studies on mortars containing waste bottle glass and industrial by-products

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Construction and Building Materials 22 (2008) 1288–1298

and Building

MATERIALS

Studies on mortars containing waste bottle glassand industrial by-products

Omer Ozkan a, _Isa Yuksel b,*

a Alaplı Vocational School, Zonguldak Karaelmas University, 67850 Alaplı, Zonguldak, Turkeyb Department of Civil Engineering, Zonguldak Karaelmas University, 67100 Zonguldak, Turkey

Received 27 February 2006; received in revised form 28 November 2006; accepted 30 January 2007Available online 23 March 2007

Abstract

This study presents investigation of properties of cement-based mortars produced with cement containing waste glass (WG) andindustrial by-products. The features, compressive strength, sulfate and chloride resistance, high temperature resistance, and expansionsrelated to alkali–silica reaction (ASR) are examined. Three series of mortar specimens containing ground WG are prepared. Only groundWG is replaced cement in the first series. Ground WG, ground granulated blast-furnace slag (GGBFS) or fly ash (FA) is replaced cementin the second and third series. The results showed that compressive strength was decreased as replacement level increased. The observedlosses in early strength of mortars were relatively higher than strength losses measured at 28th day. Minor increases in strength wereobtained at 10% and tolerable decreases in strength were observed at 30% replacement levels. The same trend is also valid for durabilityproperties examined in this study. Hence it is concluded that combined usage of WG and GGBFS, or WG and FA will be more suitableinstead of using WG alone in mortar.� 2007 Elsevier Ltd. All rights reserved.

Keywords: Waste glass; By-product; Durability; Replacement; Strength

1. Introduction

Environmental pollution and increases in manufactur-ing and storage costs in our era towards human being torecycle wastes. Besides, it is being an obligation for the sakeof sustainability. In this context, construction industry,especially cement and concrete sector, has started todevelop new usage forms or recycling procedures of indus-trial wastes. In this way, they give to some help to reduceenvironmental pollution. Various ashes, waste glass(WG), and slag are examples of these materials that studiedabout recycling it. For example, many usage forms weredeveloped for fly ash (FA) as result of these studies. Atthe end, FA is an industrial resource instead of being a

0950-0618/$ - see front matter � 2007 Elsevier Ltd. All rights reserved.

doi:10.1016/j.conbuildmat.2007.01.015

* Corresponding author. Tel.: +90 372 2574010x1541; fax: +90 3722574023.

E-mail addresses: [email protected], [email protected] (_I.Yuksel).

solid waste. Glass is being used in daily life in many fieldssuch as bottle glass, flat glass, bulb glass. In many of these,the time of usage is very short and even the WG is collectedand stored, they continue to be a problem for the environ-ment unless they are recycled and used [1].

The aim of this paper is to investigate mechanical anddurability properties of mortars incorporating groundWG (clear, green, and brown), FA and granulated blast-furnace slag (GBFS) partially substituted with cement.Resistance to sulfates (Na2SO4, MgSO4), resistance to hightemperature, and resistance to chloride ions were assessedby conducting tests on 7 and 28 day age mortar specimens.Furthermore, expansions caused by alkali–silica reaction(ASR) were attempted to measure for these replacements.The results of experimental study were evaluated and someconclusions were reported about strength and durability ofmortars produced with replacement of ground GBFS, WG,and FA.

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O. Ozkan, _I. Yuksel / Construction and Building Materials 22 (2008) 1288–1298 1289

2. Literature review

The features of concrete containing WG as cementingmaterial or aggregate were investigated by many research-ers. Shao et al. [2] used finely ground WG as partial cementand they showed that ground glass having a particle sizefiner than 38 micron did exhibit pozzolanic behavior. Also,pozzolanic activity was studied by Caijun et al. [3]. Theyshowed that finely ground glass powders exhibited veryhigh pozzolanic activity. The finer the glass powder is,the higher its pozzolanic reactivity is. A strong improve-ment of the mortar mechanical performance was detectedby Corinaldesi et al. [4], due to the positive contributionof the WG to the micro-structural properties. On the otherhand, some researchers were tried to use WG in concrete asan aggregate. According to Topcu and Canbaz [5], WG asaggregate did not have a marked effect on the workabilityof concrete. While WG replacement decreased the slump,air content and fresh unit weight, it increased flowing andVeBe values. Park et al. [6] were investigated mechanicalproperties of concretes containing WG aggregates. Theystated that compressive, tensile, and flexural strengths ofconcretes containing the WG aggregates demonstrated adecreasing tendency along with an increase in the mixingratio of the WG aggregates. The concrete containing WGaggregates of 30% mixing ratio gave the highest strengthproperties.

