Air content of self-consolidating concrete and its mortar phase including rice husk ash/Oro kiekis savitankiame betone ir jo skiedinio dalyje su ryziu lukstu pelenais.
Safiuddin, Md. ; West, Jeffrey S. ; Soudki, Khaled A. 等
1. Introduction
Self-consolidating concrete (SCC) is relatively a new development
in concrete technology. It is a highly flowing concrete that spreads
under self-weight to reach each and every corner of the formwork, and is
consolidated without any external means such as rodding or vibration
(Khayat 1999; EFNARC 2002). SCC is a good choice for many concrete
structures where placement and consolidation of ordinary concrete are
complicated due to intricate formwork shape and congested reinforcing
bars. It requires several additional constituent materials such as
supplementary cementing material (SCM) and high-range water reducer
(HRWR) in addition to the basic ingredients of ordinary concrete. SCC
must need HRWR to achieve the self-consolidation capacity in fresh state
(Safiuddin 2008; Safiuddin et al. 2010a). It can also include SCM mainly
to improve the strength and durability of concrete (Safiuddin et al.
2010b). However, both SCC and ordinary concrete must need air-entraining
admixture (AEA) to obtain entrained air content for enhanced durability
or extended service life in freezing and thawing environment.
Adequately high air content (4-8%) is essential to improve the
durability of concrete exposed to freezing and thawing environment (ACI
Committee 318 2009; Jana et al. 2005; Kosmatka et al. 2009; Persson
2003). For this, a sufficient dosage of AEA must be used in concrete. An
AEA incorporates millions of noncoalescing microscopic air bubbles in
fresh concrete and forms a network of air-voids in hardened concrete.
The air-voids perform as pressure releasing valves to reduce the
hydraulic stresses caused by the freezing water, and thus improve the
durability performance of concrete in freezing and thawing environment
(Chatterji 2003; Powers 1949; Sun and Scherer 2010).
Achieving the target air content in concrete is not a
straight-forward task. It is more fastidious for SCC because of its
highly fluid nature and complex admixture systems. Excessive fluidity
may cause air-void instability problem in SCC leading to a reduction in
concrete air content (Szwabowski and Lazniewska-Piekarczyk 2009). In
addition, the air bubbles may reduce the segregation resistance of SCC
by affecting its yield stress and plastic viscosity (Bonen and Shah
2005; Carlsward et al. 2003; Khayat 2000). When the segregation
resistance is reduced, the air content of SCC consequently can be
affected due to the upward movement and escape of air bubbles. The
presence of HRWR also tends to destabilize the entrained air bubbles
during transport and placement of concrete leading to a reduction in air
content (Khayat and Assaad 2002; Safiuddin et al. 2006; Saucier et al.
1990). Furthermore, aggregate grading, cement composition, type and
re-dosing of HRWR, mixing and placing methods, re-mixing of concrete,
type and composition of SCM, cement-admixture compatibility, type of AEA
and ambient temperature influence the air-entrainment and air-void
stability in SCC (ACI Committee 201 2008; Carlsward et al. 2003; Du and
Folliard 2005; Shetty 2007; Zhang and Wang 2005). For example,
polycarboxylate-based HRWR induces additional air-voids in SCC by
decreasing the surface tension of the liquid phase in paste (Szwabowski
and Lazniewska-Piekarczyk 2009). In contrast, RHA causes a loss of
air-voids in SCC by increasing the yield stress and plastic viscosity of
concrete (Safiuddin 2008; Safiuddin et al. 2006). A similar effect can
be observed for other SCM. Therefore, achieving the target air content
in SCC is most often problematic. A number of trial mixtures can be
required to determine the AEA dosage for target air content. It may
cause a significant loss of materials, labour, and construction time
resulting in an uneconomical concrete production. This problem can be
resolved if it is possible to estimate the AEA dosage for a target air
content before concrete production.
In the present study, a number of air-entrained SCC mixtures were
produced including RHA as an SCM. The effects of W/B ratio and RHA
content on the air content of SCC and its mortar phase are discussed in
this study. The effect of mortar volume on the concrete air content is
also shown in this study. In addition, the present study demonstrates a
simple technique to estimate the AEA dosage for air-entrained SCC based
on the air content of its mortar phase.
