potentials of particles from crushed abakaliki pyroclastic ...€¦ · (pcc) in parts of abakaliki...
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FUNAI Journal of Science and Technology
3 (2), 2017, 120-133
POTENTIALS OF PARTICLES FROM CRUSHED ABAKALIKI PYROCLASTIC
ROCKS TO REPLACE SAND IN CONCRETE WORKS
Okechukwu Pius Aghamelu
Department of Physics/Geology/Geophysics, Federal University Ndufu Alike-Ikwo, Nigeria
(Received 20 December 2016; Revised 19 July 2017; Accepted:21 July, 2017)
Abstract
Particles derived from crushed pyroclastic rock (CPR) were investigated to determine the
suitability of the material as fine aggregate in general purpose Portland cement concrete
(PCC) in parts of Abakaliki area of Ebonyi State, southeastern Nigeria. Particle size
distribution, specific gravity (SG), and water absorption (Wa) were determined on sand
deposit (commonly used for concrete making within the study area) and CPR that passed 9.5
mm British Standard test sieve opening. The sieve opening (9.5 mm) represents the upper
limit of diameters of sand-sized particles in soils. Coarse aggregate and type IV (normal
hardening) Portland cement were mixed with the two materials to form concrete specimens,
which were subjected to compressive strength tests at periods of 14 and 28 days of curing. The
ratios of sand to CPR were 1:0, 4:1, 1:1, 1:4 and 0:1. Tests results indicate that the CPR have
considerable amount of micro-fines (15%), relatively low Wa (2.52%) and appreciable SG
(2.65). The strength of the PCC, at 14 days curing period, increased from 37 N/mm2 to 40
N/mm2 with addition of 25% CPR but dropped to 29 N/mm
2 when increased to 100%. Study
indicates that mixing sand with about 25% CPR and longer curing period (≥ 28 days), rather
than total sand replacement, would likely yield PCC with generally good performance in service.
Keywords: Abakaliki pyroclastics; Crushed rock particles; Geotechnical properties; Sand;
Portland cement concrete.
1. Introduction
Portland cement concrete (PCC) is an
artificial engineering material made from a
mixture of Portland cement, water, fine
and coarse aggregates. The fine
aggregate is the material passing 4.75 mm
(#4) test sieve and retained in 75µm (#200)
test sieve, and could be natural
or manufactured from crushing of rocks.
Concrete is about the only major building
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material that can be delivered to the
construction site in plastic state, hence, it
can be moulded to virtually any form or
shape. Many types of concrete such as
high performance concrete, self
compacting concrete, reinforced concrete
and green concrete (Okamura and Ouchi,
2003), are being used today to construct a
wide variety of structures, such as
highways, bridges, dams, large buildings,
airport runways, irrigation structures,
pavements, silos and farm buildings. The
desirable property of concrete mixtures,
especially its ability to be moulded to any
shape, high demand in numerous
construction projects and the need for more
infrastructural development to cater for an
increasing population have necessitated
increased demand for concrete and its
constituents in many parts of the world.
In a bid to meet the high demand for
concrete and its composite materials in the
Abakaliki Metropolis, Southeastern
Nigeria (Figure 1), and due to inadequate
supply and high cost of
construction sand within the metropolis,
crushed pyroclastic rock particles (CPR), a
product of rock quarrying with particles
that range from fine aggregate to micro
fines (i.e., particles passing 75 µm or #200
sieve), is currently being used by local
builders and engineers in the Abakaliki area
as a substitute for sand including fine
aggregate, especially in concrete mixes. A
number of collapsed building cases have
been recorded in the areas where this
material has been commonly used in PCC
(Aghamelu et al., 2011; Aghamelu and
Okogbue, 2011).
No documented or published data or
information exists on the appropriateness of
the CPR as a replacement or a constituent
of PCC mixtures. Aghamelu and
Okogbue (2013) had, however, noted that
the pyroclastic rock could only serve
marginally well as coarse aggregate
source in most types of concrete.
Previous researchers (Wong et al., 2001)
have listed the factors that influence the
workability and performance of concrete
to include the properties and amount of
the cement, grading, shape, angularity and
surface texture of the fine and coarse
aggregate. It has been noted that
manufactured fine aggregate processed
from crushed stone generally contain a
greater quantity of fines than natural sands
and often mask their good workability with
low slump test results (Daniel, 2006).