In addition, studies about the possibilities of usingWG as asphalt additives and road filler are being made.The practices that are stated above stayed on a limitedlevel, because of the ASR that is formed because of thereactive silica on the WG and the high level of alkalienvironment on concrete ingredients and also the harmfulexpansions that are results of this environment. The ASRresults in the production of two component gels. Onecomponent is a non-swelling calcium–alkali–silicate–hydrate and the other is a swelling alkali–silicate–hydrate[N(K)–S–H] [7]. The alkali–silicate–hydrate gel which candestroy the bond between the aggregate and the hardenedcement paste and which absorbs water and swells to asufficient extent to cause cracking and disruption of theconcrete [8]. In recent times, some investigations are con-ducted to prevent the ASR expansions in the concreteand to recycle the waste glass [1,2]. With the aim of pre-venting the expansion in the concrete, puzzolanic, organicand inorganic additives with by-products are widely used[9].

In recent past, many research-development studies weremade on the topic about using FA in production of con-crete and glass-ceramic [10–13]. Furthermore, FA is moreappropriate for production of cement and glass-ceramicwith respect to slag [14]. Currently, only a small percentageof FA is utilized, mainly in the cement industry.

GBFS is a potential hydraulic binder. The traditionalusage of GBFS is having a partial replacement materialin Portland cement. Usually, replacement of slag inPortland cement decreases the early strength, however,

increases the late strength and improves the durability ofthe concrete [15].

3. Experimental procedures

3.1. Materials

CEM-I type Portland cement (PC) was used in experi-ments that cement is convenient with the Turkish StandardTS EN 197-1 which was translated from EN 197-1. It has42.5 MPa compressive strength value for 28 days. GBFSis provided from Eregli Iron and Steel Factory and wasgrinded in a laboratory mill. FA was provided from Zon-guldak Catalagzı Thermal Power Plant. Clear (CG), green(GG) and brown (BG) bottle glasses are grinded in labora-tory for 5 h. Before grinding, bottles were crushed by ahammer to granulate it. GBFS was also grinded in labora-tory for 4 h. A jar mill was used for grinding samples to thedesired particle size. Thirty kilograms balls and 10 kgsamples were placed in the mill in each time. The chemicaland physical features of PC, GBFS, FA and glasses areshown in Tables 1 and 2, respectively. CEN standard sandthat was defined in TS EN 196-1 was used in production ofmortar specimens.

3.2. Sample preparation and test methods

Mortar specimens were produced in three series accord-ing to the procedure described in TS EN 196-1. Each seriescontains three color groups (clear (C), green (G), andbrown (B)) for each replacement ratio (Table 3). Portlandcement was replaced only WG in the first series. Series 2contains GBFS with WG. The third series contains a com-bination of FA and WG. Also reference specimens weremanufactured for comparison of results. The mortarspecimens were manufactured in two types in shape forall series. The first type specimen was prisms having40 · 40 · 160 mm dimensions prepared for compressiontest. The second type specimens were mortar bars forASR test which specimens have 25 · 25 · 285 mm indimensions. The ratio of cement/sand/water was selectedas 1/3/0.5 as given in TS EN 196-1. In all series, three dif-ferent color glasses are substituted in ratios of 10%, 30%and 50% of cement by weight. The details of mixture pro-portions are shown in Table 3.

The compressive strength test specimens that are origi-nally 40 · 40 · 160 mm in dimensions were placed in aroom where the temperature was 20 ± 3 �C for 24 h. Thenthey were demolded and placed in a water tank where thetemperature was 20 ± 3 �C for the next 6 days. Three ofthe specimens were tested at 7th day and the other threespecimens were tested at 28th day. A computer-controlledcompression machine was used and the loading speed ischosen to be 1 kN/s. The following sample preparationmethod was applied for compression test. The compressivestrength test specimens were prisms originally 40 · 40 ·160 mm in dimensions at first. At the test date, they were

Table 1Chemical composition of materials

PC (%) GBFS (%) FA (%) CG (%) GG (%) BG (%)

SiO2 20.52 35.12 56.15 73.04 71.30 72.10Al2O3 5.11 17.54 25.00 1.81 2.18 1.74Fe2O3 2.84 0.72 7.34 0.04 0.60 0.31CaO 63.62 37.83 4.72 11.50 11.26 11.57MgO 1.59 5.51 1.54 0.32 0.54 0.46SO3 3.00 0.75 0.42 0.22 0.05 0.13L.O.I. 1.96 1.08 1.62 – – –