2. Experimental Methods
2.1. Constituent materials
A blend of crushed and round aggregates with an equal mass was used
as the coarse aggregate (CA). The fine aggregate (FA) used was natural
pit sand. The aggregates had low absorption value and fines (< 75
[micro]m) content. In addition, both fine and coarse aggregates
fulfilled the ASTM C33/C33M-08 (2008) grading requirements, as can be
seen from Figs 1 and 2.
[FIGURE 1 OMITTED]
[FIGURE 2 OMITTED]
Normal portland cement (C) conforming to the ASTM C150/C150M-09
(2009) specifications was used as the main cementing material. Amorphous
RHA was used as an SCM. The use of RHA widened the range of AEA dosage,
since it increases the AEA demand to achieve specified air content in
concrete (Safiuddin et al. 2006; Zhang and Malhotra 1996). Cement and
RHA together acted as the binder (B). The normal tap water (W) was used
as the mixing water for preparing the mortars and concretes. In
addition, a polycarboxylate-based HRWR and a synthetic AEA were used to
produce the required flowing ability and air content, respectively. The
major physical properties of the constituent materials are given in
Table 1. Most of these properties were useful to obtain the mixture
proportions of mortars and concretes.
The particle size distributions of cement and RHA are shown in Fig.
3. This figure shows that the median particle size of RHA was 6 [micro]m
whereas that of cement was 15 [micro]m. Moreover, it can be seen from
this figure that about 98% of RHA (by mass) was finer than 45 [micro]m.
The mass finer than 45 [micro]m was around 91% in the case of cement.
[FIGURE 3 OMITTED]
The chemical compositions of cement and RHA are given in Table 2.
RHA had a mass-based silica content of 93.6%. It suggests that the RHA
used was a highly reactive pozzolanic SCM, which is also obvious from
the high accelerated pozzolanic activity index of 122.4% (refer to Table
1). The deleterious components of cement such as MgO, S[O.sub.3], and
insoluble residue were below the maximum limits, as specified in ASTM
C150/C150M-09 (2009). However, the equivalent alkalis of both cement and
RHA were slightly higher than the maximum allowable limit of 0.6% (ASTM
C150/C150M-09 2009), which was acceptable in the absence of reactive
aggregates. The loss on ignition (LOI) was below the maximum permissible
limit of 3% (ASTM C150/C150M-09 2009) for both cement and RHA. Also, the
RHA possessed a very low carbon content of 0.15% (by mass), which had a
negligible impact on the air entrainment in mortars and concretes.
2.2. Concrete mixture proportions and designations
Different types of air-entrained SCC mixtures were designed based
on the optimum sand/aggregate (S/A) ratio of 0.50. The optimum S/A ratio
was obtained based on the maximum bulk density of sand-coarse aggregate
blends (Safiuddin 2008; Safiuddin et al. 2010a). The major design
variables for the concrete mixtures were water/binder (W/B) ratio
(0.30-0.50), RHA content (030%), and air content (4-8%). The mixture
proportions (including HRWR dosages) and designations of the concretes
are shown in Table 3. The concrete mixtures were designated based on the
W/B ratio, RHA content, and design air content used. For example, the
'C30R0A6' designation was chosen for a concrete prepared with
a W/B ratio of 0.30, 0% RHA content, and 6% design air content.
2.3. Mortar mixture proportions and designations
The mortars were formulated from their parent concretes. The
proportions of fine aggregate (pit sand), cement, RHA, and water were
determined based on the mixture proportions of the corresponding parent
concretes. The mortars prepared separately had the same composition as
the mortar phase of tested concretes. The dosages of HRWR were fixed at
the saturation dosages. The saturation dosages of HRWR were obtained
based on the flowing ability of the paste phase of mortar and concrete
(Safiuddin 2008). The mixture proportions (including HRWR and AEA
dosages) and designations of the mortars are given in Table 4. The
mortars were designated based on the W/B ratio, RHA content, and design
air content of the corresponding parent concretes. For instance, the
'M30R0A6' designation was selected for the mortar prepared
with a W/B ratio of 0.30, 0% RHA content, and 6% design air content, as
used in the corresponding parent concrete 'C30R0A6'.
2.4. Preparation and testing of mortars
The mortars were prepared using an epicyclic revolving type small
mechanical mixer. The volume of the mortars produced was 3 liters. In
preparing the mortars, the fine aggregate and binding material (cement
alone or with RHA) were first dry-mixed for 1 min by a stainless spoon.
