Construction and Building Materials 94 (2015) 315–322

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Construction and Building Materials

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Strength properties and molecular composition of epoxy-modifiedmortars

http://dx.doi.org/10.1016/j.conbuildmat.2015.06.0560950-0618/� 2015 Elsevier Ltd. All rights reserved.

⇑ Corresponding author.E-mail addresses: j.mirza@utm.my, mirza7861@gmail.com (J. Mirza).

Nur Farhayu Ariffin a, Mohd Warid Hussin b, Abdul Rahman Mohd Sam c,Muhammad Aamer Rafique Bhutta d, Nur Hafizah Abd. Khalid a, Jahangir Mirza b,⇑a Construction Material Research Group (CMRG), Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310 Johor, Malaysiab UTM Construction Research Centre (UTM CRC), Block C09, Level 1, Institute for Smart Infrastructure and Innovative Construction, Universiti Teknologi Malaysia,81310 Johor, Malaysiac Department of Structure and Materials, Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysiad Department of Civil Engineering, Faculty of Applied Sciences, University of British Columbia, Vancouver, B.C. V6T 1Z4, Canada

h i g h l i g h t s

� Addition of epoxy resin without hardener.� Epoxy resin enhanced the mechanical properties of mortar.� Epoxy-modified mortar increased strength with prolonged curing period.

a r t i c l e i n f o

Article history:Received 19 January 2015Received in revised form 1 June 2015Accepted 26 June 2015

Keywords:Epoxy resinStrengthStrength developmentEpoxy-modified mortar

a b s t r a c t

Even without hardener, epoxy resin is able to harden in the presence of hydroxyl ions produced duringcement hydration process. In this study commercially available Bisphenol A-type epoxy resin withouthardener was used as a polymeric admixture to prepare epoxy-modified mortars, whose propertiesand chemical composition were then investigated. The mortars were prepared with a mass ratio of 1:3(cement:fine aggregate), water-to-cement ratio (W/C) of 0.48, and epoxy content of 5%, 10%, 15% and20% of cement. The specimens were subjected to dry and wet–dry curing. Workability, setting time, com-pressive strength, flexural strength, and tensile splitting strength tests were conducted. A Fourier trans-formation infrared spectroscopy test was also administered to determine the molecular composition andstructure of mortars. Results showed an inverse relationship between workability and setting time ofmortars versus epoxy content. The compressive, flexural, and tensile splitting strengths ofepoxy-modified mortars were noted to be the highest for mortars containing 10% epoxy in wet–dry cur-ing. A significant improvement in strength development of mortars without hardener had been achievedthrough dry curing due to gradual hardening of epoxy resin with hydrated cement.

� 2015 Elsevier Ltd. All rights reserved.

1. Introduction

High adhesion and chemical resistant properties of epoxy resinshave led to their extensive usage as adhesives andcorrosion-resistant paints in the construction industry. They arealso used as an admixture in concrete to impart certain effectson mortars. However, the preparation of conventionalpolymer-modified mortars using epoxy resins cannot be realizedwithout the use of hardener [1]. A previous study by Kakiuch [2]showed that epoxy resins can harden in the presence of alkalis

whereby the authors succeeded in developing polymer-modifiedmortars using epoxy resin without any hardener. The aforemen-tioned application was countered by Ohama [3] who posited thatepoxy resin without hardener, in concrete and mortar at ambienttemperature has lower rate of hardening and strength. In orderto overcome that problem, an autoclave curing and steam curingprocess was used to bring about early strength development ofepoxy-modified mortar and concrete. In contrast, the studyreported in this paper found that applying ambient curing temper-atures to the epoxy-modified mortar resulted in achieving therequired strength of mortar. The recent study about the epoxyresin without hardener was reported by Jo [4]. The author statedthat, the properties of epoxy cement mortars without hardener

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Cement hydrate

Fig. 1. FESEM morphology of cement hydrates without epoxy resin.

Fig. 2. Digital Brookfield Viscometer for epoxy resin viscosity test.

Table 2Properties of epoxy resin.

Epoxyequivalent

Molecularweight

Density (g/cm3,20 �C)

Viscosity (Pa s,20 �C)

Flash point(�C)

184 380 1.16 10,000 264

Table 3Mix proportion of epoxy-modified mortar.