Earlier works (American Concrete
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Institute, 1990; British Standard
Institute, 1881, 1993; American Society for
Testing and Materials, C143, 1994) have
presented and described in details some
basic test procedures for assessing
concrete materials and concrete mixes.
This study, therefore, attempts to use
standard laboratory tests to investigate the
qualities of crushed rock particles from the
Abakaliki Pyroclastics and the PCC in
which it serves as fine aggregate.
Highlights on the suitability of the CPR
as fine aggregate for concrete are mainly
from the viewpoint of the analysis
conducted on both the raw crushed rock
particles and concrete sample.
Figure 1. Map of Southeastern Nigeria showing the position of Abakaliki, Ebonyi State and other surrounding states
1.1 Production of crushed aggregates in
the Abakaliki area of Ebonyi State
Rock quarrying and crushing industry
thrives in the Abakaliki area. This industry
is sustained by the abundance of pyroclastics
and other minor intrusives within the area.
The pyroclastic rocks are among the
volcanic rock suite that was produced by
explosive activity within the Asu River
Group in the Abakaliki area. The rocks are
best exposed in the area within a 12 km
radius of the Abakaliki Metropolis;
specifically in the areas around the
Government House, Onwe Road, Gulf
Course, near the Federal Teaching Hospital,
Abakaliki (FETHA) II, Juju Hill, Nkaliki,
Onyikwa, Aghameghu, Aguogboriga,
Sharon and Amike Abba. The Abakaliki
Pyroclastics consist of a sequence of mafic
lavas, pyroclastic flows, tuffs, agglomerates
and amygdaloidal lavas of basaltic
composition and alkaline in nature
(Aghamelu and Okogbue, 2013; Ofoegbu
and Amajor, 1987; Obiora and Umeji,
1995). At the Umuoghara crushers’ cluster,
near Abakaliki metropolis, about 10,000
metric tons of different sized coarse
aggregates of pyroclastic rocks are
produced. The coarse aggregate sets are
being supplied to contractors and builders
mainly for construction of major projects
(especially roads and concrete for
buildings) within and around the
Southeastern Nigeria. Pyroclastic rock dust
(PRD), a trade name for the by-product of
the massive pyroclastic rock quarrying
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activity, is considered almost a waste
product owing to large tonnage produced
and its very low commercial value. While
sand, which conventionally serves as fine
aggregates in PCC mixes in the area is sold
at the rate of N 25, 500 (fifteen thousand
Naira, about seventy US dollars) per metric
ton, the PRD is supplied at a price of N 7,
000 (three thousand naira, about twenty US
dollars) or less per metric ton to local
builders and contractors. These local
builders and contractors, due to mainly
economic reasons, commonly use PRD
instead of sand as fills or fine aggregates in
concrete (both asphalt and Portland cement
varieties) or as mortars and plasters, with
little or no effort to ascertain its field
performance or suitability in those projects.
2. Materials and methods
2.1 Material sampling
The CPR sample was collected from the
Umuoghara crushers’ cluster near Abakaliki
Metropolis, while the sand sample was
river sand deposit from Emene River,
near Oye market in Enugu, southeastern
Nigeria, commonly sourced for concrete and
other construction projects within the area.
2.2 Particle Size Distribution Analysis
The river sand deposit and CPR samples
were both subjected to mechanical (particle
size) analysis. The analyses on both
materials were on particles sizes that
passed the 9.5 mm (#3/8) British Standard
test sieve (which represents the upper limit
of the diameters of sand-sized particles in
soils), and was in accordance with BSI 1377
(1990).
2.3 Specific Gravity and Water Absorption
Tests
Both specific (apparent) gravity and water
absorption determinations in this study
were carried out only on the PRD, and
the test was in accordance with standard
procedures (American Society for Testing
and Materials, C128, 1990; American
Society for Testing and Materials, C117,
1995). About 2 kg of the fine aggregate
fraction, size passing 4.75 mm (#4) test
sieve was subjected to apparent specific
gravity test procedure, using a pycnometer
test bottle. Water bathing was, however,
achieved with a basin filled with distilled
water at room temperature.