Table 2Physical properties of materials

PC GBFS FA CG GG BG

Specific gravity 3.16 2.09 2.07 2.62 2.59 2.60Specific surface (cm2/g) 3300 3720 2815 4830 4780 4672Fineness (wt.%) >32 lm 21 18 32 12 12 14Fineness (wt.%) >90 lm 0.8 0.6 2.4 0.6 0.7 0.8Fineness (wt.%) >200 lm 0.1 0.1 1.1 0.1 0.1 0.1Vicat setting time (h:min) 190/225 – – – – –Volume expansion (mm) 1 – – – – –

Table 3Mixture details

Series Designation of groupsa Mix detail PC WG FA GBFS

Reference 100% PC 100 – – –1 C10 G10 B10 90% PC + 10% WG 90 10 – –

C30 G30 B30 70% PC + 30% WG 70 30 – –C50 G50 B50 50% PC + 50% WG 50 50 – –

2 CS10 GS10 BS10 90% PC + 5% WG + 5% GBFS 90 5 – 5CS30 GS30 BS30 70% PC + 5% WG + 15% GBFS 70 15 – 15CS50 GS50 BS50 50% PC + 25% WG + 25% GBFS 50 25 – 25

3 CF10 GF10 BF10 90% PC + 5% WG + 5% FA 90 5 5 –CF30 GF30 BF30 70% PC + 15% WG + 15% FA 70 15 15 –CF50 GF50 BF50 50% PC + 25% WG + 25% FA 50 25 25 –

PC: Portland cement; WG: waste glass; FA: fly ash; GBFS: granulated blast-furnace slag; C: clear glass; G: green glass; B: brown glass; CS: clear glass andGBFS; GS: green glass and GBFS; BS: brown glass and GBFS; CF: clear glass and FA; GF: green glass and FA; BF: brown glass and FA.

a Group code names arranged so that each code shows color code for WG.

1290 O. Ozkan, _I. Yuksel / Construction and Building Materials 22 (2008) 1288–1298

cut into three equal cubic parts carefully by using a cuttingmachine. Then the compressive strength test was conductedwith these cubic parts whose dimensions are nearly equal to40 · 40 · 40 mm. Dimensions of each part are checked witha vernier calliper and surface area was determined beforethe test. The average compression strength value of thesenine cubic parts was noted as the result of test group.

Resistance to sodium chloride and sulfates were testedby comparing compressive strength of specimens exposedto these chemicals with the strength of reference specimens.Mortar specimens were cured in a curing room for 20 �Cfor 24 h after casting. They were immersed in pure watertill the end of 7th day that the temperature of water is20 ± 3 �C. After that, each specimen was cut into threecubic parts (each of them 40 · 40 · 40 mm in dimensions)as described for compression test. Then, cubic parts ofspecimens were divided into three groups. Each groupwas put in 4% Na2SO4, 4% MgSO4, and 4% NaCl solutions

respectively at 20 ± 3 �C for next 21 days. Finally, the com-pressive strength of these cubic parts was measured.

ASR test was conducted in accordance with ASTM C1260. Test specimens (25 · 25 · 285 mm mortar bars) weremade of cement, sand and water with the following ratio(1:2.25:0.47). After 24 h of curing, the bars were placed inwater at 80 �C for another 24 h to gain a reference length.Then, they were transferred to a solution of 1 N of NaOHat 80 �C. Readings were then taken every day for 14 days.At the end of 14 days, the length differences of specimenswere compared to reference specimens.

To observe the high temperature resistance, the mortarspecimen groups are exposed to three different high tem-peratures (300, 700 and 1000 �C). Dimensions of any testspecimen were 40 · 40 · 40 mm. Prismatic (40 · 40 ·160 mm) specimens were cut into three parts before the testlike for the compression test. Each test group was consti-tuted three cubic specimens. Every specimen groups were


put into a muffle furnace in room temperature (20 �C).Then the temperature of furnace was raised to target tem-perature. The rate of heating in the furnace was 6 �C/min.When the inner temperature of the furnace was reached tothe target temperature, specimens were removed from thefurnace. After the specimens were cooled down in air, com-pressive strength test was conducted.

4. Results and discussion

4.1. Compressive strength

Compressive strengths at 7th and 28th days were mea-sured for early and normal term strengths. These resultsare shown in Table 4. Compressive strength was generallydecreased as the replacement value increased. Howeverthere are some exceptional results such as the resultsobtained for 10% replacement level. The maximum com-pressive strength values are measured at 10% replacementlevel for both of 7th and 28th days. The maximum valueattained in 7-day groups was 36.84 MPa which is 10.7%higher than reference value. The maximum value attainedin 28-day groups was 47.56 MPa which is only 3.8% higherthan the reference value of 28-day groups.

