World Journal of Engineering and Technology, 2014, 2, 42-47
Published Online September 2014 in SciRes. http://www.scirp.org/journal/wjet
How to cite this paper: Yang, M.-J., Wang, H.-Y. and Liang, C.-F. (2014) Effects on Strengths of Cement Mortar When Using
Incinerator Bottom Ash as Fine Aggregate. World Journal of Engineering and Technology, 2, 42-47.
Effects on Strengths of Cement Mortar When
Using Incinerator Bottom Ash as Fine
Min-Jen Yang, Hong-Yu Wang, Chou-Fu Liang*
Department of Civil Engineering, National Pingtung University of Science and Technology, Taiwan
Received Ju ly 2014
The main purpose of this paper is to study the feasibility of using the Incinerator bottom ash fine
aggregate to replace natural fine aggregate in the cement mortar products. The research adopts
high cement content mortar to conduct the experiment, in which the weight ratio of cement/ag-
gregate is 1/2. The experiment uses Incinerator bottom ash fine aggregates, which passes through
#16 sieve , and natural sand of the same size as the aggregate, and separates mortar specimens in-
to two main categories based on different W/C ratio. Moreover, different proportions of furnace
slag and F-class are used to replace a portion of cement so as to explore the influence on strength
of Incinerator bottom ash aggregates mo rt ar by adding the two admixtures. The study shows that,
based on the 1:2 cement/aggregate weight ratio, Incinerator bottom ash fine aggre-gates mortar,
unit weight around 1.8 g/cm3, is 20% lighter natural fine aggregate mortar, unit weight around 2.2
g/cm3. The Incinerator bottom ash fine aggregates mortar can only reach 60%-70% the compres-
sive strength of natural fine aggregates mortar. Direct tensile strength and flexural tensile
strength tests are 15% and 30% of compressive strength respectively, due to the irregular strength
development, which does not follow general concepts, such as low W/C ratio and mineral admix-
tures will not necessarily help in strength development in Incinerator bottom ash fine aggregates
Incinerator Bottom Ash Aggreg ra te, Mineral Admixture, Cement Mortar
Incinerator bottom ash (abbreviated as IBA in the following of this paper) aggregates mainly come from the
solid remains of refuse incineration plant, by going through certain leaching and sieving processes. The main
purpose of this paper is to study the feasibility of using the IBA fine aggregate to replace natural fine aggregate
in the cement mortar products. The research intend to use recycled waste and transform the “waste” into “re-
sources”, and put them into construction materials to meet the concepts of “green construction”, “environment
protection” and “recycling resource” . Ho wever, i n order to fur ther und erstand the applicatio n of IBA aggr e-
gates based cement concrete prod uct, the study also discusses the effects of IBA fine aggregates on the strength
M.-J. Yang et al.
of ce ment mort ar and the stre ngth var iat ions whe n usi ng fly ash a nd b last fur nace sla g to pa rtially substitute ce-
ment . The stud y hopef ull y co uld pr ovid e via ble dir ection for futur e stud y of u sing I BA ag grega te s in ce ment
2. Research Purpose
For the time being, in Taiwan, the IBA aggregates are often used in permeable recycled concrete with lean con-
crete proportions. However, the low strength of permeable concrete mainly comes from low cement contains,
which cannot clea rly show the impact IBA aggregates on the concrete strength  . I n per meable concrete the
cement weights around 1/8 of aggregate. To eliminate the effect of lean concrete on strength, the research adopts
high ceme nt co nt e nt mor tar to c o nduc t t he e xpe r i ment , i n w hic h the weight ratio o f cement/aggre gate is 1/2. The
experiment uses IBA fine aggregates, which passes through #16 sieve, and natural sand of the same size as the
aggregate, and separates mortar specimens into two main categories in which each contains 6 groups of speci-
men, based on different W/C ratio and mineral admixtures portions. The specimens consist of 5 × 5 × 5 cm cu-
bic blocks, Briquet pieces, and 4 × 4 × 16 cm rectangular bars and are used in performing compressive and ten-
sile strength measuring to discuss the basic properties of each group of cement mortar. Moreover, to comply
with economic and environme ntal principles, it adds different proportions of furnace slag and F-class fly ash to
replace a portion of cement so as to explore the influence on strength of IBA aggregates concrete by adding the
two admixtures .