2.4 Compressive Strength Test
The compressive strength test was
conducted according to ASTM C39
(1999), and the concrete mixing was in
accordance with ASTM C192 (2000). In
general, compressive
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strength was tested at periods of 14 and
28 days on ten 4 in. × 8-in. cylinder
moulded samples. Before testing, the
specimens were cured in a moisture room
at 100 percent humidity, as described in an
earlier work (Quiroga and Fowler, 2004).
The percentages by volume of the various
ingredients used are shown in Figure 2. The
ratios of sand to CPR were 1:0, 4:1, 1:1, 1:4
and 0:1, that is, 100 to 0 %, 75 to 25 %, 50 to
50 %, 25 to 75 % and 0 to 100 %,
respectively. Water/cement ratio was
calculated as the volume of water divided
by the volume of cement.
Figure 2. Proportions, by percentage volume, of ingredients used in the PCC mix
3. Results and discussion
The concrete specimens were from PCC
mixes that have varied percentages by
weight of sand and CPR as fine aggregate
component. The cement was the Type IV
(normal hardening) Portland cement.
Crushed pyroclastics that passed through
25.0 mm (1 in.) sieve, but were retained in
4.75mm (#4) sieve were utilized as the
coarse aggregate.
3.1 Particle size distribution
Results of mechanical analysis on the
particles derived from crushed pyroclastic
rock and natural sand are summarized in
Table 1. The gradation curve of the CPR is
shown in Figure 3. Analysis indicates that
the crushed rock particles contained
significantly higher amount of fine
particles than the experimental sand. It has
been noted that manufactured fine
aggregates from crushed rocks yield greater
amount of fines than natural sands (Daniel,
2006). On the basis of the calculated
fineness modulus in Table 2, the CPR would
classify as fine sand (see Table 3) or poorly
graded sand (SP), according to Unified Soil
Classification System.
Grading or particle size distribution has been
reported as one of the major factors that
affect significantly some characteristics of
concrete like packing density, voids
content, and, consequently, workability,
segregation, durability of concrete
(Scanlon, 1994; Quiroga and Fowler,
2004). Wong et al. (2001) had observed
that the use of fine aggregates with high
amount of micro-fines (percent passing
through No. 200 sieve) requires that more
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water be added to achieve the workability
that a coarser sand would provide. As shown
in Table 4 and Figure 3, the CPR is well
within the fine aggregate grading limits
given by ASTM C33 (2003)
and ACI (2007); it is only the quantities of
particles less than 0.3 mm and 0.15 mm,
that is, passing #50 and #100 sieves, that are
above the required specification.
Table 1. Results of sieve analysis on the fine
aggregates used in this study
Sieve size
(mm)
Sieve
No.
Natural
sand*
Crushed rock
particles*
9.5 3/8 100 100
4.75 4 98 91
2.36 8 85 81
1.18 16 66 69
0.6 30 31 53
0.3 50 6 39
0.15 100 1 25
*Percentage passing (%)
Figure 3. Typical grading chart for fine aggregates (Modified from American Society for Testing and Materials, C33, 2003; American Concrete Institute, 2007)
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Table 2. Calculation of fineness modulus (FM) of crushed rock particles
Sieve No. Weight retained (%)
Individual Cumulative Cumulative
percent Retained 4 90 90 9
8 100 190 19
16 120 310 31
30 160 470 47
50 140 610 61
100 140 750 75
Pan 250 - -
Total weight 1000 - 242
FM = 242/100 = 2.42
Table 3. Fineness modulus (FM) ranges for fine aggregates
FM* Designation* Crushed rock
particles*
2.3 – 2.59 Fine sand 2.42
2.6 - 2.89 Medium sand -
2.9 – 3.1 Coarse sand -
*data from Army Institute for Professional Development (1992)
Table 4. Crushed rock particles compared with fine aggregate grading limits
Sieve size (mm) Sieve No. Fines percentage
passing*
Crushed rock
particles
Remarks
9.5 3/8 100 100 The crushed rock
particles considerably
meet the grading
limits, with only
particles less than the
#50 sieve failing
outside the limits.