After that, the mixing water including the initial dosage of AEA was
added into the mixer bowl and a rest period of 30 s was allowed. Then
the mixer was started, the HRWR dosage was gradually added, and the wet
mixing was conducted for 3 min. Later, the subsequent AEA dosages were
used to vary the air content of the mortars. For each incremental AEA
dosage, further mixing was conducted for 2 min. The Chace indicator test
(refer to Fig. 4) was carried out to determine the mortar air content
immediately after the completion of mixing. The AASHTO T 199 (2008)
standard procedure was followed except for filling the brass cup, where
the mortar was placed without any rodding. The mortars were also tested
for the flowing ability with respect to the flow spread using a standard
flow mould. The details of this test are described in Safiuddin (2008)
and Safiuddin et al. (2011).
2.5. Preparation and testing of fresh concretes
The fresh SCC mixtures were prepared using a revolving pan type
mixer. The volume of the concretes produced was 25 liters. The dosages
of HRWR were fixed based on the saturation dosages. The HRWR dosages
used in most concretes were 70-80% of the saturation dosages. The
dosages of AEA were decided based on the estimated AEA dosages obtained
from the air content test results of the mortars. The AEA dosage was
incorporated at the beginning whereas the HRWR dosage was added at the
later stage of mixing. The net mixing time for all concretes was 7 min.
Immediately after the completion of mixing, the fresh concretes were
tested for the air content. The ASTM C231-08 (2008) standard method was
applied using a Type B air meter (refer to Fig. 5) with some exceptions
for pouring and consolidation. The measuring bowl of the air meter was
filled with the fresh concrete in one layer and without any
consolidation. The fresh SCC mixtures were also tested for the flowing
ability by a number of standard and non-standard tests to ensure that
the concretes possessed sufficient self-consolidation capacity. The
details of these tests are depicted in Safiuddin (2008) and Safiuddin et
al. (2010a).
[FIGURE 4 OMITTED]
3. Test Results and Discussion
The mortars prepared were highly flowable. The flow spread of the
mortars at HRWR saturation dosages varied in the range of 238-317 mm,
which generally suggests an excellent flowing ability of SCC possessing
a slump flow of 550-850 mm (Jin and Domone 2002; Safiuddin et al. 2010a;
SCCEPG 2005). Indeed, the slump flow of various SCC mixtures produced in
the present study differed in the range of 605-770 mm, as can be seen
from Table 5. The other flow tests also exhibited the excellent flowing
ability of SCC mixtures. The detailed test results for the flowing
ability of mortars and concretes are reported in Safiuddin et al.
(2010a, 2011). The present paper only emphasizes the air content results
of various SCC mixtures and their mortar phases.
[FIGURE 5 OMITTED]
3.1. Air content of mortars
The results of the air content for different mortars are presented
in Figs 6 to 9. The air content curves presented in Figs 6 to 8 are for
the mortars formulated from the concretes with 6% design air content. In
contrast, the air content curves shown in Fig. 9 are for the mortars
formulated from the concretes with 4% and 8% design air contents. In
general, the measured air content of the mortars varied from 3.7% to
19.4% for the AEA dosages used in the range of 0.5-4 ml. The air content
of the mortars increased with increasing AEA dosages. This is mainly due
to the formation of more air-voids from higher AEA dosage. Moreover,
some additional air-voids leading to greater total air content can be
produced from the previous AEA dosages with increased mixing time
(Kosmatka et al. 2009; Safiuddin et al. 2006).
[FIGURE 6 OMITTED]
[FIGURE 7 OMITTED]
[FIGURE 8 OMITTED]
The mortar air content curves shown in Figs 6 to 8 shifted to the
downward direction with lower W/B ratio (higher binder content) and
greater RHA content, indicating a decrease in air content. The effects
of W/B ratio and RHA content on the air content of mortars are more
evident from Figs 10 and 11, respectively.
[FIGURE 9 OMITTED]
[FIGURE 10 OMITTED]
[FIGURE 11 OMITTED]
The binder content increased at a lower W/B ratio and resulted in a
higher surface area. Also, the surface area of the binder significantly
increased in the presence of RHA due to its porous honeycomb
microstructure. The greater surface area decreased the available free
water content in mortar. Consequently, the yield stress and plastic
viscosity of mortar were increased. The increase in the yield stress was
indicated by the flowing ability (flow spread) results of the mortars.
