Influences of EVA and methylcellulose on mechanical properties of Portland cement-calcium aluminate cement-gypsum ternary repair mortar

Construction and Building Materials 241 (2020) 118035

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Influences of EVA and methylcellulose on mechanical properties of Portland cement-calcium aluminate cement-gypsum ternary repair mortar Chen Shi, Xiwen Zou ⇑, Ping Wang College of Materials Science and Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, Shaanxi, China

h i g h l i g h t s
EVA improves flexural strength and toughness of ternary repair mortar.
Methylcellulose ensures the development of late strength.
EVA and methylcellulose improve flexural strength and avoid late strength loss.
The mechanisms include the changes of porosity and structure of hydration products.

a r t i c l e

i n f o

Article history: Received 12 June 2019 Received in revised form 2 December 2019 Accepted 1 January 2020

Keywords: Repair material Ethylene-vinyl acetate copolymer Methylcellulose Ettringite Modify

a b s t r a c t Portland cement–calcium aluminate cement–gypsum ternary repair mortar has the problems of poor toughness, low flexural strength and later strength retrogression in the process of road repair. The effects of ethylene-vinyl acetate (EVA) copolymer and methylcellulose on the mechanical properties of Portland cement–calcium aluminate cement–gypsum ternary repair mortar were investigated. The flexural strength of mortar increases with increasing content of EVA powder by less than 1.5% and the modified mortar with 1.5% EVA has better toughness but the late strength did not grow or was even lower than early strength. The combination of EVA and methylcellulose can effectively improve the flexural and compressive strengths and ensure the development of late strength. The acetic group of EVA copolymer consumes calcium hydroxide to produce calcium acetate under the basic condition, thus forming fine ettringite (AFt) crystal, which can improve the flexural strength with the filling effect of EVA particles. The methylcellulose has good water retention ability, which improves the stability of AFt and thus ensures the late strength. The combined addition of EVA and methylcellulose into the ternary system can improve the stability of AFt, optimize the crystal morphology of AFt, and increase the compressive strength and flexural strength, so as to ensure the development of strength in the later stage. Ó 2020 Elsevier Ltd. All rights reserved.

1. Introduction Damages in concrete structures and pavements are frequent due to the extended service periods of buildings and increased highway traffic. These infrastructures need to be maintained and repaired constantly. Repair mortar is widely used in modern construction. Portland cement mortar is a common repair material for construction and has good compatibility with existing concrete, but its shrinkage and lower flexural strength may lead to repair failure.

As a material for repair construction, it needs rapid hardening, shrinkage compensation, good adhesion, and excellent mechanical properties [1]. The ternary repair material of Portland cement–calcium aluminate cement–gypsum, which can meet these repair requirements well, are used extensively in the field of concrete construction repair [2–4]. This repair mortar can generate a large number of ettringite (C3A3CSH32, AFt) in the hydration process, which is based on the following reactions: Hydration reaction of CA phase in aluminate cement:

CA + 12H ! C3 AH6 + 2AH3

ð1Þ

The reaction between CA phase and gypsum: ⇑ Corresponding author. E-mail address: [email protected] (X. Zou). https://doi.org/10.1016/j.conbuildmat.2020.118035 0950-0618/Ó 2020 Elsevier Ltd. All rights reserved.





CA þ 3C S HX þ ð38  3xÞH ! C3 A3 C S H32 þ 2AH3

ð2Þ

2

C. Shi et al. / Construction and Building Materials 241 (2020) 118035

Hydration reaction of Portland cement:

C3 S þ H ! C  S  H þ CH

ð3Þ

C2 S + H ! C-S-H + CH

ð4Þ

tion mechanisms and the morphology of hydration products were studied by XRD and SEM. 2. Experimental program 2.1. Materials