Sand(kg/m3)

Cement(kg/m3)

Water(kg/m3)

Epoxycontent (%)

Water/cement

Sand:cement

1517 506 228 0 0.48 3:1

316 N.F. Ariffin et al. / Construction and Building Materials 94 (2015) 315–322

improved fairly when compared to epoxy mortar with hardener.This is due to the cross-linking of an epoxy resin in the environ-ment of Portland cement that have accessibility to react with cal-cium hydroxide without the presence of hardener [5].

Beside mechanical properties, the molecular structure ofepoxy-modified mortar is also important as it shows the reactioninside the concrete when epoxy resin was added. How epoxy resinwould perform without added hardener can be analyzed throughan experiment. For in-situ monitoring processes such as curing,phase separation or even ageing, the interpretation of the spectraand assignment of the bands are critical. Fourier transformationinfrared spectroscopy (FTIR) has been widely used for the charac-terization of organic compounds for which reliable informationand spectra can easily be located.

In the reported research, polymer-modified mortars using epoxyresin without hardener were prepared with various epoxy-cementcontents; they were then tested for compressive strength and flexu-ral strength. Normal ordinary cement mortars were also preparedand tested in the same manner as control specimens.

2. Experimental

2.1. Materials

2.1.1. CementThe cement used in the study was ordinary Portland cement (OPC) obtained

from Holcim Cement Manufacturing Company of Malaysia, conforming to ASTMC150 [6] standard. The chemical properties of the cement obtained from X-RayFluorescence (XRF) analysis test are given in Table 1. From the analysis, it showsthat the highest constituent in Portland cement is calcium oxide which is 62% fol-lowed by silica oxide with 20%. Alumina and iron oxide give the percentage of com-position of 6% and 3%, respectively. Fig. 1 shows the morphology of Field EmissionScanning Electron Microscopy (FESEM) picture of cement hydrate. Cement is gener-ally comprised of various calcium silicates (alite, belite, etc.), tri-calciumaluminateand tetra-calcium aluminoferrite.

2.1.2. Fine aggregateLocal river sand with specific gravity of 2.62 and fineness modulus of 2.85 in

saturated surface dry condition was used. The fine aggregate was oven-dried andthen wetted until saturated surface-dry condition was reached.

2.1.3. Epoxy resinDiglycidyl Ether of Bisphenol A-type epoxy resin was used in the proportion

mixture as shown in Fig. 2. The epoxy resin was stored at room temperature toavoid damage. The amount of epoxy resin added in the mix was in the range of5–20% of total cement content. The properties of pure epoxy resin are given inTable 2. The Diglycidyl Ether of Bisphenol A-type was chosen as the viscosity ofepoxy resin must be high in order for it to react with cement phase. As mentionedearlier in the text, the epoxy resin used did not contain any hardener. The viscositytest of epoxy resin was conducted using Digital Brookfield Viscometer (20-2millioncP) in accordance to ASTM D2983-09 [7]. The result showed the viscosity of epoxywas 10,000 Pa s.

2.2. Experimental procedure

2.2.1. Preparation of epoxy-modified mortarThe design mix of epoxy-modified mortar basically followed that of ordinary

cement mortar and concrete. With reference to JIS A 1171 [8] the hardener-freeepoxy-modified mortars were mixed with a mass ratio of 1:3 cement to fine

Table 1Chemical composition of ordinary Portland cement.

Constituent Percentage by weight (%)

Silica, SiO2 19.8Alumina, Al2O3 5.6Iron oxide, Fe2O3 3.4Calcium, CaO 62.7Magnesia, MgO 1.2Sodium, Na2O 0.02Phosphorus, P2O5 0.1Loss of ignition, LOI 2.1Lime saturated factor 1.0

5101520

aggregate; epoxy content of 5%, 10%, 15% and 20% of cement; and a water–cementratio of 0.48. The flow diameters of the mortars were in the range of 170 ± 5 mm.Mortar cube specimens of 70 � 70 � 70 mm were cast for compressive strength testand prism specimens of 40 � 40 � 160 mm were cast for flexural test. For tensilesplitting test cylindrical specimen sized 150 mm in height and 70 mm in diameterwas used.

All specimens were subjected to dry and wet–dry curing for 28 days. Normalmortar was prepared as a control specimen. Table 3 shows the mix proportion ofepoxy-modified mortar.

