Construction and Building Materials: Turhan Bilir, Osman Gencel, Ilker Bekir Topcu
Construction and Building Materials: Turhan Bilir, Osman Gencel, Ilker Bekir Topcu
Construction and Building Materials: Turhan Bilir, Osman Gencel, Ilker Bekir Topcu
h i g h l i g h t s
a r t i c l e i n f o a b s t r a c t
Article history: Coal power plants produce million tons waste fly ash worldwide that cause environmental problem and
Received 21 February 2015 threaten people health. Moreover, its depoting costs are high and need extensively large depot areas.
Received in revised form 24 March 2015 Recycling is a strategy to consume waste content left from several industries. Although fly ash has been
Accepted 1 May 2015
used in cement and concrete technology. In concrete technology it has been used as supplementary
Available online 21 May 2015
cementitious material or replacement material with a portion of cement until now. But, it has not been
considered as fine aggregate. In this study, the effect of fly ash as fine aggregate in mortars is investigated.
Keywords:
Flow ability, unit weight, ultrasound pulse velocity, compressive and flexural strengths, modulus of elas-
Fly ash
Mortar
ticity, stress–strain behavior and free drying and restrained shrinkage tests were conducted on mortars
Fine aggregate produced. It was observed that the usage of fly ash as fine aggregate presents a new approach to consume
Recycling high amount of fly ash without causing significant changes on properties of mortars when it was used at
the ratio of 60–70%.
Ó 2015 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.conbuildmat.2015.05.095
0950-0618/Ó 2015 Elsevier Ltd. All rights reserved.
T. Bilir et al. / Construction and Building Materials 93 (2015) 782–789 783
Gencel et al. [2] used waste ferrochromium slag as replacement material with a portion of cement up to 30–40%. But, fly ash has
aggregate with natural limestone based aggregate in concrete. not been considered as an aggregate in mortar and concrete until
They reported that ferrochromium aggregates increase mechanical now. Aggregates occupy high volume about 75–80 wt.% of con-
properties and wear resistance of concrete. crete. Thus, aggregates significantly influence the performance of
Uygunoglu et al. [3] used demolished concrete wastes to pro- concrete [2]. In this respect, the usage of FA as aggregate in con-
duce interlocking paving block. And they observed that paving crete and mortar presents a new approach to consume high
blocks produced with these recylced aggregates had strength amount of FA.
desired, 3.6 MPa. López Gayarre et al. [4] have produced concrete In this study, the evaluation of fly ash as fine aggregate in mor-
kerbs and floor blocks with recycled aggregates replacing two tar is investigated. Thus, flow ability, unit weight, ultrasound pulse
types of natural aggregates. They have concluded that the proper- velocity, compressive and flexural strengths, modulus of elasticity,
ties and manufacturing properties are little bit lower than those of free and restrained drying shrinkage tests are conducted on mor-
the produced with only the natural aggregates. Another study of tars produced.
Lopez-Gavarre et al. [5] indicates the similar compressive strength
of recycled aggregate concrete similar to the ones of ordinary con- 2. Materials and method
crete and they have found that the effect of curing conditions affect
the compressive strength of recycled aggregate concretes likewise CEM II/B-M 32.5 cement was used as hydraulic binder complying with TS EN
197-1 [16]. Cement was obtained from Set cement factory in Eskisehir, Turkey.
ordinary concrete.
Chemical composition of cement is presented in Table 1. The specific gravity, speci-
Topcu and Bilir [6] used waste crushed tile as fine aggregate in fic surface area, flexural and compressive strengths were determined corresponding
mortar. They observed that there is no problem the usage of to TS EN 196-1 [17]. Specific gravity and specific surface of cement used were
crushed tile up to the ratio of 60% replacement in point of mechan- 2.85 g/cm3 and 3574 cm2/g. Compressive strengths of cement at 2, 7 and 28 days
were 12.8, 26.9 and 39.5 MPa, respectively.