4.75 4 95 – 100 91
2.36 8 80 – 100 81
1.18 16 50 – 85 69
0.6 30 25 – 60 53
0.3 50 5 – 30 39
0.15 100 0 – 10 25
*data from ASTM C33 (2003)
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The fact that CPR meets grading limits
could suggest that the material would be
suitable as fine aggregate for PCC. A
comparison of the amount of micro-fines in
the material with the amount of allowed
micro-fines limits in fine aggregates
from some parts of the world is
presented in Table 5, and it indicates that the
material compares well with the allowed
micro fines limits from some parts of the
world. The fineness modulus (FM) of the
CPR also falls within the acceptable limits.
The FM of good fine aggregate should fall
between 2.3 and 3.1 (American Society for
Testing and Materials, C33, 2003).
Reduction in the workability and
strength of concrete made with this
material is to be expected with an increase
in quantity (Wong et al., 2001). Aghamelu
and Okogbue (2013) had noted presence of
clay minerals and secondary carbonates as
lithic fragments in the thin section
specimens of the Abakaliki pyroclastics.
Deterioration caused by weathering of these
minerals could lower the quality and
suitability of the material and the PCC it is
made of over time.
Table 5. Comparison of allowable micro-fines limits from different parts of world
Country Micro-fines allowed (%) Sieve (µm) Fine aggregate type
United States 5 – 7 75 -
Spain 6 63 Natural sand
15 63 Crushed sand
England 15 63 -
India 15 – 20 - -
Australia 25 – 20 - -
France 12 – 18 63 -
Nigeria 15* 75 Crushed rock particle
*data from this study, the rest from Quiroga and Fowler (2004) -unavailable
3.2 Specific gravity and water absorption
The results of specific gravity (SG) and
water absorption (Wa) tests on the CPR,
alongside SG and Wa data of natural and fine
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aggregates from some major rock types, are
presented in Table 6. Although specific
gravity SG is not necessarily related to
aggregate behaviour (Quiroga and Fowler,
2004), it has been observed that materials that
have somewhat low SG may display poor
durability as construction materials. This is
because the SG values of most natural
materials, rock or soil, reflect the average
weight of the predominant mineral(s) or
elements they contain (Krynine and Judd,
1957; Eze, 1997).
A comparison of the SG values of fine
aggregates produced from some common rock
types are presented in Table 6. The table
indicates that basic rocks (eg diabase and
basalt) produced fine aggregates with higher
SG values than acidic and alkaline rocks,
granite and Abakaliki pyroclastics,
respectively. Mineralogically, basic rocks
contained higher amount of
heavy minerals than acidic and alkaline
rocks. Most stable and durable minerals
and aggregates have their SG values greater
or equal to 2.65 and their Wa significantly
lower than 2.5 %. High Wa is most often
caused by high content of weak micro-
fines and minerals (Krynine and Judd,
1957). Previous researches (Quiroga and
Fowler, 2004; Kronlof, 1994) indicate that
fine aggregates with very low Wa generally
develop higher strength bonds but produce
less durable mortars than those with slightly
higher absorption.
Glanville et al. (1947) and Galloway
(1994) had noted that a general increase in
fine aggregate/coarse aggregate ratio
generally increases the water content required
to produce a given workability in concrete.
Aggregates with high absorptive micro-fines
present a special case because, if they are
batched with a large unsatisfied absorption,
they can remove water from the final concrete
mixture and, hence, reduce workability (Wong
et al. 2001).
3.3 Compressive strength
Result of concrete compressive strength tests
on concrete specimens, made of varied ratios
of sand and CPR and different curing
periods, is graphically presented in Fig. 4. It
can be observed from the figure that the
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compressive strength of the PCC increased
from 37 N/mm2
to 40 N/mm2 with the
addition of 25 % CPR into the mix, at 14
days curing period. The
strength value, however, dropped to 40
N/mm2 and 37 N/mm
2 with the addition of 50
% and 75 % crushed rock particles,
respectively, at the same curing period. The
lowest strength values (29 N/mm2 and 30
N/mm2, for 14 and 28 days periods of
curing, respectively) were recorded when
sand was completely (100 %) replaced with
CPR. Longer period of curing (from 14 to
28 days), as shown in Fig. 4, however,
brought about slight increases in the
strength of the PCC samples (between 2 and
22 % increase in strength values). Possible
explanation to the decrease in strength (from
40 N/mm2
to 29 N/mm2, at 14 days of curing)
of the concrete with increased CPR (from 25
to 100 %) could be that blending to total
substitution of sand with the crushed rock
particles brought about an increase in the
amount of weak particles, especially in the
micro-fines fraction. Although, addition of
small amounts of the material improved the
strength, workability, and density for lean
concrete mixtures (Forster, 1994; Hudson,
1997, 1999), in excess micro-fines
constituent of the material produced the
reverse of these qualities in concrete.