N.F. Ariffin et al. / Construction and Building Materials 94 (2015) 315–322 317

2.2.2. Mixing procedureIn order to prepare the mortar mixtures, a mechanical mixer (20 L capacity)

with a rotating speed of 80 rpm was used. The fine aggregates were initiallyblended and mixed for 1 min for all mixtures. The amount of water added was cal-culated to bring the sand to saturated-surface-dry condition. Then cement wasintroduced and mixed well for about 5 min until homogenous condition wasachieved. The epoxy resin without hardener was slowly poured into the mixtureand mixed for another 5 min. Finally, the calculated amount of water was intro-duced into the mixer and blended for another 10 min. The test specimens were thenwell compacted using a vibrating table for 10 s.

2.2.3. CuringWet–dry curing and dry curing were applied for all epoxy-modified mortar

specimens without hardener. For wet–dry curing the specimens were placed underwet burlap for two days and followed by five days in water. Afterwards, the speci-mens were taken out and placed in room temperature for 21 days. For dry curingregimen the specimens were cured under wet burlap for two days and then leftat room temperature for another 26 days. The normal mortar went through watercuring process.

2.2.4. Fresh properties of mortar mixtureFresh properties of mortar were evaluated in order to determine the perfor-

mance of the mixture. There are several tests that can be performed for fresh mortarmixture; however this study considered only flow and setting time tests. The flowtest for workability measurement was conducted in accordance to ASTM C230 [9]by using flow table while setting time test was accomplished according to ASTMC191 [10].

2.2.5. Water absorption and apparent porosityThe water absorption test was needed to investigate the performance of

epoxy-modified mortar after being soaked in water for 24 h. The percentage ofabsorption was calculated in accordance with ASTM D6532 [11] and ASTMC1403-13 [12]. The average three 70 � 70 � 70 mm mortar cubes were cast andplaced in water for 24 h to determine water absorption. Once saturated, the speci-mens were oven-dried. The weight of each specimen was recorded and calculated.

To determine the apparent porosity of mortars, three cubes were oven-dried at85 �C for 24 h and then immersed in water for 48 h. The same specimens were thensuspended in water and their weight measured.

2.2.6. Compressive strengthThe compressive strength test for epoxy-modified mortar was executed using a

compression test machine in Civil Engineering Material and Structure laboratoryaccording to BS EN 12390 [13]. An increasing compressive load was applied tothe specimen until failure occurred in order to obtain the maximum compressiveload. The cube size was 70 � 70 � 70 mm in accordance with BS EN 998-1:2010[14] and the calculated compressive strength was based on the average value.

2.2.7. Flexural and tensile splitting testsThe prism specimen was tested for flexural strength after 28 days in accordance

to ASTM C348-08 [15]. The size of mortar prism was 40 � 40 � 160 mm. The spec-imens were tested for various percentages of epoxy resin content. The ability of thespecimen to resist deflection under load was evaluated and studied by doing theflexural test.

161.0

163.0

165.0

167.0

169.0

171.0

173.0

0 5 1

Dia

met

er, m

m

Epoxy C

Fig. 3. Relationship between flow

The tensile splitting test was carried out for cylindrical specimen (150 mm inheight and 70 mm in diameter) that was cast and tested at an interval of 28 days.The test conformed to ASTM C496 [16].

2.2.8. Field Emission Scanning Electron Microscopy (FESEM)FESEM was performed by coating the samples with gold prior to analysis, and

Energy-dispersive X-ray (EDX) rendered at an accelerating voltage of 15 KV. Thespecimens analysed by FESEM analysis were taken from the fractured pieces ofthe samples.

2.2.9. Fourier transform infraredFourier transform infrared (FTIR) analysis was performed using the KBr pellet

method (1 mg sample per 100 mg KBr) on a spectrometer with 32 scans per samplecollected from 4000 to 400 cm�1 at 4 cm�1 resolution.

3. Results and discussion

3.1. Workability test

The workability of epoxy modified mortar was measured byusing a flow table test to check the consistency of fresh mortarsbefore casting. Fig. 3 depicts the flow diameter measured andrecorded. It is apparent in the graph that normal mortar gave170 mm flow diameter whereas it was 172 mm for 5% of epoxymodified mortar. The flow decreased as the epoxy content wasincreased to 10%, 15%, and 20% resulting in a diameter of 170,169 and 166 mm respectively. Furthermore, it became clear thatan increase in epoxy content decreased the workability of mortardue to the high viscosity of Bisphenol A-type epoxy resin. Thediameter of fresh mortar flow was recorded in the range of170 ± 5 mm.