Generally, pozzolans gives extra strength to mortarwhen used as finely ground. However pozzolans needs totime to show their extra strength since they use calciumhydroxide that is hydration product of Portland cement.Since GBFS will use calcium hydroxide, hydration of Port-land cement should begin at first. Then GBFS reacts withthe calcium hydroxide. This is the main reason of late set-ting and late strength gain. FA also shows similar behaviorin the mixture. Therefore the best results were observed inthe second series and the third series was followed it.

Relative compressive strength values are given in Fig. 1for 7 and 28 days old specimens. The relative compressivestrength is evaluated from the following equation:

f irel ¼ 100� ðfcj � frefÞ

fref

ð1Þ

Table 4Compressive strength change for 7 and 28 days

Series Repl. ratio (%) Compressive strength at 7th day

C G

Reference 0 33.28 33.281 (only WG) 10 32.55 35.09

30 26.93 28.2950 16.58 20.19

2 (GBFS + WG) 10 31.13 35.8230 30.96 29.0250 20.96 23.92

3 (FA + WG) 10 33.41 33.0530 26.36 28.0750 17.74 18.57

C: clear glass; G: green glass; B: brown glass.

fc represent the real compressive strength of jth group; fref

represent reference value of compressive strength; f reli rep-

resent relative compressive strength of group which is i-dayold. The relative strength of reference group is 100 accord-ing to Eq. (1).

Strength development with respect to replacement ratiofor 7 and 28 days old specimen groups are similar to eachother. 50–70% of 28th day’s strength is developed at 7thday in specimen groups of 7 days old. When replacementratio is 50% the strength measured at 7th day is changingbetween 51% and 62% of 28th days old. As replacementratio was increased compressive strength was decreased inall series. However the observed strength losses are chan-ged according to series. The maximum strength lossesobserved in 7 days old specimen groups were 50.20%,39.33%, and 42.26% for clear, green, and brown glasses.These maximum values are observed as 34.4%, 29.2%,and 27.7% for 28-day-old specimen groups. This resultshows that early strength losses are relatively higher thanstrength measured at standard time (28 days). On the otherhand, strength losses were decreased by using WG + GBFScombination instead of WG alone. Also WG + FA combi-nation is showed positive effect. However the best perfor-mance is resulted in WG + GBFS combination in ourstudy.

4.2. Durability properties

Not only strength development but also some durabilityproperties of mortars were investigated. Resistance to chlo-ride ions and sulfates, high temperature response, and ASRexpansions were discussed.

4.3. Resistance to NaCl

Residual compressive strength of specimens exposed toNaCl attack was shown in Fig. 2. Harmful effect of chlo-ride ions can be seen on Fig. 2. It was observed that asthe replacement ratio is increased the residual strength oftest groups is decreased. However the strength losses are

(MPa) Compressive strength at 28th day (MPa)

B C G B

33.28 45.83 45.83 45.8336.84 47.11 46.23 45.0029.95 38.74 40.95 40.6119.22 30.15 32.44 33.13

31.49 47.56 46.90 45.3328.15 39.75 44.48 42.3319.41 35.68 38.36 35.96

32.86 40.34 43.28 42.7625.64 38.90 38.60 41.3517.69 30.08 33.50 34.53

Series 1. 7 day

97.8

80.9

49.8

105.4

85.0

60.7

110.7

90.0

57.7

0

20

40

60

80

100

120

10 30 50

Replacement Ratio (%)

Rel

ativ

e C

om

pre

ssiv

e S

tren

gth

ClearGreenBrown

Series 2. 7 day

93.5 93.0

63.0

107.6

87.2

71.9

94.6

84.6

58.3

0

20

40

60

80

100

120

10 30 50

Replacement Ratio (%)

Rel

ativ

e C

om

pre

ssiv

e S

tren

gth

ClearGreenBrown

Series 3. 7 day100.4

79.2

53.3

99.3

84.3

55.8

98.7

77.0

53.2

0

20

40

60

80

100

120

10 30 50

Replacem ent Ratio (%)

Rel

ativ

e C

om

pre

ssiv

e S

tren

gth

ClearGreenBrown


84.5

65.8

100.9

89.4

70.8

98.2

88.6

72.3

0

20

40

60

80

100

120

10 30 50


Rel

ativ

e C

om

pre

ssiv

e S

tren

gth

ClearGreenBrown


86.7

77.9

102.397.0

83.7

98.9

92.4

78.5

0

20

40

60

80

100

120

10 30 50


Rel

ativ

e C

om

pre

ssiv

e S

tren

gth

ClearGreenBrown

Series 3. 28 day

88.084.9

65.6

94.4

84.2

73.1

93.390.2

75.3

0

20

40

60

80

100

120

10 30 50


Rel

ativ

e C

om

pre

ssiv

e S

tren

gth

ClearGreenBrown

Fig. 1. Relative compressive strengths for 7th and 28th days.


in minimum level in series 2, especially in S2-30 group forall colors of glasses. This result is caused by GBFS. There isa slight increase in residual strength for green and brownglasses in S2-30. Also, residual strengths of test groupsare higher than strength of control group for 10% replace-ment ratio in all series.