C3 A þ 3C S HX þ ð32  3xÞH ! C3 A3 C S H32

ð5Þ

The composite system will have high early strength which due to the AFt rapid crystallization. The basic structural unit of AFt is {Ca3[Al(OH)6]12H2O}3+ shaped as a hexagonal rod. AFt contains 31–32 water molecules, so it will cause the cement to expand to 125% [5]. Thus, the shrinkage of Portland cement can be compensated, and the shrinkage cracking can be prevented. However, the composite system also have some disadvantages, for example low bond strength, low flexural strength, poor deformation adaptability, and the reduction of late strength, are still present [6,7]. Therefore, some materials must be used to modify this ternary repair material. Polymers are widely used to modify cement mortar and concrete to improve their mechanical property. For example, EVA [8], methylcellulose [9], styrene-butadiene rubber [10], as so on. Since ethylene vinyl acetate copolymer and methylcellulose has been widely used in modified mortar and concrete at present [11,12], it is necessary to investigate its effects on ternary repair materials. EVA is a common polymer modifier that improves the mechanical properties of cement mortar, such as EVA improves the flexibility, deformability [13], flexural strength [14], and bond strength of cement concrete [15]. Methylcellulose is added into the mortar for water retention property improvement and bonding property enhancement [16,17]. According to the research results of polymer modified Portland cement, EVA has a gradual filling effect on pores in the process of cement hydration, the acetic group of EVA copolymer consumes calcium hydroxide under basic condition to produce calcium acetate to improve the formation of AFt crystal of the cement mortar [18,19]. And the EVA is added to mortars and concrete to improve the bond strength and reduce the modulus of mortar elasticity, which also improves the ability to store energy at different temperatures [20–22]. The addition of EVA can prevent the occurrence of cracks and improve the impact resistance, so that the bending strength and the toughness are improved [8,14,23]. In the hydration process, the acetic group of EVA copolymer consumes calcium hydroxide under basic condition to produce calcium acetate. The consumption of Ca2+ ions caused the capture of sulfate ions (SO2 4 ) in solution, retarding the nucleation and growth of AFt crystals [24,37], whereas methylcellulose has good water retention performance; these abilities will all improve the stability of AFt and ensure the later strength of the repair material [25–27]. EVA could improve the flexural strength and toughness of cement-based material [28], and methylcellulose could improve the stability of hydration products [29]. Therefore, the purpose of this study is to put forward the compressive and bending strength development of EVA- and methylcellulose-modified Portland cement-calcium aluminate cement-gypsum ternary mortar. The Pore structure at 28d was also measured. Meanwhile, the hydra-

The properties of the Portland cement (OPC, PO 42.5, provided by Conch Group Co., Ltd.) and calcium aluminate cement (CAC50, provided by Kerneos Cement Co.) are shown in Table 1. The gypsum (CaSO42H2O) used in this study were obtained from Kemiou chemical reagent Co. And the chemical compositions of the raw materials are shown in Table 2. The polymers adopted were redispersible powder on EVA (produced by Wacker Co.) and methylcellulose (3011C, provided by Shanghai Ziqi Biotechnology Co., Ltd.). The EVA solid content is 99%, apparent density is 495 g/l, Main particle size is 1–7 mm, and MFFT is 0 . The methylcellulose solid content is 99%, pH is 6.5, and volume density is 488 g/l. A standard silica sand with particle size of 0.5–1.0 mm and specific density of 2.69 g/cm3 was used. 2.2. Sample preparation The binder of mortar specimen was a mixture of OPC, CAC and gypsum, and the repair mortar of ternary system with different proportions was tested, and the results are shown in Table 5. The 

optimal ratio is 75%–20%–5% of OPC-CAC-CS, because this ratio has the highest strength. All mortar specimens were molded in the size of 40 mm  40 mm  160 mm with the water at a water-to-binder ratio of 0.35 and the sand at a sand-to-binder of 1.5 by weight were prepared, respectively EVA copolymers were mixed with cement with weight values of 0.5%, 1.0%, 1.5%, and 2.0%. Methylcellulose was mixed with cement with weight values of 0.05%, 0.10%, 0.15%, and 0.20%. The complex polymers were made of 1.5% EVA copolymer, with different dosages of methylcellulose (0.05%, 0.10%, 0.15%, and 0.20%). The mix design is shown in Table 3. The mixing system as the follows. (1) Homogenizing of drymixture Cement and other dry powder materials poured into a mixer, for 1 min. (2) Further mixing was done with water, for 3 min. (3) Transfer the stirred mortar into molds and vibrated for 1 min. The molds were removed after 2 h and the specimens were cured in water for 7 days at 20 ± 1 °C. After 7 days, the specimens were moved to normal environment for 28 days at 70% humidity and 20 ± 1 °C. All paste samples were molded with the water to binder ratio of 0.35 by weight were prepared and cured in the same conditions. They were broken into pieces and then terminated-hydrated in

Table 2 Chemical composition of OPC and CAC (% by weight).