Figure 4. Plot of compressive strength against percent crushed rock particles
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4. Summary and conclusions
This study subjected CPR from the Abakaliki
pyroclastics and the PCC samples made using
varying percentages of sand and the CPR to
laboratory analyses to determine the potentials
of the rock particles as fine aggregate for
concrete making. The following findings were
made;
1. Crushing of pyroclastic rock yielded
particles with very significant amount of
fine
particles. The micro-fines so yielded,
however, fall within the allowable limits in
fine aggregates used in some parts of the
world.
2. The CPR recorded relatively high specific
gravity (2.65), low water absorption (2.52
%), and micro-fines that fall within allowable
limits, suggesting fair to good suitability as
fine aggregate for PCC. In excess quantity,
however, the CPR may cause a general
increase in the water content required to
produce good workability in concrete.
3. Strength analysis on the concrete specimens
made with the CPR, however, indicates that
the compressive strength reduced drastically
with 100 % increase. This suggests that a total
replacement of sand with CPR may have
introduced an appreciable amount of weak
particles, coming especially from the micro-
fine fraction, into the concrete mixture
resulting in low workability and strength.
4. This study reveals that blending sand
with about 25 % crushed pyroclastic rock
particles and longer period of curing (≥ 28
days) would likely yield PCC with good
performance in service. Any other mix
design, involving CPR, may be used but with
caution.
Acknowledgements
Babadiya Gbadebo of the Material laboratory
of Ebonyi State Ministry of Works and
Housing, Abakaliki, and Joseph Nna, formerly
of the Department of Geology, Ebonyi State
University, Abakaliki, are warmly appreciated
for assisting in the sampling and laboratory
analyses.
References
Aghamelu, O. P. and Okogbue, C O. (2011).
Geotechnical assessment of road failures
in the Abakaliki area, southeastern
Nigeria. International Journal of Civil
and Environmental Engineering.
11(2):12-24.
Aghamelu, O. P., Nnabo, P. N. and Ezeh, H.
N. (2011). Geotechnical and
environmental problems related to
shales in the Abakaliki area,
Potentials of particles from crushed abakaliki pyroclastic rocks... Aghamelu
FUNAI Journal of Science and Technology, 3(2), 2017 Page 131
southeastern Nigeria. African Journal
of Environmental Science and
Technology. 4(12):80-88.
Aghamelu, O. P. and Okogbue, C. O. (2013).
Some geological considerations and
durability analysis on the use of
crushed pyroclastics from Abakaliki
(southeastern Nigeria) as concrete
aggregate. Geotechnical and Geological
Engineering. (2):699-711.
American Concrete Institute (ACI). (1990)
Cement and concrete terminology. ACI
116R, ACI Manual of Concrete Practice,
Part 1. Washington D. C.
American Concrete Institute (ACI). (2007).
Aggregates for concrete. ACI Education
Bulletin E1-07. Washington D. C.
American Society for Testing and Materials
(ASTM). (1990). Standard test method
for specific gravity and absorption of
fine aggregate. Designation C 128.
American Society for Testing and
Materials, Philadelphia.
American Society for Testing and Materials
(ASTM). (1994). Standard test method
for slump hydraulic-cement concrete.
Designation C 143. American Society
for Testing and Materials, Philadelphia.
American Society for Testing and Materials
(ASTM). (1995). Standard test method
for materials finer than 75 µm (No. 200)
sieve in mineral aggregates by washing.
Designation C 117. American Society
for Testing and Materials, Philadelphia.
American Society for Testing and Materials
(ASTM). (1999) Standard test method
for compressive strength of cylindrical
concrete specimens. Designation C 39. American Society for Testing and Materials, Philadelphia.