The details of these results are given in Safiuddin et al. (2011). The
flow spread is strongly correlated with the yield stress by an inverse
linear relationship (Murata 1984; Safiuddin et al. 2010a;
Schwartzentruber et al. 2006). The yield stress is a fundamental
rheological property of cement-based materials as described in Bingham
model (Chidiac and Habibbeigi 2005). Because of the inverse
relationship, the higher the yield stress, the lower is the flow spread.
Thus, a decrease in the flow spread reported in Safiuddin et al. (2011)
was associated with an increase in the yield stress of mortar.
Moreover, the estimated yield stress of concrete increased with
lower W/B ratio and higher RHA content (Safiuddin et al. 2010a). The
same effect (increase in yield stress) is also expected for mortar,
since the rheological behaviors of mortar and concrete are similar
(Banfill 1994). The increased yield stress suggests a loss of air-voids
(Carlsward et al. 2003; Chidiac et al. 2003) from mortar, as the
air-voids offset the forces of attraction between the solid particles in
suspension. Furthermore, the increase in the plastic viscosity of mortar
was denoted by the flowing ability (flow time) results of the paste
phase of mortar or concrete. The details of these results are given in
Safiuddin et al. (2010a). The flow time is strongly correlated with the
plastic viscosity by a direct linear relationship (Safiuddin et al.
2010a; Schwartzentruber et al. 2006). The plastic viscosity is another
fundamental rheological property of cement-based materials behaving as a
Bingham fluid (Chidiac and Habibbeigi 2005). Owing to the direct
relationship, the greater the plastic viscosity, the higher is the flow
time. Thus, the increased flow times of the paste and concrete reported
in Safiuddin et al. (2010a) indicated a greater plastic viscosity of
mortar. The estimated plastic viscosity of concrete shown in Safiuddin
et al. (2010a) also suggested that the mortar plastic viscosity
increased with lower W/B ratio and higher RHA content. The increased
plastic viscosity caused to decrease the air content of mortar. This is
because the increased plastic viscosity tends to collapse some of the
air-voids with higher internal pressure (Khayat and Assaad 2002). The
collapsed air-voids can easily go out of the mortar at a high
consistency maintained in the presence of HRWR. Besides, the increased
RHA content required higher dosages of HRWR. The HRWR molecules impede
the attachment of entrained air-voids onto the binding materials by
reducing the attachment sites (Khayat and Assaad 2002). On the whole,
the mortar air content decreased with lower W/B ratio and higher RHA
content. This finding implies that the aeration problem of
polycarboxylate-based HRWR was minimized in the present study. This is
due to the combined effect of increased flowing ability, presence of
RHA, and cement-admixture compatibility.
The mortar air content curves shown in Fig. 9 reveal that the air
content of M35R0A4, M35R15A4 and M35R20A4 was lower than that of
M35R0A8, M35R15A8 and M35R20A8, respectively, for given W/B ratio, RHA
content, and AEA dosage. This is mostly due to the greater sand (fine
aggregate) content of mortar. The sand content of M35R0A4, M35R15A4 and
M35R20A4 was higher than that of M35R0A8, M35R15A8 and M35R20A8, as can
be seen from Table 4. The higher sand content increases the yield stress
and plastic viscosity of mortar due to confinement of some mixing water
and enhanced interaction of sand particles, and thus destroys certain
amount of the air-voids (Banfill 1994; Sa fiuddin 2008).
3.2. Estimated AEA dosages of concretes
The AEA dosages required to produce the target air content in
concretes were estimated based on the air content results of the
mortars. For this, the entrained concrete air content (design air
content - entrapped air content) was converted into the equivalent
mortar air content. Eq. (1) was used to determine the equivalent air
content of the mortar phase (ASTM C231-08 2008):
[A.sub.me] = 100 [A.sub.c] [V.sub.c]/100 [V.sub.m] + [A.sub.c]
([V.sub.c] - [V.sub.m]), (1)
where: [A.sub.me]-equivalent air content of mortar (%);
[A.sub.c]-entrained air content of concrete (%); [V.sub.c] - air-free
absolute volume of concrete ([m.sup.3]); [V.sub.m] - air-free absolute
volume of the mortar phase of concrete ([m.sup.3]).
