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Aims
• The aim of this research is to produce foamed concrete
with/without lightweight aggregate which is suitable for structural
purposes with good insulation and durability properties and to
evaluate its damage behaviour.
Objectives • Produce a range of structural and non-structural foamed
concretes with varying insulation and durability properties.
• Study and understand how microstructure affects the properties
and damage mechanisms of foamed concrete under mechanical
loading.
• Investigate and understand mechanisms of stress-induced
damage (micro and macrocracks) in this type of lightweight
Introduction
• Cellular (aerated) concrete is a lightweight material composed of
cementitious mortar surrounding disconnected bubbles in which
either air is introduced into the mortar mixture or gas is formed
within it.
• Foamed concrete is a versatile material consisting of either
Portland cement paste or cement filler matrix (mortar) with
homogeneous pore structure created by entrapped air voids
roughly 0.1-1.0 mm size. It can be divided into two groups:
physically foamed concrete (by using foaming agents) and
chemically foamed concrete (by adding aluminium powder).
Results • The compressive strength
of foamed concrete (ƒcu) is
affected by such factors as
density, age, cement content,
w/c ratio, s/c ratio, foam
volume, additives and curing. Its
relation with age is shown below.
• Microstructural
Investigation:
On Progress
Study the effect of
in terms of air voids system and
ITZ characteristics on the
mechanical, thermal and fracture
behaviour of foamed concrete.
• Damage Evaluation:
damage study of micro and macro levels will be performed on the
selected mixes by using several techniques classified into
surface observations Digital Image Correlation (DIC) and
Electronic Speckle Pattern Interferometry (ESPI) and internal
observations Acoustic Emission (AE), Scanning Electron
Microscopy (SEM) and X-ray CT system
Foamed Concrete
Cement
Air
Bubbles
Sand
Water
concrete by using several techniques classified into
surface observations, internal observations as
well as standard fracture energy tests.
Foam
Additives
Ordinary
Mixer
Cement Water Binder
Moulding
Curing
Product
Foam
Generator
Foaming Agent
Water
Solution
Compressed
Air
Foam generator used (STONEFOAM-4)
Microstructural characteristics
• Fracture Characterization:
to characterize a fracture of foamed concrete, two fracture
parameters models will be required: fracture toughness (KIc), a
property which characterises the resistance of a material to
crack propagation, and critical crack tip opening displacement
(CTOD) will be adopted.
• By using a scanning electron microscope (SEM) with secondary
electron mode, a few images were captured for three samples
(20×20×10 mm) which were cut from different positions of a cube
specimen. In order to characterize the cracks inside a specimen
exposed to compressive loading, a sequence of 2D images was
captured through the height of the 100mm cube with a slice
thickness of 1 mm using the non-destructive X-ray CT system.
0
5
10
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0 7 14 21 28
Co
mp
ress
ive
Str
eng
th (
MP
a)
Age (day)
FC1300
FC1600
FCa1600
FCa1600
FCa1800
FCA1600
FCAa1600
Microstructure of two types of
foamed concrete, (Just and
Middendorf, 2009).
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