ical strength since at this ratio compressive strength is above
Modified polycarboxylate based high-rate water-reducing superplasticizer (SP)
20 MPa. Also, the usage of crushed tile reduces drying shrinkage was used to avoid the possibility of increase in water demand of mortars and to pro-
and crack with due to it. vide a satisfactory workability. Its density at 20 °C is 1.08–1.1 g/cm3. Its pH and
Li and Zhao [7] evaluated granulated blast furnace slag in con- solid content are 5.7% and 40%. Standard sand (SS) (Rilem-Cembreu) with high silica
crete. And they observed that concrete with granulated blast fur- content was used as reference sand to produce mortar. The sizes of SS grains remain
below 2 mm.
nace slag has early and long term compressive strengths and
The FA fine aggregate was provided from Catalagzı Thermal Power Plant in
resistance to chemical attach and corrosion. Zonguldak, Turkey. FA fine aggregate was used to replace standard sand (SS).
Park et al. [8] used waste glass as aggregate in concrete since Physical and chemical properties of FA are given in Table 2. The FA was used accord-
recycling it as aggregate can be useful in point of conservation ing to ASTM C 618 [18]. The FA is classified as class C and class F according to ASTM
environment and economical advantage. They obtained compres- C 618. The sum of SiO2 + Al2O3 + Fe2O3 must be more than 50% for class C and 70%
for class F. FA was classified as F type according to the code because total of major
sive strength over 30 MPa when waste glass was used at 70% oxides in FA is 89.59%. The SS is coarser than the FA. About 82% of FA grains are
replacement ratio. below the size of 200 lm. 49% of FA grains are below 2 mm. Approximately 1% of
Eldin and Senouci [9] conducted experimental studies to inves- FA grains are finer than 0.08 mm and these finer particles may lead to increment
tigate usability of waste tires as aggregate in cement based con- in water demand. However, round shape of FA grains and usage of superplasticizer
have decreased it. In this study, FA has replaced with the standard sand by weight.
crete. They observed that although the usage of waste tires with
Mixture proportioning was based on the absolute volume method. Six mortars
different sizes and contents as aggregate in concrete decrease com- with 40 40 160 mm size from each mixture were prepared with Portland
pressive strength, concrete with waste tire aggregates did not cement as binder, standard sand, superplasticizer and fly ash as aggregate. The FA
show brittle failure, and had energy absorption capacity under was replaced with the SS at different concentrations (10–100 wt.% at 10% intervals).
loads. The mix proportions of series are given in Table 3. After keeping demolded mortar
specimens at 20 °C and 90% relative humidity for 24 h. specimens were immersed
Singh and Siddique [10] conducted a study on incorporation of into water with 23 ± 2 °C for 7 and 28 days. On fresh mortars, flow table test was
bottom ash as replacement fine aggregate up to 100% for natural done to determine the effect of the FA on workability according to ASTM C 1437
sand in concrete. Compressive strength of concrete containing [19]. Compressive and flexural strength tests were done according to ASTM C 349
100% bottom ash instead of natural sand has no strength loss when [20] and ASTM C 348 [21]. The modulus of elasticity was determined according
to ASTM C 469 [22]. Stress and strain values were calculated using force, shortening
compared with that of conventional concrete. But, bottom ash used
and dimensions of specimen. The r–e curves were plotted using the calculated val-
as fine aggregate increases water demand to obtain workability ues. Modulus of elasticity was calculated by the curves and the initial tangent
desired. The usage of water reducer admixture compensates it. method. Ultrasonic pulse velocity was determined according to ASTM C 597 [23].
Anwar et al. [11] produced concrete with rice husk ash at differ- Unit weight of hardened mortar was determined according to Archimedes principle.
ent ratios up to 40% of cement content and investigated character- Free drying shrinkage was determined by measuring the lengths changes according
to ASTM C 157 [24] on specimen with 25 25 285 mm.
istics of concrete produced. They observed that rice husk ash is a The restrained drying shrinkage crack formation is provided by attempting ring
very active pozzolanic material and its usage in concrete increases test. Three ring type mortar specimens were produced for measuring the restrained
mechanical strength even at early ages, durability such as chloride drying shrinkage crack widths. After 24 h, the outer steel ring molds of specimens
ions impermeability and decreasing permeability. were removed. Specimens were subjected to drying at 23 ± 2 °C and 50 ± 4% relative
humidity. Crack developments were observed and measured every day during
As understood a literature survey above, concrete technology
60 days. Crack widths were measured using an optical crack microscope every
has a capacity of consume wastes incorporating them useful prod- day. Ring specimens were exposed to drying conditions from only the outer circular
ucts, and also has environmental advantages pretty significant in surface of mortar. Top surface was sealed with silicone. So, internal stresses
point of sustainability of natural resources since no natural
resources have limitless reserves.