The AEA dosages needed for the equivalent mortar air contents were
calculated using the air content curves presented in Figs 6-9. These AEA
dosages are applicable for the pure mortars, which were prepared
separately instead of taking from the concrete mixtures. Hence, they
were corrected by multiplying with the actual air-free volume fraction
of the mortar present in concrete. Eq. (2) was applied to estimate the
AEA dosages for the concretes. The estimated AEA dosages of different
concretes are given in Table 5.
[D.sub.ce] = [D.sub.me] [R.sub.d]/1000 B x [[phi].sub.mc x 100, (2)
where: B--binder content of mortar (kg); [D.sub.ce]--estimated AEA
dosage for the specified air content of concrete (% B);
[D.sub.me]--dosage of AEA for the equivalent air content of mortar (ml);
[R.sub.d]--relative density of AEA; [[phi].sub.mc]--mortar volume
fraction of concrete ([m.sup.3]/[m.sup.3]).
3.3. Actual AEA dosages and air contents of concretes
The actual AEA dosages used and the actual (measured) air content
for various SCC mixtures are shown in Table 5. The actual air contents
were within [+ or -] 1.0% of the design air content. This variation is
acceptable, as the maximum acceptable tolerance for air content
measurement can be in the range of [+ or -] 1.5% (ACI Committee 201
2008). However, the air content of SCC was prone to decrease with lower
W/B ratio and higher RHA content. Also, the aeration effect of
polycarboxylate-based HRWR was not pronounced in SCC mixtures, as
understood based on the results of concrete air content test. Hence, the
concrete with lower W/B ratio and higher RHA content needed a greater
AEA dosage, as evident from Table 5. The reasons are the same as
discussed in the case of mortar air content. In addition, the mortar
volume influenced the air content of concrete. Depending on the W/B
ratio and design air content, the increased mortar volume caused to
decrease the air content of concrete due to the similar reasons as
discussed in section 3.1. Therefore, more AEA dosage was required to
achieve the target air content in concrete, as can be seen from Fig. 12.
3.4. Correlation of estimated and actual AEA dosages
The correlation between the actual and estimated AEA dosages of SCC
was established. An excellent correlation (Fig. 13) between the
estimated and actual AEA dosages was obtained for SCC despite its
critical nature for airvoid stability. The relationship was linear with
a correlation coefficient of 0.967, as can be seen from Fig. 13. Some
variations between the estimated and actual AEA dosages were detected
possibly due to the differences in ambient environment, batch volume,
mixture composition, mixing time, and type of mixer that occurred from
mortar to concrete. However, the observed correlation suggests that the
AEA dosage required for an air-entrained SCC can be determined based on
the air content of its mortar phase. A similar correlation is also
expected for the other types of concrete. This is because the concept of
equivalent mortar air content can be applied to other concretes.
Besides, achieving such correlation for a concrete other than SCC can be
much easier due to the reduced risk of air-void instability.
[FIGURE 12 OMITTED]
[FIGURE 13 OMITTED]
4. Research Significance
The present study reports the air content results of various SCC
mixtures and their mortar phases including RHA, and demonstrates a
simple technique to estimate the AEA dosage for the target air content
in concrete. The technique presented in this study will minimize the
volume of experimental work to determine the AEA dosage for concrete. It
will be cost-effective due to the minimum number of concrete trial
mixtures, thus reducing the loss of materials and labor. In addition,
the apparatus (Chace indicator) needed for this technique is less
expensive than other air content measuring equipment such as air void
analyzer (Baekmark et al. 1994; Lane 2006; Zhang and Wang 2005). The
demonstrated test method is also very fast because of simplicity. The
entire test can be conducted by less than 10 min. Also, the same mortar
batch can be used with additional AEA dosage if needed. The quick and
simple procedure can allow repeating the test without any significant
loss of air-voids. This will accelerate the process of determining the
AEA dosage for the target air content in concrete.