3. Research Method
The experime nt uses I BA fine a ggregate s passin g throug h #16 sieve and natur al fine a ggrega tes with sa me siz e
as t he a ggre gate, a nd the ad mixtur e s ar e F-typ e fl y as h and blast furnace slag. Addi ng the t wo admixt ures is e x-
pected to increase the workability and strength of the mortar specimens. The experiment is divided into two
main groups based on W/C ratio. Each mai n group co ntains 6 subgroup s in which t he spec imens consi st of dif-
ferent percentage of IBA fine aggregates, fly ash, and furnace slag, so as to verify the effects of the ingredients
on the strength of the specimens. The proportions of mortar are as shown, by ratio of weight, in Table 1. The
test specimens are mainly divided into 12 groups, wherein the mortars, namely “Control 1” and “Control 2”,
contain 100% nature fine aggregate are as the controlled basis, the sub groups, namely gr oup A-J, use only IB A
fine a ggr egate s and di ffere nt po rti ons o f fly a sh and furnace slag partially replacing cement, so as to explore the
strength differences among the groups. The water cement ratio of the specimens are controlled by standard mor-
tar flow test, the mortar flow of each group falls between 100% - 150% to insure that no cement paste segrega-
tion occurs when casting the specimens.
4. Results and Discussion
4.1. Basic Physical Property Test of Incineration Bottom Ash
The test results of basic properties testing are shown in Table 2. As being expected, the IB A fine aggre gate s has
a higher water absorption capacity than natural fine aggregate, and its specific gravity and dry-rodded unit
weight are also lower than those of natural fine aggregate. For the bottom ash has a faster water absorption rate,
the 30 min. absorption rate, which is not a standard test, is mainly used as a reference in process of adding water
when mixing the cement mortar containing IBA fine aggregates. That can prevent higher absorption capacity of
IBA fine aggregates from affecting the designed water cement ratio during mixin g mortar.
4.2. Result Analysis
The material ages for each strength test are 7, 28 and 56 days. The tests performed are compressive, direct ten-
sile, and flexural tensile strengths of mortar specimens, which are to get a preliminary understanding of the in-
fluence of IBA fine aggregates and mineral admixture on strength of the mortars. The strength test result of each
specimen after 7, 28 and 56 days curing is sho wn in Table 3. In general, material age of 7 days has lower a nd
inconsistent co mpressive strength due to the incomplete hydration, so the 7-da y strength is only taken as refer-
ence. Unit weight of each specimen is shown in Table 4. When the ag gregate is replaced by IBA fine aggregates,
there is obvious difference on the unit weight, due to the lower specific gravity of IBA fine aggregates.
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Table 1. The ratio of Cement Mortar to material by weigh .
Specimen Group Wat er C emen t F ly As h Sla g IBA Fine Aggregates Nature Sand
Control 1 1.4 2 --- --- --- 4
Control 2 1.36 2 --- --- --- 4
A 1.4 2 --- --- 4 ---
B 1.36 2 --- --- 4 ---
C 1 .4 1 .8 0.2 --- 4 ---
D 1.4 1 .6 0 .4 --- 4 ---
E 1.36 1.8 0.2 --- 4 ---
F 1.36 1.6 0 .4 --- 4 ---
G 1.4 1 .8 --- 0.2 4 ---
H 1.4 1 .6 --- 0.4 4 ---
I 1.36 1.8 --- 0.2 4 ---
J 1.36 1.6 --- 0.4 4 ---
Table 2. The General Aggregate Test of the basic physical properties and the bottom ash properties.
Specific Gravity Abs o rptio n Capac i t y
(%) Dry-rodded unit weight
(kg/m 3) 30 min Absorp tion Rate
Natural fine aggregate 2.68 1.8 1616 -
IBA fine aggregates 2.2 9 .2 1125 4 .2
Table 3. The test result of the intensity of anti-press, anti-pull, and anti-bend.
