Investigation on key properties controlling early-age stress development of blended
, Will Hansen
Department of Civil Engineering, Bandung Institute of Technology, Ganeca 10, Bandung 40132, Indonesia
Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor MI 48109, USA
Received 9 May 2006
Accepted 5 May 2008
Age dependent mechanical and kinetic properties including Young's modulus, early-age creep, autogeneous
and thermal deformations, and heat of hydration were investigated for concrete made of blended cements.
These are among the key properties that control the early-age cracking behavior in hydrating concrete
members. Among the main goals of the investigation were to provide the experimental data and to study the
effect of adding mineral additives such as ﬂy ash (FA), ground granulated blast furnace slag (GGBF), and silica
fume (SF) on the aforementioned properties. The age-dependent behavior of Young's modulus, creep
compliance, and autogeneous shrinkage as functions of heat of hydration were modeled. We emphasized on
mathematical modeling the viscoelastic properties of concrete. The equations obtained can be used as inputs
needed to calculate the early-age stress development in concrete members.
© 2008 Elsevier Ltd. All rights reserved.
Temperature change and self-desiccation take place in concrete
during early ages where hydration occurs more rapidly. These behaviors
are followed by some dimensional changes including thermal dilation/
contraction and autogeneous shrinkage. The former comes from the
temperature variation inside concrete due to heat generated during
hydration and the ambient temperature variation. The latter is produced
from the volumetric changes of reacting phases before and after
hydration. Such changes are followed by a decrease in capillary pore
pressure and a decrease in solid surface energy. Both processes act as the
driving force for shrinkage. If the thermal and autogeneous deformations
are high enough and restrained due to the boundary conditions, stresses
can develop internally. When such stresses exceed concrete strength,
which is still relatively low at early ages, cracking may occur. This problem
has received some attention recently, and is often called the early-age
cracking. As our understanding about it is still developing, it is necessary
to investigate the key properties that control this behavior.
The early-age cracking is often observed in structures made with
low water cement to water ratio concrete which is a characteristic of
high-strength concrete. Within the last few decades, it has been
recognized that autogeneous deformation/shrinkage is larger in
concrete with low water to cement ratio and in concrete made with
silica fume [1–3]. However, due to their economical beneﬁts mineral
additives such as ﬂy ash, silica fume, and ground blast furnace slag have
been used in blended cements to improve the resistance against long
term environmental conditions such as chloride attacks  and freeze–
thaw cycles . Generally speaking, long term concrete performance is
strongly affected by its short term counterpart as concrete will have to
survive the early-age problems in order to guaranty a good long term
behavior. This makes it necessary to look at the short term behavior
like the early-age cracking, especially in blended cement concrete.
Early-age stresses develop with time and involve time dependent
properties like creep and other mechanical properties that are
strongly inﬂuenced by hydration such as strength and Young's
modulus [6–10]. Several studies have been dedicated to investigating
creep behavior of concrete which have included looking at the
difference between compressive and tensile behaviors [11–16]. Some
of these studies have been conducted to obtain early-age creep
properties [6,15,16].From[13,14], concrete creep under tension and
compression were also known to be different. Creep in tension was
about 20% higher than creep in compression. Analyzing the risk of
cracking at early ages favors the use of tensile creep since concrete
cracks under tension at early ages.
Sources of early-age deformations are temperature change and
self-desiccation. The deformations caused by both factors above are
inﬂuenced by hydration. Self-desiccation behavior has been found to
Cement and Concrete Research 38 (2008) 1325–1335
⁎ Corresponding author. Tel.: +62 22 251 0715.
E-mail address: email@example.com (I. Pane).
0008-8846/$ – see front matter © 2008 Elsevier Ltd. All rights reserved.
Contents lists available at ScienceDirect
Cement and Concrete Research
journal homepage: http://ees.elsevier.com/CEMCON/default.asp