5. Conclusions
The following conclusions can be drawn from the results of the
present study dealing with the air content of SCC and its mortar phase:
a. The air content of the mortars increased with the increase in
AEA dosage due to the formation of more air-voids, and decreased with
lower W/B ratio and higher RHA content because of the increases in
binder content, binder surface area, and HRWR dosage.
b. The air content of the mortars for given W/B ratio, RHA content,
and AEA dosage decreased with increased sand content due to the water
confinement and greater interaction of sand particles.
c. The air content of the mortars facilitated to estimate the
required AEA dosages for various SCC mixtures based on the concept of
equivalent mortar air content.
d. The measured concrete air contents were within [+ or -]1.0% of
the design concrete air contents. The AEA dosages for achieving a target
concrete air content increased with lower W/B ratio and greater RHA
content due to the increases in binder content and surface area, and
HRWR dosage.
e. The estimated and actual AEA dosages for different SCC mixtures
were strongly correlated. Hence, the AEA dosage needed for the target
air content of SCC can be determined from the AEA dosage for the
equivalent air content of its mortar phase.
f. The technique demonstrated for determining the AEA dosage of SCC
can also be applied to the other types of concrete when the concept of
equivalent mortar air content is valid.
g. The technique presented for deciding the AEA dosage of concrete
is quick and simple. It is also cost-effective due to the minimum loss
of materials and labor.
doi: 10.3846/13923730.2011.589225
Acknowledgements
The authors express sincere gratitude to BASF Construction
Chemicals Canada Ltd. and Renewable Energy Generation Inc. for supplying
chemical admixtures and rice husk ash, respectively. The authors are
also grateful to Lafarge North America Inc. for the supply of cement.
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Md. Safiuddin (1), Jeffrey S. West (2), Khaled A. Soudki (3)
Department of Civil and Environmental Engineering, Faculty of
Engineering, University of Waterloo, 200 University Avenue West,
Waterloo, Ontario, Canada N2L 3G1
E-mails: (1) msafiudd@engmail.uwaterloo.ca (corresponding author);
(2) jswest@civmail.uwaterloo.ca; (3) soudki@civmail.uwaterloo.ca
Received 31 Jan. 2010; accepted 07 Oct. 2010
Md. SAFIUDDIN. Post-doctoral Fellow in the Department of Civil and
Environmental Engineering at the University of Waterloo, Ontario,
Canada. He is a member of American Society of Civil Engineers, American
Concrete Institute, and Bangladesh Environmental Network. Also, he is a
lifetime fellow of the Institution of Engineers, Bangladesh. His
research interests include concrete constituent materials, lightweight
concrete, high strength and high performance concretes,
self-consolidating concrete, green concrete and rehabilitation of
concrete structures.
Jeffrey S. WEST. Associate Professor in the Department of Civil and
Environmental Engineering at the University of Waterloo, Ontario,
Canada. His research interests include cement-based materials,
sustainability of concrete construction, composite bridges, and
assessment and repair of existing structures. Dr. West is the chair of