The results of this study are similar to results given in lit-erature. According to Park et al. [16] fineness of the WGand type of by-product are the greatest factors on the com-pressive strength. Similarly, Shao et al. [2] stated that ifglass that is grinded smaller than 38 lm it has an importanteffect on the compressive strength.

4.4. Resistance to MgSO4

Residual strengths of specimens cured in MgSO4 solu-tion was shown in Fig. 3. There is a decrease trend in resid-ual strength as replacement ratio is increased. Only oneexception was recorded in S1-10 group for brown glasswith 1.74% increase in residual strength. The highestdecrease was measured on S3-50 group. The residualstrength on this group is only 43.17% of reference group.However the losses in strength are relatively less in 10%and 30% replacement levels. For instance the maximumloss in strength was realized as 8.11% of reference speci-

41.2

0

31.4

2

25.8

8

41.1

3

34.9

3

33.1

8

39.7

3

33.4

3

25.7

8

44.8

8

37.5

0

31.9

8

40.0

0

39.8

6

34.2

6

44.7

2

37.2

6

29.2

8

43.6

0

37.6

9

31.2

8

41.3

8

41.9

6

32.7

0

44.8

2

37.6

5

29.7

7

38.5

9

0

10

20

30

40

50

Ref S1-10 S1-30 S1-50 S2-10 S2-30 S2-50 S3-10 S3-30 S3-50

Series and replacement percent

Com

pres

sive

str

engt

h af

ter

NaC

l atta

ck (

MP

a)

clear green brown

Fig. 2. Resistance of specimens to NaCl.

44.2

4

39.4

8

27.6

6

43.1

7

39.1

1

31.8

1

42.7

1

38.4

9

26.4

2

46.4

8

45.6

7

38.6

0

30.8

7

45.2

8

44.4

4

34.8

3

44.2

4

38.7

7

30.1

9

47.2

9

38.2

5

34.6

9

45.3

8

43.2

1

33.2

7

45.3

2

39.9

5

31.3

8

0

10

20

30

40

50

Ref. S1-10 S1-30 S1-50 S2-10 S2-30 S2-50 S3-10 S3-30 S3-50

Series and replacement pergentage

Clear Green Brown

Com

p. s

tren

gth

afte

r M

gSO

4 at

tack

(M

Pa)

Fig. 3. Resistance to MgSO4 of glasses.


mens for 10% replacement level. A comparison betweenstrength changes of specimens exposed to magnesium sul-fate attack and specimens cured in water is shown in Table5. According to Table 5, the maximum decrease in com-pressive strength was observed in S3-50 group with thevalue of 12.19%. On the other hand, slight decreases instrength were measured for 30% replacement level in allseries. Series 2 (WG + GBFS), series 3 (WG + FA), andseries 1 (WG) was the arrangement in order. Therefore itcan be concluded that series 2 at 30% replacement levelwas showed the best performance. Also, the color of glasseshas not an important effect on the residual strengths.

Additional C–S–H gel is formed when the pozzolansreact with Ca(OH)2. This formation increases resistanceto sodium sulfate attack but not to magnesium sulfateattack. Torii and Kawamura [18] have reported that, C–S–H produced by the pozzolanic reaction is more suscepti-

ble to the magnesium sulfate attack [17]. For the case ofmagnesium sulfate, brucite and C–S–H gel undergo toM–S–H gel which have not binding property. Thereforethe main damaging effect of magnesium sulfate solutionis decomposition of C–S–H gel to noncementitious M–S–H gel [19,20].