Another waste material is fly ash. Fly ash, a by-product of coal Table 1
Chemical composition of cement (wt.%).
power plants, causes environmental pollution and its storage cost
is pretty high. Turkey produces about 18 million tons waste fly SiO2 31.53
ash per year [12]. It is about 80 million tons per year in India Al2O3 7.06
Fe2O3 3.29
[13]. Overall fly ash content worldwide is about 600 million tons CaO 48.89
[14]. MgO 1.46
There are many papers published about the usage of fly ash in SO3 2.01
cement and concrete technology [15]. Fly ash is considered effec- Free Cl 0.27
Loss on ignition 4.55
tively as a supplementary cementitious material or replacement
784 T. Bilir et al. / Construction and Building Materials 93 (2015) 782–789
Table 2
Properties of fly ash used as fine aggregate.
occurred were not uniform due the non-uniform stress distribution by inner steel
ring additional to uniform stress distribution. Ring specimen is shown in Fig. 1. If
Fig. 1. Ring specimen for restrained drying test.
a cross section has been taken and looked from the side of the ring it is seen that
the ring mortar specimens have the height of 140 mm, the outer diameter of
320 mm and the inner diameter of 250 mm. In this manner, the thickness of the
ring mortar specimen is as 35 mm. Besides, the ring mold also includes an inner Table 4
steel ring at the inner diameter of 200 mm and the outer diameter of 250 mm Flow diameters of mortars with FA fine aggregate and standard sand.
(Inner surface of the mortar ring contact with the outer surface of this steel ring).
FA content (%) Flow diameter (mm) Relative changes (%)
Therefore, it has the thickness of 25 mm and restrains the drying shrinkage of ring
mortar specimen leading to the internal stresses and cracking. 0 194 100
10 191 98.5
20 189 97.4
3. Results and discussion 30 187 96.4
40 184 94.8
50 183 94.3
3.1. Flow table test
60 180 92.8
70 178 91.8
Flow diameters of fresh mortars are presented in Table 4. All 80 175 90.2
mortars were flexible and easy to handle, and were easily com- 90 172 88.7
pacted by hand compaction and easily finished. High water absorp- 100 168 86.6
Table 3
Mixture proportions.
Table 5
Relative variations of unit weight of mortars.
Table 7
Relative variations of flexural strength of mortars.
Fig. 6. Relation between ultrasound pulse velocity and unit weight of mortars.
Fig. 7. Flexural strengths with respect to FA content. Fig. 9. Compressive strengths with respect to FA content.
T. Bilir et al. / Construction and Building Materials 93 (2015) 782–789 787
Table 8
Relative variations of compressive strength of mortars.
Fig. 10. Experimental statically modulus of elasticity. Fig. 12. Free drying shrinkage of mortar specimens.
788 T. Bilir et al. / Construction and Building Materials 93 (2015) 782–789
3.8. Drying shrinkage cracks relation between compressive strength and flexural strength of
cement based materials. Flexural strength behavior of mortars
Variations of crack width are presented in Fig. 13. Crack with FA presents the same trend observed on compressive strength
occurred at top of outer surface of specimen into its bottom. of mortars with FA. Although FA decreases elasticity modulus, FA
Crack width increases with time advancing. As seen from Fig. 13, increases strain capacity of mortar. Free drying shrinkage increases
FA delays the crack formation. Crack width development changes with increment in FA. But, crack width shows a decreasing trend.
depending on FA content. Crack with development of reference And crack formation is delayed.
specimen stops at 27 days. For specimens containing FA, it is Future work is planned using fly ash as fine aggregate in con-
between 31 and 41 days depending on FA content in the mixture. ventional concrete and self-compacting concrete in order to
Crack widths can be related with free drying shrinkage and water increase the consumption of fly ash waste.
loss. Decreases in crack widths are observed for series containing
FA as fine aggregate up to 70%. Relative increment is in question
References
for the series containing higher contents than 70%. Series contain-
ing between 70% and 100% content of FA are very close to each [1] Gencel O, Koksal F, Erdogmus E, Martínez-Barrera G, Brostow W. Properties of
other. concrete paving blocks made with waste marble. J Clean Prod
Initial cracks measured at days of 14, 15, 20, 23, 24, 27, 29, 30, 2012;21(1):62–70.