American Concrete Institute (ACI) Committee 224 (Cracking), and a member
of ACI Committees 130 (Sustainability), 222 (Corrosion of Metals) and
437 (Strength Evaluation of Existing Structures).
Khaled A. SOUDKI. Professor and the Canada Research Chair
(Innovative Structural Rehabilitation) in the Department of Civil and
Environmental Engineering at the University of Waterloo, Ontario,
Canada. His research interests include corrosion, durability performance
of advanced materials, structural health monitoring, and rehabilitation
of concrete structures using FRP composites. He is a member of American
Concrete Institute (ACI) Committees 440 (FRP Reinforcement), 222
(Corrosion of Metals) and 546 (Repair).
Table 1. Physical properties of constituent materials
Material Properties
Coarse Maximum size: 19 mm; fineness
aggregate (CA) modulus: 6.78; mass passing 75-[micro]m
dry sieve: 0.8%; void content: 37%;
saturated surface-dry relative density:
2.71; absorption: 1.5%; moisture content:
0.1%
Fine Maximum size: 4.75 mm; fineness
aggregate (FA) modulus: 2.74; mass passing 75-[micro]m
dry sieve: 1.8%; void content: 28%;
saturated surface-dry relative density:
2.62; absorption: 1.0%; moisture content:
0.1%
Cement (C) Relative density: 3.16; mass passing
45-[micro]m wet sieve: 91.5%; mass passing
75-[micro]m dry sieve: 99.1%; Blaine specific
surface area: 412 [m.sup.2]/kg; autoclave
expansion: 0.11%
Rice husk Relative density: 2.07; Blaine specific
ash (RHA) surface area: 2326 [m.sup.2]/kg; accelerated
pozzolanic activity index: 122.4%
Water (W) Density: 997.28 kg/m3; total solids:
430 mg/l
High-range water Relative density: 1.07; solid content:
reducer (HRWR) 41%
Air-entraining Relative density: 1.01; solid content:
admixture (AEA) 13%
Table 2. Chemical compositions of cement and RHA
Chemical component Mass content (%)
Cement RHA
Silicon dioxide or silica (Si[O.sub.2]) 19.7 93.6
Aluminum oxide or alumina ([Al.sub.2][O.sub.3]) 5.1 0.02
Iron oxide ([Fe.sub.2][O.sub.3]) 2.5 0.80
Calcium oxide or lime (CaO) 62.3 0.38
Magnesium oxide or magnesia (MgO) 3.3 0.34
Sulfur trioxide or sulfuric anhydrite (S[O.sub.3]) 2.9 --
Sodium oxide ([Na.sub.2]O) -- 0.05
Potassium oxide ([K.sub.2]O) -- 1.26
Equivalent alkalis ([Na.sub.2]O + 0.658 [K.sub.2]O) 0.72 0.88
Titanium oxide (Ti[O.sub.2]) -- 0.01
Phosphorous oxide ([P.sub.2][O.sub.5]) -- 0.58
Manganese oxide (MnO) -- 0.14
Chromium oxide ([Cr.sub.2][O.sub.3]) -- 0.01
Vanadium oxide ([V.sub.2][O.sub.5]) -- < 0.01
Free lime (FCaO) 1.1 --
Sulfur (S) -- < 0.01
Carbon (C) -- 0.15
Others:
Loss on ignition (LOI) 2.7 1.9
Insoluble residue 0.46 --
Table 3. Mixture proportions of various concretes (volume: 1 [m.sup.3])
Concrete W/B DAC CA FA C
type ratio (%) (kg) (kg) (kg)
C30R0A6 0.30 6 846.3 842.2 492.7
C30R15A6 0.30 6 829.9 825.8 418.8
C30R20A6 0.30 6 824.4 820.3 394.2
C35R0A6 0.35 6 876.1 871.8 422.3
C35R0A4 0.35 4 902.7 898.3 422.3
C35R0A8 0.35 8 849.4 845.2 422.3
C35R5A6 0.35 6 871.4 867.1 401.2
C35R10A6 0.35 6 866.7 862.4 380.1
C35R15A6 0.35 6 862.0 857.8 359.0
C35R15A4 0.35 4 888.6 884.2 359.0
C35R15A8 0.35 8 835.3 831.2 359.0
C35R20A6 0.35 6 857.3 853.1 337.8
C35R20A4 0.35 4 883.9 879.5 337.8
C35R20A8 0.35 8 830.6 826.5 337.8
C35R25A6 0.35 6 852.6 848.4 316.7
C35R30A6 0.35 6 847.9 843.7 295.6
C40R0A6 0.40 6 898.4 894.0 369.5
