fuel combustion in the
clinker production, into the atmosphere by capturing it and then storing it safely. Among the four
methods that cement plants have successfully applied or are trying to reduce CO
2
emitted from the
cement production, it will reviewed and evaluated on the standards in each region of the world to
the blended cement which reduces CO
2
emissions as well as the amount of energy used in cement
production, by lowering the clinker fraction with mixing of mineral additives’ powder in cement.
Cement standards are indispensable for the application in the building/civil engineering
industry. They provide obvious benefits in consumer protection with ensuring the quality and
consistency of products and services. Many countries throughout the world have their own
standards for cements, and furthermore, the use of blended cements is widely internationally
accepted and standardized to reduce CO
2
emissions from the cement industry, by the defining the
types and the blending fractions of mineral additives with clinker or cement. With the progressive
introduction of SCMs – blast furnace slag, fly ashes or other pozzolans and, in due time, limestone
fillers - the number of standardized cements has grown, including an increasing variety of
composite cements due to new combination of SCMs. The SCMs' compositions in the blended
cement are also more or less clearly defined in standards.
In the Europe, specifications of blended hydraulic cements are covered by the European
Standard (EN 197-1:2011, Cement Part 1: Composition, specification and conformity criteria for
common cements), in the Russia including central Asia by the Euro-Asian Standard (ГОСТ 31108-
90
2020, Cements for general construction), and in the U.S. by the American Society for Testing and
Materials (ASTM C595-16, Standard specification for blended hydraulic cement), respectively. In
addition to the above three regions of the world, standards related to each blended cement are
established according to the types of mineral additives that can be utilized in each country such as
China, India, Korea, Japan, Australia, and Canada, etc. Different standards and specifications across
the countries specify different cements types based on different criteria.
EN 197-1:2011 defines and gives the specifications of 27 distinct common cement products
and their constituents, in which cement includes the proportions of the constituents combined.
According to the specified proportions of 6 types of main constituents such as blast furnace slag (S),
silica fume (D), pozzolana consisting of natural (P) and natural calcined (Q) materials, fly ash
representing siliceous (V) and calcareous (W) materials, burnt shale (T), and limestone classifying
by the total carbon content not exceeding 0.50% (L) and 0.20% (LL) by mass. The Euro-Asian
Standard (ГОСТ 31108-2020)
suggests the 25 types of cement according to the blending of 8 types
of constituents, such as blast-furnace slag (Ш), microsilica (М
K
), pozzolan (П), gliezhi (Г), fly ash
(З), burnt shale (C), belite sludge (Бш), and limestone (И), in which gliezhi (Г) is defined as
thermally activated volcanic rocks and clays, burnt rocks, shales or sedimentary rocks, very similar
to natural calcined material (Q) in EN 197-1:2011.
The ASTM standard (ASTM C595-2016)
specifies two major groups of blended cements as (a) binary blended cements which consist of
Portland cement (PC) with either a slag, a pozzolan or a limestone and (b) ternary blended cements
which consists of PC with either a combination of two different pozzolans, a slag and a pozzolan, a
slag and a limestone or a pozzolan and a limestone, respectively.
By reviewing the blended cement standards of EN, ГOCT and ASTM, countries around the
world are establishing standards for the blended cement so that Portland cement (or clinker) can be
mixed with various types of mineral additives. Through these standards, it is possible to make good
use of the cementitious properties of mineral additives to be mixed, to preserve natural raw
materials through the use of industrial by-products, and to reduce CO
2
emissions as well as energy
consumption. Also, since it is already proved that the blended cement contributes to enhance the
various properties including workability, high strength, durability, and chemical resistance of
concrete, and it has advantages in terms of economy over Portland cement, it is necessary to expand
the use of the blended cement. In particular, since the natural and artificial resources for locally
available mineral additives that can be utilized in each country are different and limited, it is
necessary to actively review and develop locally available SCMs in each country, and the
application of blended cement have to be aggressively expanded for energy and CO
2
reduction by
making good use of the advantages according to the standard of blended cement. In order to pass on
a clean environment to future generations, the use of blended cement by selecting SCMs suitable
for supply and demand conditions in each country to reduce CO
2
, the main source of greenhouse
gas nowadays has become essential and irresistible.
Conclusion
The standard for blended cement is an important item that can solve to some extent the current
environmental problems such as global warming and energy problems. In Europe, Russia including
central Asia, the United States, and other countries, in order to respond to environmental problems,
standards related to blended cement have been established and revised, especially by subdividing
cement based on low-carbon blended cement using industrial by-products and allowing the use of
various mineral additives. In accordance with standards established in each region, it is necessary to
add acceleration to the direction corresponding to the realization of carbon neutrality, by promoting
and expanding the use of blended cement to reduce the CO
2
emission that countries around the
world are currently facing as well as to utilize various advantages of using blended cement.
Uzbekistan's cement industry should also make efforts to expand the market so that it can
actively utilize the advantages of the various physical properties of blended cement and the CO
2
reduction by using the already established standards.