Strength an d age
Spec i men Group
Comp res s ive Stren gth (kg/c m 2) Tensile Strength (kg/cm2) Flexural Strengt h (kg/cm2)
7 28 56 7 28 56 7 28 56
Control 1 232 .59 256 .69 384 .97 31.53 31.53 40. 53 58.614 6 7.02 7 7.249
Control 2 293 .96 390 .72 438 .66 31.07 34.82 40. 53 66.737 8 1.59 8 1.709
A 133.87 1 92.38 2 17.66 15. 71 19.79 24.46 36. 713 38. 82 46. 827
B 1 97 .35 209 .46 289 .05 21.47 22.02 21. 12 43.482 5 0.29 5 2.681
C 1 60 .88 257 .31 274 .72 19.95 21.45 24. 55 40.058 4 6.19 5 5.747
D 177.1 218.94 270 .57 22.67 22.92 27. 84 40.536 4 8.5 5 2.083
E 184.46 2 41.82 2 74.37 22. 83 21.58 26.75 3 9.58 41.81 4 9.814
F 1 49.48 1 93.98 2 76 .01 16.55 20.8 23 33.567 45. 47 47. 464
G 118.44 2 27.09 3 01.71 20. 01 23.38 23 35.439 46. 19 50. 889
H 177.92 245.2 280.67 17.45 20.39 29.68 41. 571 46. 27 46. 986
I 169.64 138 .54 243 .97 15.87 13.78 31. 15 35.598 3 7.63 3 9.102
J 165.93 236.98 268 .53 20.17 26.34 31. 07 42.288 4 3.8 4 6.986
Table 4. Unit weight of test body.
Gr o up Cont rol 1 Cont r ol 2 A B C D E F G H I J
(g/cm3) 2.17 2.19 1.75 1.79 1.85 1.81 1.86 1.86 1.87 1.85 1.78 1.81
4.3. Influence of General Mortar and Bottom Ash on Strength
According to Figure 1, group Control 1 and Control 2, using natural fine aggregate with water cement ratio is
0.7 and 0.68 respectively, have 7 days compressive strengths over 200 kg/cm2. Mean while, the strength of Con-
trol 2 and Group B, due to their lower water cement ratio, get correspondingly higher strength, compare to the
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Figure 1 . Relation diagram between sand and bottom ash.
W/C = 0.7 in control 1and group A. However, although Group A and B have the same water cement ratio like
group Control 1 and Control 2 respectively, due to using IBA fine aggregates only, regardless of the material
age, t he str engt hs are ar ound 30% l ower tha n tho se of t he contr ol gro up. T he strength developments still follo w
the general theory, i.e. lower water-binder ratio will generate higher strength. However, adding mineral admix-
tures, fly ash or furnace slag, to replace cement, the strength trends are not as regular.
4.4. Influence of Mineral Admixture Substituting Cement on Strength
Table 3 shows the st rengt h of mortar having t he same W/C r atio with dif ferent miner al admi xture s. The groups
having 0.7 W/C ratio all reach 250 kg/cm2 aver age s tr en gt h o f 56 d a ys, e xp ec t Gr o up A whi ch ha s no a d mi xt ure
(IB A fi ne a g gregat es o n l y), w hil e t he str e ng th of G ro up G wh ic h has 1 0 % f urna ce sla g r e ac hed o ver 3 0 0 kg/c m2.
The strengt h of gr oups with mi neral admixt ure is about 1 00 kg/ cm2 lo wer tha n that o f the contr ol gro up, the r e-
duced strength of Group A is twice lo wer tha n the group with mineral admixture. W hen the other mixture pro-
portion is fixed but only alter the water cement ratio, though the difference of W/C ratio is only 0.02, the strength
differences are rather obvious. The strength of group Control 2 at 28 days, Is almost the same as group Control 1
at 56 d a ys age . W he n t he a ge r ea che s 5 6 d ays, the s tr en gt h o f gro up Contr o l 2 is higher t ha n 40 0 kg /cm2, gr o up s
with mineral admixture at 56 days also reach over 250 kg/cm2; however the strengths of 0.68 W/C ratio is
slightly lo wer than those with 0.7 W/C ratio.