[2] Gencel O, Koksal F, Ozel C, Brostow W. Combined effects of fly ash and waste
31 and 33 for 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and ferrochromium on properties of concrete. Constr Build Mater 2012;29:633–40.
100% FA, respectively. Although crack widths stops between 27 [3] Uygunoğlu T, Topcu IB, Gencel O, Brostow W. The effect of fly ash content and
and 41 days, crack developments at first week of specimen produc- types of aggregates on the properties of pre-fabricated concrete interlocking
blocks (PCIBs). Constr Build Mater 2012;30:180–7.
tion. Development after ultimate value is not significant due to [4] Lopez-Gayarre F, Lopez Colina C, Serrano-Lopez MA, Lopez Martinez A.
lower acceleration. Acceleration of increase in crack widths is Manufacture of concrete kerb and floor blocks with recycled aggregate from
lower for specimens containing higher FA. Use of FA in mortars construction and demolition waste. Constr Build Mater 2013;40:1193–9.
[5] Lopez-Gayarre F, Lopez Colina C, Serrano-Lopez MA, Domingo-Cabo A. The
reduces cracking due to drying shrinkage. Crack occurrence is effect of curing conditions on the compression strength of recycled aggregate
delayed. And crack widths develop slowly and become lower with concrete. Constr Build Mater 2014;53:260–6.
increment in FA ratio in mixture. [6] Topcu IB, Bilir T. Effect of bottom ash as fine aggregate on shrinkage cracking of
mortars. ACI Mater J 2010;107(1):48–56.
[7] Li G, Zhao X. Properties of concrete incorporating fly ash and ground
granulated blast-furnace slag. Cement Concr Compos 2003;25:293–9.
4. Conclusions [8] Park SBLB, Kim JH. Studies on mechanical properties of concrete containing
waste glass aggregate. Cem Concr Res 2004;34(12):2181–9.
[9] Eldin NaS A. Rubber-tire particles as concrete aggregate. J Mater Civ Eng
The key findings of the using FA as fine aggregate in mortar are 1993;5(4):478–96.
as follows: [10] Singh M, Siddique R. Strength properties and micro-structural properties of
concrete containing coal bottom ash as partial replacement of fine aggregate.
The usage of FA as fine aggregate in the mixture reduces work- Constr Build Mater 2014;50:246–56.
ability. When it is used at the ratio of 100%, workability loss is [11] Anwar M, Miyagawa T, Gaweesh M. Using rice husk ash as a cement
13.4%. Still it has enough workability. Unit weights of hardened replacement material in concrete. Waste Manage 2000;1:671–4.
[12] Yazıcı H. The effect of silica fume and high-volume Class C fly ash on
mortars are in the range of 2.32–1.47 kg/dm3 at 28 days. FA usage mechanical properties, chloride penetration and freeze–thaw resistance of
significantly reduces unit weight which is desirable in point of self-compacting concrete. Constr Build Mater 2008;22(4):456–62.
reducing cross sections of structural elements and dead load. [13] Siddique R. Effect of fine aggregate replacement with Class F fly ash on the
abrasion resistance of concrete. Cem Concr Res 2003;33(11):1877–81.
Reducing dead load is very important to lightening the earthquake
[14] Ahmaruzzaman M. A review on the utilization of fly ash. Prog Energy Combust
damage and saving life. Weight loss is 36.6% when FA is used at the Sci 2010;36(3):327–63.
ratio of 100%. Ultrasound pulse velocity decreases depending on FA [15] Rashad AM. An exploratory study on high-volume fly ash concrete
content up to 21.3% which is corresponding to 0.91 km/s when FA incorporating silica fume subjected to thermal loads. J Clean Prod
2015;87(15):735–44.
is used at 100%. Compressive strength is the most important char- [16] TS EN 197-1, Turkish standard for cement-part 1: compositions and
acteristic. FA reduces compressive strength up to 73.1%. conformity criteria for common cements. Ankara, Turkey; 2002.