4.5. Resistance to Na2SO4

Fig. 4 shows residual compressive strength values of testgroups when they were exposed to sodium sulfate attack.Residual strengths obtained from S1 and S3 series for10% and 30% replacement levels are higher than thestrength that of reference group. Although for 50% replace-ment was made, residual compressive strength in S2 seriesis still higher than that of reference. These results show thatreplacement of cement by WG alone was increased durabil-

Table 5Alteration of residual compressive strength changes after MgSO4 attack

Clear glass Green glass Brown glass Loss in strength (%)

Water MgSO4 Water MgSO4 Water MgSO4 Clear Green Brown

Reference 45.83 46.48 45.83 46.48 45.83 46.48 1.40 1.40 1.41S1–10 47.11 44.24 46.23 45.67 45.00 47.29 �6.09 �1.21 5.09S1–30 38.74 39.48 40.95 38.60 40.61 38.25 1.89 �5.74 �5.81S1–50 30.15 27.66 32.44 30.87 33.13 34.69 �8.26 �4.85 4.71S2–10 47.56 43.17 46.90 45.28 45.33 45.38 �9.23 �3.45 0.12S2–30 39.75 39.11 44.48 44.44 42.33 43.21 �1.61 �0.07 2.07S2–50 35.68 31.81 38.36 34.83 35.96 33.27 �10.86 �9.19 �7.49S3–10 40.34 42.71 43.28 44.24 42.76 45.32 5.87 2.22 5.98S3–30 38.90 38.49 38.60 38.77 41.35 39.95 �1.05 0.43 �3.39S3–50 30.08 26.42 33.50 30.19 34.53 31.38 �12.19 �9.88 �9.11

35.6

7

35.1

3

32.0

6

41.7

1

39.7

8

33.2

8

41.6

6

35.8

0

27.0

0

33.7

8

43.3

8

37.0

3

32.2

1

40.5

7

43.6

2

33.7

8

43.7

5

35.1

2

28.8

5

44.2

6

39.0

1

31.0

2

44.0

8

41.3

0

33.8

2

43.8

8

39.0

2

30.7

0

0

10

20

30

40

50

Ref. S1-10 S1-30 S1-50 S2-10 S2-30 S2-50 S3-10 S3-30 S3-50

Series and replacement pergentage

Clear Green Brown

Com

pres

sive

str

engt

h af

ter

Na

2S

O4 a

ttack

Fig. 4. Resistance to Na2SO4 of glasses.


ity of mortars to sulfate attack. If WG is used as combiningwith GBFS or FA then sulfate resistance is more increased.Especially WG + GBFS combination gives the best results.It was not observed that, color of the glass has a significanteffect on sodium sulfate resistance. Although a decrease inthose strength values occurred after a 30% replacementratio, higher values than those of reference were obtained.

Brucite, ettringite, and gypsum are formed in the case ofmagnesium sulfate attack on cement-based materials [18].Ettringite formation results in cracking and expansion ofthe material. The expansion is related to the water absorp-tion of crystalline ettringite [19,20]. The presence of a poz-zolanic material results in an increase in the resistance tosodium sulfate attack. On the other hand, effectiveness ofpozzolanic material against sulfate attack is dependent onthe maximum temperature reached during the producingof the pozzolan. Wild et al. [21] concluded that the opti-mum calcining temperature for ground calcined brick clayin order to produce a pozzolan which imparts high sulfateresistance in mortar, is in the region of 1000–1100 �C.Ground calcined brick clay calcined at temperatures below900 �C produces a marked loss in sulfate resistance when

used to partially replace cement in mortar. Pozzolan mate-rials prevent harmful effect by binding Ca(OH)2 [22]. Someresults supporting this point of view were obtained in ourstudy and it was observed that WG, GBFS and FAincreased durability of mortar exposed Na2SO4 solution.

4.6. Alkali–silica reaction (ASR)

ASR test results were shown in Fig. 5. Expansion of mor-tar bars were observed more than 0.2% at the 14th day. Itwas stated in the appendix of ASTM C1260 that expansionsof more than 0.2% are indicative of potentially deleteriousexpansion. This limit value was also drawn in Fig. 5. ASRexpansion values are maximum for S1-50 group (includingclear glass with 50% replacement ratio). Only this grouphas higher expansion values for three type color glass thanreference group. S2 and S3 series have WG + GBFS andWG + FA combinations. The positive effects of these mate-rials (GBFS and FA) on expansion values can be seen fromFig. 5. All groups in S2 and S3 series have smaller expansionvalues than reference expansion value. There are gradualdecreases in expansion values as replacement ratio was

0.000

0.050

0.100

0.150

0.200

0.250

0.300

Ref. S1-10 S1-30 S1-350 S2-10 S2-30 S2-50 S3-10 S3-30 S3-50


Expa

nsio

n (%

)

Clear glass

Brown glass

Green glass

0.2% limit value

Fig. 5. ASR expansions of mortar specimens measured at the age of 14 days.


increased in these series. Also there are very small differencesin expansion values due to color of WG.