3.2. Setting time

Fig. 4 shows setting time test results. The graph indicates thatpercentage of epoxy content is inversely proportional to the settingtime. The use of high viscosity epoxy resin made the mixture moreviscous and it hardened quickly. The normal mortar setting timewas 20% greater than that of epoxy-modified mortars.

3.3. Water absorption and apparent porosity

The performance and absorption of epoxy-modified mortarunder wet environment exposure were scrutinized through waterabsorption test. Fig. 5 elaborates the outcome. An inversely propor-tional relationship was noticed between water absorption and

0 15 20ontent, %

diameter and epoxy content.

0

50

100

150

200

250

300

350

0 5 10 15 20 25

Setti

ng T

ime

(min

utes

)

Epoxy Content (%)

Fig. 4. Relationship between setting time and epoxy content.

318 N.F. Ariffin et al. / Construction and Building Materials 94 (2015) 315–322

epoxy content. The specimens under dry curing absorbed morewater than specimens under wet–dry curing. It was probablybecause the wet–dry curing specimens had completed the hydra-tion and polymerization process, hence produced a denser mortar.Evidently, dry curing specimens tend to absorb more water inorder for the hydroxyl ion (OH�) to react with unhardened epoxyresin in epoxy-modified mortar.

The apparent porosity of various percentages of epoxy resin isshown in Fig. 6. The porosity percent of normal mortar was higher

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0 5% 10%

Wat

er A

bsor

ptio

n (%

)

Epoxy Co

Fig. 5. Relationship between water

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

0 5% 10%

App

aren

t Por

osity

(%)

Epoxy C

Fig. 6. Relationship between appare

compared to epoxy-modified mortars. After 48 h in water theapparent porosity of normal mortar was 12% compared toepoxy-modified mortar containing 10% resin, whose porosity wasrecorded as 6%. The relevance of apparent porosity is manifestedin the strength and durability of the specimens. When the apparentporosity is diminished, the specimen is obviously dense and wellcompacted leaving minimum void within the specimens.

3.4. Effect of curing process

A comparative analysis of dry curing and wet–dry curing meth-ods was undertaken to evaluate the effects of both on the proper-ties of epoxy-modified mortar. Fig. 7 presents the compressivestrength of epoxy-modified mortar which had been subjected toboth curing conditions for a period of 28 days. The wet–dry curingprocess revealed a higher compressive strength. Perhaps such phe-nomenon could probably be explained in terms of cement’s naturalcharacteristic requiring water in the early stage to initiate thehydration process. Under dry curing, the specimens were notexposed to water at all resulting in incomplete hydration processeffecting only limited hydroxyl ions production. On the contrary,wet–dry curing provided the optimum condition for both hydra-tion and polymerization processes. Consequently the amount ofhydroxyl ions was sufficient to react with epoxy resin and bolstermortar strength.

The favorable curing condition for epoxy-modified mortar dif-fers from that of ordinary cement mortar because its sealant

15% 20%ntent (%)

Dry curedWet dry cured

absorption and epoxy content.

15% 20%ontent

Dry cured

Wet dry cured

nt porosity and epoxy content.

20151053

38

36

34

32

30

28

26

24

22

20

Epoxy Content, %

Com

pres

sive

Stre

ngth

, MPa

Dry curedWet dry cured

Type of Curing vs Epoxy Percentage

Fig. 7. Relationship between curing condition and percentage of epoxy.

N.F. Ariffin et al. / Construction and Building Materials 94 (2015) 315–322 319

consists of two phases of epoxy and cement with different proper-ties. Optimum strength in the cement phase is developed underwet conditions (water immersion and high humidity), whereasstrength development in the epoxy resin is attained under dryconditions.

0

5

10

15

20

25

30

35

40

0 5 10 15 20

Com

pres

sive

Stre

ngth

(MPa

)

Epoxy Content (%)

Fig. 8. Relationship between compressive strength with various epoxy content forwet–dry curing.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 5 10

Flex

ural

Stre

ngth

(MPa

)

Epoxy Con

Dry curedWet dry cured

Fig. 9. Relationship between flexur

Wagner’s research [17] showed that polymer modification ofcement mortar and concrete is governed by both cement hydrationand polymer film formation processes in their binder phase. Thecement hydration process generally precedes the polymer forma-tion process.

