Nanoscience and nanoengineering of cement-based materials - Nanotechnology in Eco-efficient Construction - page 7

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Nanoscience and nanoengineering of
cement-based materials

G. CONSTANTINIDES, Cyprus University of
Technology, Cyprus

DOI : 10.1533/9780857098832.1.9

Abstract : Concrete is the most widely used construction material and
given the current population growth, economic development, and need
for repair/replacement of aging infrastructure, its consumption is
expected to increase. Unfortunately though, the production of one of its
major constituents, cement, is associated with approximately 5-10% of
the global anthropogenic carbon dioxide emissions and therefore the
industry and the specifi c material is in urgent need for reevaluation.
The chemical reactions and resulting products that are produced when
cement is mixed with water create a material that is highly complex. The
dominant component, C-S-H gel, has a local structure of a precipitate
with nanoscale features that are diffi cult to model and understand.
Consequently, the development of the material relied primarily on
empirical knowledge obtained through macroscopic experimentation
and little is known about the underlying mechanisms that control the
response of the material when employed in engineering applications.
Recent experimental and theoretical advancements in the fi eld of
nanoscience and nanotechnology provide optimistic expectations for a
refi ned understanding of the material that will create the scientifi c basis
for a more sustainable and eco-effi cient construction.

Key words : concrete nanoscience, concrete nanoengineering, C-S-H
nanomechanics, concrete nanocomposites.

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2.1 Introduction

2.1.1 Macroscale: cement and concrete

Cement is a pulverized fi ne powder which develops into a strong binder
when mixed with water. The best known hydraulic cement 1 is ordinary
Portland cement (OPC). Current production of cement (the main compo-
nent of concrete and all other cement-based materials) is approximately
over 3 billions tonnes per year which makes it the most widely used solid
on earth (Fig. 2.1). This quantity is suffi cient to produce over 30 billions
tonnes of concrete or over 4 tonnes for every person currently alive. Given

1 By the term 'hydraulic cement', we refer to those materials whose products are stable in
aqueous environments.

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