4.5. Direct Tensile Test Result
As sho wn i n Figure 2, compared with cement mortar of control groups, strength of IBA fine aggregate mortar is
30%-40% lower. The test results of other groups with mineral admixtures are the same as the results of com-
pressive stre ngth test. The tensile strength varied slightly of groups with 0.7 W /C ratio, Figure 3 shows tha t the
strengths of each group are close to each other and differ no more than 2%, regardless adding furnace slag or fly
ash. While the strengths of groups with 0.68 W/C ratio have greater difference, as shown in Figure 4, each
group differs about 3% - 5%.
4.6. Flexural Tensile Test Result
The differences between mortar in control groups and in IBA fine aggregate mortar are as shown in Figure 5,
which shows the same trend as results of direct tensile test. As shown in Figure 6 and Figure 7, the strength
developing trend of 0.68 and 0.7 water cement ratio are rather similar, despite 10% differences, the developing
trends are q uit flat. All the test results sho w that whe n aggre gate is substit uted b y IBA fine aggregate s, the lo wer
water cement ratio dose not develop higher strengt h. Altho ugh the Figure 6 and Figure 7 show similar trends,
however being compared to control groups, in Figure 7, 0.68 W/C ratio groups gain quite lo w strength, about 40%
lower than group Control 2, while in Figure 6, 0.7 W/ C rati o grou ps is a roun d 20% weake r th an group Control 1.
The study sho ws that, based on the 1:2 cement/aggregate weight ratio, Incinerator bottom ash (IBA) fine aggre -
gates mortar, unit weight around 1.8 g/cm3, is 20% lighter natural fi ne aggregate mortar, u nit weight around 2.2
M.-J. Yang et al.
Figure 2. Tensile strength relations among control groupsand bottom ash only groups.
Figure 3 . The tensile strength relationship among W/C 0.7 admixture replacement of cement.
Figure 4. The tensile strength relationship among W/C 0.68 admixture replacement of cement.
Figure 5. The flexu ral strength relationship between control group and bottom ash group.
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Figure 6. The flexural strength relationship among W/C 0.7 mineral admixture replacement of cement.
Figure 7. The flexural strength relationship among W/C 0.68 mineral admixture replacement of cement.
g/cm3. T he ratio of unit weight is corresponding to the ratio of specific gravity between IBA fine aggregate, Gs
2.2, and natural fine aggregate, Gs 2.68. The IBA fine aggregates mortar can only reach 60% - 70% the com-
pressive strength of natural fine aggregates mortar. In terms of compressive strength versus unit weight, the
lightweight effect of cement mortar or cement related product by using IBA fine aggregates is unable to com-
pensate the strength losses. In IBA fine aggregates mortar, the mineral admixtures fly ash and furnace slag do
not help in raisin g strengths of the morta r specimens, which is contradictory to the genera l concepts that fl y ash
and furnace slag will increase the compressive strength at later age of cement concrete. Tensi le st rengt hs o f IBA
fine aggregates mortar obtained from direct tensile strength and flexural tensile strength tests are 15% and 30%
of compressive strength respectively, there is no obvious difference to the strength percentages obtained from
natural fine aggregate mortar. The research suggests that the strength of IBA fine aggregates is the main factor
to determine the strengths of the IBA fine aggregates mortar or concrete, due to the irregular strength develop-
ment, which does not follow general concepts, such as low W/C ratio and mineral admixtures will not necessar-
ily help i n s t rength developme nt in IBA fine aggregate s mortar.
 Hwang, C. L. (2007) Pozol ana Concrete Using Manual. Sinotech Engineering Consultants, Inc., Taipei.
 Taiwan Construction Research Institute (2007) Fly Ash and Steel Furnace Slag Application Plan Evaluation Report,
China Hi-Ment Cor porat ion Entrust Plan, Plan No: TRC -93003.
 Wu, G.Y. (2012) Discussion on Bottom Ash Concrete Building Block Brick Wall. Master Thesi s , Civil Engineering
Department, NPU ST.
 Hsieh, Y.-T. (2008) Preliminary Study on Previous Concrete Subject to Freeze Thawing, Fire or Dust Falls. Master
Thesis, Construction Engineering Department, CYUT.
 Hong, Y.-L. (2009) Study on EAF Slag Concrete Applied on Permeable Surfacing. Master Thesis, Department of
Harbor and River Engineering, NTOU.