OPC CAC

CaO

Al2O3

SiO2

Fe2O3

R2O

71.83 37.01

4.96 52.39

19.22 7.81

2.98 2.42

1.01 0.37

Table 1 Properties of OPC and CAC. Type of cement

specific surface area (m2/kg)

OPC CAC

348 369

Setting time (min)

Flexural strength (MPa)

Compressive strength (MPa)

Initial

Final

3d

28d

3d

28d

166 40

254 56

6.2 7.2

7.5 8.5

32.4 52.0

57.5 64.5

3

C. Shi et al. / Construction and Building Materials 241 (2020) 118035 Table 3 Mix design of composite (%). EVA

Methylcellulose

CAC

OPC

Gypsum

Blank E05 E10 E15 E20 M005 M010 M015 M020 EM005 EM010 EM015 EM020

0 0.5 1.0 1.5 2.0 0 0 0 0 1.5 1.5 1.5 1.5

0 0 0 0 0 0.05 0.10 0.15 0.20 0.05 0.10 0.15 0.20

20 20 20 20 20 20 20 20 20 20 20 20 20

75 75 75 75 75 75 75 75 75 75 75 75 75

5 5 5 5 5 5 5 5 5 5 5 5 5

Flexural strength(MPa)

Abbreviation

2

dtb bh

Wb ¼

Tb 2

bh

ð6Þ

ð7Þ

where f b is the equivalent bending strength (N/mm2), Wb is the equivalent bending toughness (KJ/m3), T b is the area under the load deflection curve (Nmm), dtb is the midspan deflection (mm) and L is the span (mm), h is section width of specimen (mm), b is height of specimen (mm). The cumulative pore volume and pore volume distribution of the ternary cement mortar via mercury intrusion porosimeter (MIP, Autopore, IV 9510, USA) with the ternary cement mortar aged for 28 day [32]. For intrusion a cylindrical pore model, the pore size d of specimen was calculated as the follows [33],

d¼

4ccosh P

1d 3d 7d 28d 0.0

0.5

1.0

1.5

2.0

13 12 11 10 9 8 7 6 5 4 3 2 1 0

(b)

1d 3d 7d 28d 0.00

0.05

0.10

0.15

0.20

Methylcellulose content (wt.%)

ð8Þ

where P is the intrusion pressure (Pa), where c is the surface tension of mercury of 0.485 N/m, and h is the contact angle contact angle of 130° [34]. The hydration mechanism of hydrated products were analyzed via X-ray diffraction (XRD, Model D/max-2400; Japan Rigaku Corporation) with Cu Ka radiation in the 2h range from 5° to 60°. And the hydrated microstructures were analyzed via scanning electron microcopy (SEM, Model FEI Quanta 200; Holland FEI Company, operated at 20 kV) [35]. 3. Results and discussion 3.1. Mechanical properties Fig. 1 shows the flexural strength of the repair mortar with different contents of EVA and methylcellulose. The flexural strength

Flexural strength(MPa)

T bL

Flexural strength(MPa)

2.3. Tests programs

f b¼

(a)

EVA powder content (wt.%)

the mixture of alcohol and acetone at 1, 3, 7, and 28 days. Afterward, they were dried for 48 h and then used for XRD and SEM tests.

The flexural strength and the compressive strength were tested according to EN 196-1. And the toughness (four-point bending, 4PB) of the specimen (40 mm  40 mm  160 mm) was conducted using Universal testing machine (Model CMT5105, MTS Systems Co., Ltd.). The loading rate was set up to 0.02 mm/min. The distance between the centers of the two load heads was 50 mm and the bottom supports span was 150 mm. The equivalent bending strength and equivalent bending toughness of specimen was calculated as the follows [30,31]:

13 12 11 10 9 8 7 6 5 4 3 2 1 0

13 12 11 10 9 8 7 6 5 4 3 2 1 0

(c)

1d 3d 7d 28d 0

1.5+0.05

1.5+0.10

1.5+0.15

1.5+0.20

Complex mixing content (wt.%) Fig. 1. The flexural strength of polymer modified ternary mortar samples: (a) EVA; (b) Methylcellulose; (c) EVA and Methylcellulose.

of EVA-modified mortars increased with increasing EVA powder content, and it increased to maximum when the EVA content was 1.5% (Fig. 1(a)). EVA is added to mortars and concrete to improve the bond strength and reduce the modulus of mortar elasticity [22], thereby increasing the flexural strength. Comparing blank samples in different curing ages, we found that the flexural strength decreases after curing for 28 days. This result is due to the decomposition of AFt [7,36], whereas with the incorporation of EVA, the flexural strength after 28 days was increased when

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C. Shi et al. / Construction and Building Materials 241 (2020) 118035

70

5000 BLANK

60

EVA1.5%

4000

50

3000 40

Load(N)

Compressive strength(MPa)

(a)

30 20

1d 3d 7d 28d

10 0

2000 1000 0

0.0

0.5

1.0

1.5

0.0

2.0

0.1

0.2

0.3

0.4

0.5

0.6

Deflection(mm)

EVA powder content (wt.%)

Fig. 3. Representative experimental load-displacement curves of ternary cement with or without EVA.

70

Table 4 Equivalent bending strength and equivalent bending toughness.

