1
25-068
Past, Present, and Future of Cement Manufacturing and
Decarbonization in the United States
Duah Philip
Missouri University of Science &Technology,
Rolla, MO, USA
Awuah-Offei Kwame
Missouri University of Science &Technology,
Rolla, MO, USA
ABSTRACT
Regulatory pressure to mitigate the cement industry’s envi-
ronmental impact has intensified recently, spurring inno-
vation in low-carbon cement technologies. In the United
States, cement production, consumption, and carbon emis-
sions are accelerating. Despite this trend, the adoption of
environmentally friendly dry clinker production technology
with combined preheater-precalciner systems has surged
from 53.3% in 2002 to 88.5% in 2019. Concurrently, reli-
ance on wet technologies, known for their higher environ-
mental impact, has dropped from 16.5% to 0.6% within
the same period. This paper presents the results of our com-
prehensive study, utilizing over 100 years of industry data,
to analyze these technological shifts and their environmen-
tal implications.
INTRODUCTION
Portland cement (henceforth referred to as cement) is an
essential material in the construction industry, acting as a
binding agent in both concrete and mortar. Cement pro-
duction follows a consistent process despite varying manu-
facturing technologies (Figure 1). Raw materials such as
limestone, clay, gypsum, iron ore, and others are either
obtained from quarries or other sources and are transported
to manufacturing plants via multiple modes (Athena
Sustainable Materials Institute, 2021). The manufacturing
process involves comminution and proportioning of raw
materials, followed by pyroprocessing in kilns using dif-
ferent clinker technologies with varying energy efficiencies
(Hottle et al., 2022). During clinker production, limestone
(CaCO3) is heated to 1400–1450°C, producing CaO and
CO2, with a raw material to clinker ratio of 1.59 (Portland
Cement Association, 2021). The final cement product is
obtained by grinding cooled clinker with approximately
5% gypsum.
The cement industry is widely recognized as a hard-
to-abate sector due to its significant greenhouse gas emis-
sions from both fuel combustion and calcination (Paltsev
et al., 2021). In the clinker production process, which is
responsible for 85% of total cement manufacturing emis-
sions, calcination contributes 51% while fuel consumption
accounts for 34% of these emissions (U.S. Department of
Energy, 2023). While cement production represents 0.7%
of total U.S. greenhouse gas emissions (U.S. EPA, 2024a),
globally, the sector contributes 8% of total CO2 emissions
(Andrew, 2018).
Taken together, these findings suggest an imperative for
decarbonization within the cement industry. With the chal-
lenge of decarbonizing hard-to-abate cement industrial sec-
tor, also comes an opportunity. To advance decarbonization
in this sector, in recent years, various innovative technolo-
gies, novel cement chemistries and strategies to significantly
reduce emissions in the cement sector has been proposed.
Cement manufacturing companies are increasingly adopt-
ing supplementary cementitious materials (SCMs) to lower
the clinker content in their cement product, which can lead
to substantial emissions reductions thereby advancing cir-
cular economy since SCMs such as fly ash, municipal solid
waste incineration ash, steel slag etc. are industrial wastes.
In this study, where possible, the decarbonization of con-
crete will be generically addressed in tandem with cement.
This is because concrete production’s inherent carbon foot-
print stems largely from the carbon emissions originat-
ing from cement manufacturing process (with emissions
sources predominantly coming from fossil fuel combustion
and calcination noted earlier).
25-068
Past, Present, and Future of Cement Manufacturing and
Decarbonization in the United States
Duah Philip
Missouri University of Science &Technology,
Rolla, MO, USA
Awuah-Offei Kwame
Missouri University of Science &Technology,
Rolla, MO, USA
ABSTRACT
Regulatory pressure to mitigate the cement industry’s envi-
ronmental impact has intensified recently, spurring inno-
vation in low-carbon cement technologies. In the United
States, cement production, consumption, and carbon emis-
sions are accelerating. Despite this trend, the adoption of
environmentally friendly dry clinker production technology
with combined preheater-precalciner systems has surged
from 53.3% in 2002 to 88.5% in 2019. Concurrently, reli-
ance on wet technologies, known for their higher environ-
mental impact, has dropped from 16.5% to 0.6% within
the same period. This paper presents the results of our com-
prehensive study, utilizing over 100 years of industry data,
to analyze these technological shifts and their environmen-
tal implications.
INTRODUCTION
Portland cement (henceforth referred to as cement) is an
essential material in the construction industry, acting as a
binding agent in both concrete and mortar. Cement pro-
duction follows a consistent process despite varying manu-
facturing technologies (Figure 1). Raw materials such as
limestone, clay, gypsum, iron ore, and others are either
obtained from quarries or other sources and are transported
to manufacturing plants via multiple modes (Athena
Sustainable Materials Institute, 2021). The manufacturing
process involves comminution and proportioning of raw
materials, followed by pyroprocessing in kilns using dif-
ferent clinker technologies with varying energy efficiencies
(Hottle et al., 2022). During clinker production, limestone
(CaCO3) is heated to 1400–1450°C, producing CaO and
CO2, with a raw material to clinker ratio of 1.59 (Portland
Cement Association, 2021). The final cement product is
obtained by grinding cooled clinker with approximately
5% gypsum.
The cement industry is widely recognized as a hard-
to-abate sector due to its significant greenhouse gas emis-
sions from both fuel combustion and calcination (Paltsev
et al., 2021). In the clinker production process, which is
responsible for 85% of total cement manufacturing emis-
sions, calcination contributes 51% while fuel consumption
accounts for 34% of these emissions (U.S. Department of
Energy, 2023). While cement production represents 0.7%
of total U.S. greenhouse gas emissions (U.S. EPA, 2024a),
globally, the sector contributes 8% of total CO2 emissions
(Andrew, 2018).
Taken together, these findings suggest an imperative for
decarbonization within the cement industry. With the chal-
lenge of decarbonizing hard-to-abate cement industrial sec-
tor, also comes an opportunity. To advance decarbonization
in this sector, in recent years, various innovative technolo-
gies, novel cement chemistries and strategies to significantly
reduce emissions in the cement sector has been proposed.
Cement manufacturing companies are increasingly adopt-
ing supplementary cementitious materials (SCMs) to lower
the clinker content in their cement product, which can lead
to substantial emissions reductions thereby advancing cir-
cular economy since SCMs such as fly ash, municipal solid
waste incineration ash, steel slag etc. are industrial wastes.
In this study, where possible, the decarbonization of con-
crete will be generically addressed in tandem with cement.
This is because concrete production’s inherent carbon foot-
print stems largely from the carbon emissions originat-
ing from cement manufacturing process (with emissions
sources predominantly coming from fossil fuel combustion
and calcination noted earlier).