3.5. Compressive strength

The percentage of epoxy resin was varied from 5% to 20%. After28 days of wet–dry curing, the specimens were tested for theircompressive strength. Fig. 8 exhibits differing amounts of epoxyresin in mortar, which were added to the mortar to study its effecton compressive strength. The compressive strength of normal mor-tar without epoxy resin was 30 MPa at 28 days while the compres-sive strength of 10% epoxy resin was 36 MPa, which was thehighest among all epoxy content variations, as well as higher thanthat of normal mortar strength. This could be due to the presenceof OH� ions from the hydration of Ca(OH)2.

The sample containing 5% epoxy resin manifested 33 MPa com-pressive strength. Moreover, when epoxy content was increasedbeyond 10% the compressive strength declined. Perhaps theunhardened epoxy resin could be to blame, which had been previ-ously reported by Ohama [18]. According to Ohama, the reductionsin the flexural and compressive strengths of polymer-modifiedmortars which used epoxy resin without hardener atpolymer-cement ratios of 20% or more, may be the result of consid-erable amount of unhardened epoxy resin left in polymer-modifiedmortars. Excessive amount of epoxy resin inside the mortar prob-ably disrupted the hydration and polymerization process.

3.6. Flexural test

Investigation of the material’s ability to resist deformationunder load was done through the flexural test. The result of theepoxy-modified mortar is shown in Fig. 9. It can be seen that mor-tar with 10% epoxy content revealed the highest flexural strengthfor both curing regimens followed by the 5%, 15%, and lastly 20%ones. Evidently the 10% epoxy-modified mortar exhibited highestflexural strength leading to the conclusion that epoxy resin reactedwell with the hydroxyl ions from cement hydrate. Hence the mor-tar produced became denser, stronger with greater durability.

15 20tent (%)

al strength and epoxy content.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0 5 10 15 20

Tens

ile S

treng

th (M

Pa)

Epoxy Content (%)

Dry cured Wet dry cured

Fig. 10. Relationship between tensile splitting strength and epoxy content.

180120905628

39

38

37

36

35

34

33

32

31

30

Age, Days

Com

pres

sive

Stre

ngth

, MPa

10% WDC10% DCNormal mortar

Fig. 11. Relationship between compressive strength and age of specimens.

320 N.F. Ariffin et al. / Construction and Building Materials 94 (2015) 315–322

3.7. Tensile splitting test

Tensile splitting strength test results of all specimens are shownin Fig. 10. The graph shows that normal mortar had lower tensilestrength than epoxy modified mortars. The 10% epoxy resinshowed the highest tensile strength among all specimens exposedto wet–dry curing condition. Beyond 10% epoxy additions in factlowered the tensile strength. Again, it may well be attributed tothe improvement in cement hydrate and polymer.

3.8. Strength development

With results as shown in Figs. 7 and 8, the 10% epoxy contentspecimen was selected to undergo a strength development test.

Hardened Epoxy Resin

Fig. 12. FESEM morphology of 1

This test was carried out by prolonging curing time in dry condi-tion. Fig. 11 shows the development in compressive strength after180 days of curing. The graph delineates that the 10%epoxy-modified mortar continued to gain strength even after180 days. Normal mortar showed an increase in compressivestrength until 120 days and stabilized thereafter. During dry curingof the 10% epoxy mortar, the strength development was relativelysimilar to that of 10% epoxy-modified mortar under wet–dry cur-ing, albeit at lower rate. The results of the test were fairly conclu-sive in favor of epoxy resin without hardener for use as anadmixture in mortar.

Besides compressive strength, the microstructure of specimenswas also tested. Fig. 12 displays the Field Emission ScanningElectron Microscopy (FESEM) morphology of mortar comprisingof 10% epoxy content. It characterizes the bonding between hydro-xyl ion and epoxy resin. The bonding is primarily important to pro-duce a strong mortar and serves as proof that epoxy resin hasreacted well with hydroxyl ions even in the absence of hardener.

3.9. Fourier transformation infrared spectroscopy (FTIR)

Fig. 13 represents the Fourier transformation infrared spec-troscopy (FTIR) for both epoxy-modified mortar and normal mor-tar. FTIR is a technique which is used to obtain an infraredspectrum of absorption, emission, photoconductivity or Ramanscattering of solid, liquid or gas. The goal of any absorption spec-troscopy is to measure how well a sample absorbs light at eachwavelength which later will determine the material’s molecularcomposition and structure.

