Environmental Engineering Reference
In-Depth Information
the importance of the aggregate-cement interfaces
in these kinds of concretes and the water/cement
ratio in the strength properties.
Topçu (2008) studied the use of aPe both as
an aggregate and as a cement addition in order to
improve density and strength in lightweight con-
crete blocks. The perlite powder has a pozzolanic
effect on concrete mixtures despite the potential
alkali-aggregate reaction.
Table 1. Physics characteristics of the Thermocal
TM
mortar (GP-csiii-W2-T1).
Physical properties
Units
Value
0.068
λ Thermic conductivity
W/m⋅k
steam permeability
ml/cm
2
48 h
<8.46
Water absorption
0.2
kg/mm
2
⋅min⋅0,5
specific heat (MDsc)
kJ/ kg⋅k
0.823
Powder density
kg/m
3
350
Mixer water
%
54
consistence
mm
135
2
eXPeRiMenTal sTUDY
Fire resistance
class
a1
2.1
Materials
2.1.1
Portland cement with pozzolan
For this study portland cement with pozzolanic
additions type ceM ii/ a-P 32,5R was used. This
is the most commonly used cement in masonry
production in the canary islands. This cement
has 80-94% of clinker and 6-20% of natural poz-
zolan in accordance with Une en 197-1:2000
regulations. This type of cement reduces hydraulic
retraction and heat hydration in lightweight con-
crete mixtures, and therefore improves the concrete
block surface. The use of cement with less compres-
sive strength entails an increase in the amount of
cement needed to get a certain mechanical strength
from the concrete block, which improves the batha-
bility of the aggregates. This is important in light-
weight concretes with volcanic slag aggregates
(Vsa) that are produced using dry mixtures. soria
(1972) demonstrated that pozzolan contribution is
greater in poor blended and in high cement-water
ratio concrete mixtures, always with a moist cure.
This is why, in the manufacture of Bhic, cement
with pozzolanic additions is the most appropriate
for mixtures having a small quantity of cement.
Table 2. Mechanical characteristics of the Thermocal
TM
mortar (GP-csiii-W2-T1).
Mechanical properties
Units
Value
compressive strength (14 days)
n/mm
2
2.4
compressive strength (28 days)
n/mm
2
4.3
Flexural strength (14 days)
n/mm
2
0.1
Flexural strength (28 days)
n/mm
2
1
adhesion
n/mm
2
>0.1
Table 3.
Physical test on 0-4 mm natural yellow sand.
Physical properties
Units
Value
Fines percentage
%
18.3
Friability coefficient
F.a
30
sand equivalent
index
29
absorption
%
0.8
Dry real density
g/cm
3
2.7
Water content
%
3.4
form. however, its composition varies depending
on the local rock conditions. in general, the fine
aggregate or sand will not contain clay, lime, alkali,
organic material and other harmful substances,
in accordance with regulations. The sand or fine
aggregate used in the study is a polygenic and par-
tially calcareous sand. a granular test was made
in accordance with Une-en 933-1 and Une en
933-2:1996 regulations. see Table 3.
2.1.2
Thermocal
TM
Thermocal
TM
(TheR) is an ecologic mortar which
acts as a thermal and acoustic corrector and is used
as a covering for external building walls. its main
property is its low density and resistance to water
permeability. Tables 1 and 2 show the physical and
mechanical properties of the Thermocal
TM
used in
this study.
2.1.5
Volcanic lapilli aggregate (AEV 0-12 mm
and AEV 0-8 mm)
Volcanic slag aggregate (aeV), also called “lapilli”,
are small, dark-coloured pyroclastic fragments,
with 8.5% to 33% of pores. This high porosity is
the cause of their low density. They come from
basic magma and they are usually related to strom-
bolian-type eruptions (lomoschitz et al. 2006). The
lack of reactive silica eliminates the problems of
alkali-silica reactivity with portland cement. They
are sharp edged, angular and typically reddish to
black in colour, mostly due to their high iron con-
tent (Demirdag & Gündüz. 2008). 85% of these
2.1.3
Mixture water
The mixture water employed in this study is in
accordance with the spanish structural concrete
code (ehe-08). The water is the same as the one
used in the precast concrete industry where the
tests were carried out.
2.1.4
Natural yellow sand
in geological terms, sand is a granular material
with a variable size between 0.063 and 4 mm. it
is mainly composed of silica, generally in quartz