American Society for Testing and Materials
(ASTM). (2000). Standard practice for
making and curing concrete tests
specimens in the laboratory.
Designation C 192. American Society
for Testing and Materials, Philadelphia.
American Society for Testing and Materials
(ASTM). (2003). Standard specification
for concrete aggregates. Designation
C33. American Society for Testing and
Materials, Philadelphia.
Army Institute for Professional Development
(AIPD). (1992). Concrete engineering,
A Edition. Subcourse No. EN 5466.
Washington D. C.
British Standard Institution (BSI). (1990).
Methods of testing soil for civil
engineering purposes. BS 1377. British
Standard Institution, London.
British Standard Institute (BSI). (1993).
Method for determination of compacting
factor for testing concrete. BS 1881,
Part 103. British Standard Institution,
London.
Potentials of particles from crushed abakaliki pyroclastic rocks... Aghamelu
FUNAI Journal of Science and Technology, 3(2), 2017 Page 132
Eze, E. O. (1997). Geotechnical assessment of
some charnockites from Nigeria as
construction materials. Quarterly Journal
of Engineering Geology. 30:231-236.
Daniel, D. G. (2006). Factors influencing
concrete workability. In: Lamond, J. F.
and Pielert, J. H. (Editors). Significance
of tests and properties of concrete
and concrete-making materials.
STP169D. American Society for Testing
and Materials, Philadelphia, 59-64.
Forster, S. W. (1994). Soundness,
deleterious substances, and coatings.
Special Technical Publication No.
169C. American Society for Testing
and Materials, Philadelphia. 411-420.
Glanville, W. R., Collins, A. R. and Mathews,
D. D. (1947). The grading of aggregate
and workability of concrete. Road
Research Technical Paper 5. American
Society for Testing and Materials,
Philadelphia.
Galloway, J. E. (1994). Grading, shape, and
surface properties of aggregates. Special
Technical Publication No. 169C.
American Society for Testing and
Materials, Philadelphia. 401-410.
Hudson, B. P. (1997). Manufactured sand for
concrete. Proceedings of the 5th Annual
International Center for Aggregates
Research Symposium, Austin.
Hudson, B. P. (1999). Modification to the fine
aggregate angularity test. Proceedings of
the 7th
Annual International Center for
Aggregates Research Symposium,
Austin.
Kronlof, A. (1994). Effect of very fine
aggregate on concrete strength.
Materials and Structures. 27:15-25.
Krynine, D. P. and Judd, W. R. (1957).
Principles of engineering geology and
geotechnics. McGraw-Hill, New York.
Obiora, S. C. and Umeji, A. C. (1995).
Alkaline intrusive and extrusive rocks
from areas from west of the Anyim
River, Southeastern Benue Trough. J in
Geol. 1995:31(1):9-19.
Ofoegbu, C. O. and Amajor, L. C. (1987). A
geochemical comparison of the
pyroclastic rocks from Abakaliki and
Ezillo, southern Benue Trough, Nigeria.
Journal of Mining and Geology.
23(1&2):45-52.
Okamura, H. and Ouchi, M. (2003). Self-
compacting concrete. Journal of
Advances in Concrete Technology.
1(1):5-15.
Quiroga, P. N. and Fowler, D. W. (2004). The
effects of aggregates characteristics on
the performance of Portland cement
concrete. Technical Report No. ICAR
Potentials of particles from crushed abakaliki pyroclastic rocks... Aghamelu
FUNAI Journal of Science and Technology, 3(2), 2017 Page 133
104-IF. International Center for
Aggregate Research, The Texas
University, Austin.
Scanlon, J. M. (1994). Factors influencing
concrete workability. In: Klieger, P. and
Lamond, J. F. (Editors). Significance of
tests properties of concrete and
concrete-making. STP 169C.
American Society for Testing and
Materials, Philadelphia.
Wong, G. S., Alexander, A. M., Haskins,
R., Poole, T. S., Malone, P. G. and
Wakeley, L. (2001). Portland cement
concrete rheology and workability; final
report. Report No. FHWA-RD-00-025.
United States Department of
Transportation, Federal Highway
Administration, Georgetown Pike.