Bonding between

hydroxyl ion and

epoxy resin

0% epoxy-modified mortar.

Stretching O-H of

Ca(OH)2

C=C ring stretch

Deformation

CO3Si-O

Wavenumber, cm-1

Epoxy-modified mortar

Epoxy ring stretch

Out-of-plane

bending of phenyl

ring

OPCmortar

Abs

orba

nce

Fig. 13. Fourier transformation infrared spectroscopy (FTIR) for epoxy-modified mortar and normal mortar.

Table 4Comparison of composition and structure of normal and epoxy-modified mortars.

Wavelength Composition

Normal mortar Epoxy-modified mortar

3000–4000 Stretching O–H ofCa(OH)2

Stretching O–H of Ca(OH)2

1200–1700 Deformation H–O–H C@C ring stretch800–1200 CO3 Epoxy ring stretch300–700 Si–O Out-of-plane bending of phenyl

ring

N.F. Ariffin et al. / Construction and Building Materials 94 (2015) 315–322 321

The FTIR tests for epoxy-modified mortar only took into consid-eration the specimen with 10% of epoxy as all others showed thesame composition. The FTIR measurements were performed toobtain more details about the components of epoxy-modified mor-tar (Fig. 13). The normal mortar was tested for the sake of compar-ison. All those samples have a complex group of bands in the rangeof 300–700 cm�1, corresponding to stretching vibration of Si–Obonds for normal mortar. In the case of epoxy modified mortarbending of phenyl ring was noticed. Moreover, the bands in therange of 1200–1700 cm�1 corresponded to asymmetric stretchingof CO3 for normal mortar. It was caused by the penetration ofCO2 when the sample was exposed to air. In case of epoxy resinadded to mortar, the composition was different since the epoxyring was stretched at the same wavelength. The deformation ofbands between 1200 and 1700 cm�1 was seemingly due to H–O–H bending vibration of molecular H2O [19] while C–C ring of phe-nol group was stretched in epoxy-modified mortar. The broad bandin the range of 3000–4000 cm�1 corresponds to stretching vibra-tions of O–H groups in H2O or hydroxyls with a wide range ofhydrogen-bond strengths for both mortars. The summary of com-position and structure is shown in Fig. 13 and Table 4.

4. Conclusion

The test results lead to the following conclusions:

1. The amount of epoxy content that produced the highest com-pressive strength, flexural strength, and strength developmentwas 10%. The compressive strength and flexural strength wererecorded as 36 and 3 MPa, respectively after 28 days.

2. The most suitable curing regimen for epoxy-modified mortarwas wet–dry curing; it provided a good circumstance for hydra-tion process of cement and polymerization of epoxy to occur.

3. Strength development observed in the 10% epoxy-modifiedmortar showed an increasing trend after 180 days of curing

compared to normal mortar whose strength started to stabilizeafter 120 days.

4. Fourier transform infrared spectroscopy test demonstrated thatepoxy resin could react with hydroxyl ions and strengthen thecomposition of mortar far more than normal mortar.

Acknowledgements

The authors greatly appreciate Ministry of Education (MOE),Universiti Teknologi Malaysia (UTM) and Research ManagementCentre (RMC) UTM for financial aid that helped carry outQJ1300000.2509.06H56 research project. The authors are alsoindebted to the technical staff of Materials and Structures labora-tory for the support and facilities provided for experimental work.

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Strength properties and molecular composition of epoxy-modified mortars1 Introduction2 Experimental2.1 Materials2.1.1 Cement2.1.2 Fine aggregate2.1.3 Epoxy resin

2.2 Experimental procedure2.2.1 Preparation of epoxy-modified mortar2.2.2 Mixing procedure2.2.3 Curing2.2.4 Fresh properties of mortar mixture2.2.5 Water absorption and apparent porosity2.2.6 Compressive strength2.2.7 Flexural and tensile splitting tests2.2.8 Field Emission Scanning Electron Microscopy (FESEM)2.2.9 Fourier transform infrared

3 Results and discussion3.1 Workability test3.2 Setting time3.3 Water absorption and apparent porosity3.4 Effect of curing process3.5 Compressive strength3.6 Flexural test3.7 Tensile splitting test3.8 Strength development3.9 Fourier transformation infrared spectroscopy (FTIR)

4 ConclusionAcknowledgementsReferences