C40R15A6 0.40 6 886.0 881.7 314.1
C40R20A6 0.40 6 881.9 877.6 295.6
C50R0A6 0.50 6 928.3 923.7 296.8
Concrete RHA W HRWR dosage
type (% B) (kg) (kg) (% B)
C30R0A6 0 0 147.8 0.875
C30R15A6 15 73.9 147.8 1.75
C30R20A6 20 98.5 147.8 2.10
C35R0A6 0 0 147.8 0.70
C35R0A4 0 0 147.8 0.70
C35R0A8 0 0 147.8 0.70
C35R5A6 5 21.1 147.8 0.875
C35R10A6 10 42.2 147.8 1.05
C35R15A6 15 63.3 147.8 1.40
C35R15A4 15 63.3 147.8 1.40
C35R15A8 15 63.3 147.8 1.40
C35R20A6 20 84.5 147.8 1.75
C35R20A4 20 84.5 147.8 1.75
C35R20A8 20 84.5 147.8 1.75
C35R25A6 25 105.6 147.8 2.10
C35R30A6 30 126.7 147.8 2.45
C40R0A6 0 0 147.8 0.60
C40R15A6 15 55.4 147.8 1.00
C40R20A6 20 73.9 147.8 1.20
C50R0A6 0 0 148.4 0.50
Note: B = C + RHA; DAC = design air content
Table 4. Mixture proportions of various mortars (volume: 3 1)
Mortar type Parent concrete FA C RHA
(kg) (kg) (kg)
M30R0A6 C30R0A6 4.030 2.358 0
M30R15A6 C30R15A6 3.914 1.985 0.350
M30R20A6 C30R20A6 3.875 1.862 0.465
M35R0A6 C35R0A6 4.246 2.057 0
M35R0A4 C35R0A4 4.305 2.024 0
M35R0A8 C35R0A8 4.186 2.092 0
M35R5A6 C35R5A6 4.212 1.949 0.102
M35R10A6 C35R10A6 4.178 1.841 0.204
M35R15A6 C35R15A6 4.143 1.734 0.306
M35R15A4 C35R15A4 4.202 1.706 0.301
M35R15A8 C35R15A8 4.082 1.763 0.311
M35R20A6 C35R20A6 4.109 1.627 0.407
M35R20A4 C35R20A4 4.169 1.601 0.401
M35R20A8 C35R20A8 4.048 1.654 0.414
M35R25A6 C35R25A6 4.075 1.521 0.507
M35R30A6 C35R30A6 4.041 1.416 0.607
M40R0A6 C40R0A6 4.414 1.824 0
M40R15A6 C40R15A6 4.321 1.539 0.271
M40R20A6 C40R20A6 4.290 1.445 0.361
M50R0A6 C50R0A6 4.646 1.493 0
Mortar type W HRWR dosage AEA dosage
(kg) (% B) (ml)
M30R0A6 0.707 1.25 1.0-4.0
M30R15A6 0.701 2.50 1.0-4.0
M30R20A6 0.698 3.00 1.0-4.0
M35R0A6 0.720 1.00 1.0-4.0
M35R0A4 0.708 1.00 1.0-4.0
M35R0A8 0.732 1.00 1.0-4.0
M35R5A6 0.718 1.25 1.0-4.0
M35R10A6 0.716 1.50 1.0-4.0
M35R15A6 0.714 2.00 1.0-4.0
M35R15A4 0.702 2.00 1.0-4.0
M35R15A8 0.726 2.00 1.0-4.0
M35R20A6 0.712 2.50 1.0-4.0
M35R20A4 0.701 2.50 1.0-4.0
M35R20A8 0.724 2.50 1.0-4.0
M35R25A6 0.710 3.00 1.0-4.0
M35R30A6 0.708 3.50 1.0-4.0
M40R0A6 0.730 0.75 1.0-4.0
M40R15A6 0.724 1.25 1.0-4.0
M40R20A6 0.723 1.50 1.0-4.0
M50R0A6 0.746 0.50 0.5-2.0
Note: B = C + RHA
Table 5. AEA dosages and air content for various concrete mixtures
Concrete type W/B ratio RHA content Slump flow
(% B) (mm)
C30R0A6 0.30 0 710
C30R15A6 0.30 15 735
C30R20A6 0.30 20 770
C35R0A6 0.35 0 690
C35R0A4 0.35 0 700
C35R0A8 0.35 0 670
C35R5A6 0.35 5 700
C35R10A6 0.35 10 710
C35R15A6 0.35 15 720
C35R15A4 0.35 15 720
C35R15A8 0.35 15 720
C35R20A6 0.35 20 710
C35R20A4 0.35 20 690
C35R20A8 0.35 20 695
C35R25A6 0.35 25 740
C35R30A6 0.35 30 750
C40R0A6 0.40 0 665
C40R15A6 0.40 15 680
C40R20A6 0.40 20 675
C50R0A6 0.50 0 605
Concrete type AEA dosage (% B) Air content (%)
Estimated Actual Design Actual
C30R0A6 0.030 0.026 6 5.7
C30R15A6 0.045 0.047 6 5.3
C30R20A6 0.052 0.056 6 5.7
C35R0A6 0.022 0.020 6 5.3
C35R0A4 0.015 0.016 4 4.3
C35R0A8 0.031 0.026 8 8.1
C35R5A6 0.026 0.025 6 5.5
C35R10A6 0.030 0.035 6 5.1
C35R15A6 0.043 0.045 6 5.1
C35R15A4 0.023 0.031 4 4.2
C35R15A8 0.072 0.072 8 8.0
C35R20A6 0.051 0.054 6 5.0
C35R20A4 0.027 0.036 4 4.3
C35R20A8 0.078 0.083 8 8.6
C35R25A6 0.060 0.070 6 5.6
C35R30A6 0.070 0.080 6 5.2
C40R0A6 0.013 0.011 6 6.1
C40R15A6 0.041 0.040 6 5.2
C40R20A6 0.049 0.051 6 5.3
C50R0A6 0.008 0.006 6 5.2
Note: B = C + RHA