The minimum expansion value (0.204%) is observed forbrown glass in S3-50 group. This group mortars containsFA + WG combination. For the same color glass this valueis equal to 0.219% in S2-50 group and it is equal to 0.252%in S1-50 group. These results show that FA and GBFSwere decreased ASR expansions. Therefore combinationWG with FA or GBFS is more effective than the usageof WG alone. WG without any combination with FA orGBFS can substitute with cement up to 30%. Howeverthe replacement ratio can be increased up to 50% if WGwas combined with GBFS or FA. It can be seen fromFig. 5 that FA is more positive effect than GBFS.

Shao et al. [2] showed that as fineness of ground glassthat is replaced Portland cement is increases expansionsdue to ASR is decreases for 30% replacement. In addition,Shayan and Xu [1] stated that, when the replacement ratioof ground glass increased, ASR expansion values alsoincreased. In our study, while ASR expansion values werehigher than 0.2% limit value, a smaller value was obtainedcompared with the reference in general. Topcu [23] foundthat, clear glass yielded higher expansion value in respectto brown and green glasses. However, it was observed inthis study that colors of glasses have no significant effecton ASR expansions.

4.7. Resistance to high temperature

The residual compressive strengths of mortar groupsafter high temperature exposure were shown in Fig. 6 forclear glass. A residual strength index was defined in orderto facilitate comparison of results. Residual strength index(Rs) was defined as the ratio of residual compressivestrength of group tested at T �C high temperature (fT) tothe compressive strength of the same group tested at20 �C room temperature (f20).

Residual strength index of reference group was 16.59%for 1000 �C temperature. However, this index value wasevaluated as 38.04% in S3-30 group. Also, the other groupshave similar high residual strength indexes. While residualstrength index of reference group was evaluated as 46.72%for 700 �C temperature, higher index values were evaluatedin all the other groups for this temperature level. Theseresults showed that resistance to 1000 �C was improvedby WG or WG + by-product replacement. Residualstrength indexes for 50% replacement groups (S1-50, S2-50, S3-50) were greater than 100% for the temperature levelof 300 �C. However residual strength index was determinedabout 75% when the replacement ratio is low such as 10%.All of the results given above for clear glass showed thatwhen the replacement ratio was increased residual strengthindex was also increased.

Residual compressive strengths of groups containinggreen glass replacement were shown in Fig. 7. The behaviorof mortars in this section was similar to the case given inFig. 6. There are significant increases in residual strengthindex of groups when compared to reference group for1000 �C temperature level. Residual strength indexes were48.96% and 51% for S2-50 and S3-50 groups, respectively.WG + FA and WG + GBFS combinations are very effec-tive on high temperature response of mortar. If WG wasused alone as replacement material (series 1) residualstrength index was 26.59% that is higher than residualstrength index of reference group which was 16.59%. Thisresult shows that WG has positive effect on high tempera-ture resistance of mortar. Residual strength indexes evalu-ated for green glass is also similar to the case for clear glassfor 700 �C temperature. For instance, residual strengthindexes were evaluated as 46.72%, 53.4%, 50.52%, and67.46% for reference, S1-50, S2-50, and S3-50 groups,respectively.

Fig. 8 shows residual strength of groups with respect toseries and replacement ratio for brown glass. Residual

45.8 47

.1

38.7

30.2

47.6

39.8

35.7

40.3

38.9

30.1

34.2 35

.6

34.5

31.7

36.0

34.7 36

.6

34.3 37

.9

31.3

21.4 23

.3

20.2

16.1

22.6

23.4

18.3 19

.6 21.3

16.4

7.6 10

.2

9.5

10.0

11.2

10.6

10.7

11.7 14

.8

11.3

0

10

20

30

40

50

Ref. S1-10 S1-30 S1-50 S2-10 S2-30 S2-50 S3-10 S3-30 S3-50


Co

mp

ress

ive

stre

ng

th (

MP

a)

20 oC

300 oC

700 oC

1000 oC

CLEAR GLASS

Fig. 6. Effect of elevated temperature on clear glasses.

45.8

46.2

41.0

32.4

46.9

44.5

38.4

43.3

38.6

33.5

34.1 36

.5

40.5

33.4

39.0 42

.3

40. 1

36.8

37.8

35.1

21.4 23

.1

21.3

17. 3 19

.3 20.6

19. 4

18.3

17.5

22.6

7.6

7.7

10.9

7.9

11.6 13

.9

18.8

13.8 15.1 17

.1

0

10

20

30

40

50

Ref. S1-10 S1-30 S1-50 S2-10 S2-30 S2-50 S3-10 S3-30 S3-50Series and replacement percent

Co

mp

ress

ive

stre

ng

th (

MP

a)

20 oC

300 oC

700 oC

1000 oC

GREEN GLASS

Fig. 7. Effect of elevated temperature on green glasses.


strength index alteration for brown glass is similar to thecase for green or clear glass. Residual strength indexesfor 1000 �C temperature level were evaluated as 31.12%31.11%, and 32.17% for S1-50, S2-50, and S3-50 groups,respectively.