Compressive strengths of mortars with FA range of 39.55– [17] TS EN 196-1, Turkish standard for methods of testing cement-part 1:
determination of strength. Ankara, Turkey; 2002.
12.1 MPa at 28 days. For structural application, 20 MPa is required. [18] ASTM C 618, Standard specification for coal fly ash and raw or calcined natural
In this respect, 70% replacement ratio is allowed. 70% replacement pozzolan for use in concrete. Annual Book of ASTM Standards, Pennsylvania,
ratio is a high ratio to consume this waste when mortar and con- USA; 2008.
[19] ASTM C 1437, Standard test method for flow of hydraulic cement mortar. West
crete production is considered annually worldwide. There is a close Conshohocken, USA; 2007.
[20] ASTM C 349, Standard test method for compressive strength of hydraulic-
cement mortars (using portions of prisms broken in flexure). West
Conshohocken, USA; 2002.
[21] ASTM C 348, Standard test method for flexural strength of hydraulic-cement
mortars. West Conshohocken, USA; 2002.
[22] ASTM C 469, Standard test method for static modulus of elasticity and
Poisson’s ratio of concrete in compression. West Conshohocken, USA; 2002.
[23] ASTM C 597, Standard test method for pulse velocity through concrete.
Pennsylvania, USA: Annual Book of ASTM Standards; 1997.
[24] ASTM C 157, Standard test method for length change of hardened hydraulic-
cement mortar and concrete. West Conshohocken, USA: ASTM International;
2014.
[25] Duran-Atis C. Strength properties of high-volume fly ash roller compacted and
workable concrete, and influence of curing condition. Cem Concr Res
2005;35(6):1112–21.
[26] Haque N, Al-Khaiat H. Strength and durability of lightweight concrete in hot
marine exposure conditions. Mater Struct 1999;32(7):533–8.
[27] Beycioglu A, Aruntas HY. Workability and mechanical properties of self-
compacting concretes containing LLFA, GBFS and MC. Constr Build Mater
2014;70:626–35.
[28] Formosa J, Chimenos J, Lacasta A, Haurie L, Rosell J. Novel fire-protecting
mortars formulated with magnesium by-products. Cem Concr Res
Fig. 13. Crack widths obtained from ring test. 2011;41(2):191–6.
T. Bilir et al. / Construction and Building Materials 93 (2015) 782–789 789
[29] Babu KG, Babu DS. Behaviour of lightweight expanded polystyrene concrete [32] Youm KS, Jeong YJ, Han ESH, Yun TS. Experimental investigation on annual
containing silica fume. Cem Concr Res 2003;33(5):755–62. changes in mechanical properties of structural concretes with various types of
[30] Nguyen L, Beaucour A-L, Ortola S, Noumowé A. Influence of the volume lightweight aggregates. Constr Build Mater 2014;73:442–51.
fraction and the nature of fine lightweight aggregates on the thermal and [33] ACI Committee 213, Guide for structural lightweight aggregate concrete.
mechanical properties of structural concrete. Constr Build Mater Detroit: American Concrete Institute, ACI 213R-03; 2003. 38p.
2014;51:121–32. [34] Hamid R, Yusof K, Zain M. A combined ultrasound method applied to high
[31] Rossignolo JA, Agnesini MV, Morais JA. Properties of high-performance LWAC performance concrete with silica fume. Constr Build Mater 2010;24(1):94–8.
for precast structures with Brazilian lightweight aggregates. Cement Concr [35] Kewalramani MA, Gupta R. Concrete compressive strength prediction using
Compos 2003;25(1):77–82. ultrasonic pulse velocity through artificial neural networks. Automat Constr
2006;15(3):374–9.
[36] Neville AM, Properties of concrete. 4th ed. Pearson Prentice Hall; 2008.