Generally, the following changes are observed in thestructure of concrete in different temperatures. The water,which is absorbed physically, leaves at 100 �C. Therefore,up to 300 �C, the best performance was given by pozzolanicconcretes and concretes made with siliceous aggregates.The water (in the form of steam) is eliminated most inten-sively and affects the surrounding phases of paste. Mainlydue to flow resistance and high temperature, steam createsa high pressure in the paste. For the pozzolanic material anadditional tobermorite gel was formed as a result of thepozzolanic reaction of Ca(OH)2 in ordinary Portlandcement, with reactive silica in pozzolanic material [24].

Similarly, in our study, while replacement ratio increases,an increase in residual compressive strength occurred too.Especially, higher residual strength index values wereobtained in the case of mortars, which GBFS-glass andFA-glass replacements at a ratio of 50%, than those ofthe mortars, which were not exposed to high temperatures.

It was known that decompositions begin to occur in thestructure of Ca(OH)2 at temperatures higher than 400 �C.Yuzer et al. [25] has stated that this decomposition has com-pleted at 530 �C. Moreover, C–S–H gels lose their cementability and dehydration occurs in the structure at tempera-tures higher than 600 �C. Mortar losses its all strength attemperatures higher than 800 �C [26,27]. Mortars in ourstudy lost about 50% of their compressive strength at700 �C and 70–75% of that at 1000 �C with respect to theirstrength before the high temperature exposure. Whenreplacement ratio gets higher, it has been observed an

45.8

45.0

40.6

33.1

45.3

42.3

36.0

42.8

41.4

34.5

34.2

38.3

37.5

33.7 37

.3 40.1

37.9

36.0 39

.5

36.6

21.4

21.6

17.9

17. 8

23.2

17.2 19

.3 20.7

18.9

19.2

7.6 9.

8 10.4

10. 3

11.4

11.9

11.2

9.9

10.4

11.1

0

10

20

30

40

50

Ref. S1-10 S1-30 S1-50 S2-10 S2-30 S2-50 S3-10 S3-30 S3-50


Co

mp

ress

ive

stre

ng

th (

MP

a)

20 oC

300 oC

700 oC

1000 oC

BROWN GLASS

Fig. 8. Effect of elevated temperature on brown glasses.


increase in high temperature durability. The color of glasshas not a significant importance with respect to high tem-perature resistance. FA showed better behavior than GBFSfor the high temperature resistance in this study.

5. Conclusions

The following conclusions can be drawn in this study.

� Compressive strength was generally decreased when thereplacement ratio was increased. Early strength lossesare relatively higher than strength losses measured at28th day.� WG + GBFS and WG + FA combinations showed bet-

ter results as compared with the case of WG was usedalone as replacement material. Series 2 (WG + GBFScombination) has the best performance among the threeseries.� Residual strength of test groups exposed to sodium

chloride attack was decreased as the replacement ratiowas increased. However the strength losses are in mini-mum level in series 2, especially in S2-30 group for allcolors of glasses. This result is caused by GBFS.� There is a decrease trend in residual strength as replace-

ment ratio was increased. Series 2 at 30% replacementlevel was showed the best performance for the MgSO4

attack. Replacement of cement by WG or combiningWG with by-products was increased durability of mor-tars to sulfate attack.� WG, GBFS and FA increased durability of mortar

exposed Na2SO4 solution. Especially WG + GBFS com-bination gives the best results for sulfate resistance.Color of the glass has not a significant effect on bothsodium sulfate and magnesium sulfate resistance.� FA and GBFS were decreased ASR expansions. There

are gradual decreases in ASR expansion values asreplacement ratio was increased. Also ASR expansions

are insensitive to color of WG. WG without any combi-nation with FA or GBFS can substitute with cement upto 30%. However the replacement ratio can be increasedup to 50% if WG was combined with GBFS or FA.� The samples, which were subjected to different tempera-

tures, yielded positive results in all temperatures and inall series. Especially, at 300 �C and the replacement ratioof 50%, compressive strength was higher than that of thesamples, which were kept in room temperature.� High temperature resistances of cement-based mortars

containing WG, WG + FA, and WG + GBFS wereimproved. Residual strength index was about two timeshigher than the residual strength index of reference mor-tar group.� Combined usage of waste glass with industrial by-prod-

ucts will be more suitable instead of using it alone forreplacement of cement.

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studies on mortars containing waste bottle glass and industrial by-products

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