50

Equivalent bending strength (N/mm2) Equivalent bending toughness (KJ/m3)

40

1.5% EVA 5.32 4.16

0

0.60

1d 3d 7d 28d 0.00

0.05

0.10

0.15

0.20

Methylcellulose content (wt.%) 70

(c) 60 50

0.50 0.45 0.40 0.35 0.30

Blank E15 M010 EM010

0.25 0.20 0.15 0.10 0.05 0.00 101

40

102

103

104

105

Pore size Diameter (nm)

30 20

1d 3d 7d 28d

10 0

(a)

0.55

Cumulative Intrusion (mL/g)

20 10

Compressive strength(MPa)

0% EVA 4.06 3.71

30

0

0.6

1.5+0.05

1.5+0.10

1.5+0.15

1.5+0.20

Complex mixing content (wt.%) Fig. 2. The compressive strength of polymer modified ternary mortar samples: (a) EVA; (b) Methylcellulose; (c) EVA and Methylcellulose.

the EVA content was more than 1.5%. This result is due to the fact that the acetic group of EVA copolymer consumes calcium hydroxide under basic condition to produce calcium acetate. The consumption of Ca2+ ions caused the capture of sulfate ions (SO24 ) in solution, retarding the nucleation and growth of AFt crystals [37], thus the presence of AFt was fine and well-crystallized rod. With the incorporation of methylcellulose (Fig. 1(b)), the flexural strength decreased with increasing methylcellulose.

Log Differential Intrusion (mL/g)

Compressive strength(MPa)

(b) 60

(b)

0.5 0.4 0.3 Blank E15 M010 EM010

0.2 0.1 0.0 1 10

10

2

10

3

10

4

10

5

Pore size Diameter (nm) Fig. 4. Pore structure of ternary cement with EVA and Methylcellulose at 28 days: (a) cumulative porosity; (b) logarithmic differential pore volume distribution.

5

C. Shi et al. / Construction and Building Materials 241 (2020) 118035

However, the compressive strength has no reduction in the late age compared with different ages. As shown in Fig. 2(c), the compressive strength first increased then decreased and did not decrease after 28 days of curing when EVA powder and methylcellulose were added together in the preparation of the mortar. The optimal dosage is 1.5% EVA with 0.1% methylcellulose. After the combination of these two agents, the filling effect of EVA reduced the adverse air entraining effects caused by methylcellulose. Thus, the compressive strength did not decrease significantly when the content of methylcellulose was less than 0.1%. However, with increasing amount of methylcellulose, the amount of entrained air also increased, and the filling effect was not enough to counteract the adverse effect caused by the entrained air [39]. The compressive strength decreased. However, the water retention effects of methylcellulose still ensured the stability of AFt [14]. Thus, the compressive strength did not decrease after 28 days of curing.

Table 5 Mix proportions of the samples and relative measurements. Binder (PC: CAC:Gypsum)

Flexural strength (MPa)

Compressive strength (MPa)

1d

3d

7d

28d

1d

3d

7d

28d

77:20:3 75:20:5 72:20:8 70:20:10

4.13 4.52 5.66 6.05

6.30 6.61 7.35 7.15

8.45 9.22 9.31 9.18

7.02 7.35 7.18 6.99

20.35 25.42 26.00 28.34

38.55 43.65 42.10 41.18

55.36 57.23 56.00 55.50

52.04 53.35 53.30 51.18

Methylcellulose was found to have air entrainment during the mixing process, which resulted in a decrease in strength when the amount of methylcellulose was more than 0.1%. However, different from other samples, the strength did not decrease after 28 days of curing. This result is due to the fact that methylcellulose can enhance the stability of AFt by good water retention effect [16,38], which thereby ensuring the development of late strength. When the mortars were prepared with 1.5% EVA and methylcellulose, they showed an interaction phenomenon. As the methylcellulose increases, the flexural strength was first increased and then decreased. After 28 days of curing, it increased obviously with the methylcellulose increased. The content of methylcellulose was 0.1%, which was optimal (Fig. 1(c)). According to previous studies, EVA has a filling effect [28] that can offset the adverse effect of air entrainment by methylcellulose on the strength of the mortar. The water retention of methylcellulose improves the stability of AFt and ensures the development of late strength. However, when the content of methylcellulose is more than 0.1%, the filling effect of EVA is not enough to offset the air entraining effect; thus, the strength is decreased. Fig. 2 shows the compressive strength of the repair mortar with different modifiers. The compressive strength of mortars with EVA powder (Fig. 2(a)) are increased slowly when the content of EVA was less than 1.0% and then kept constant, but it decreased after 28 days of curing with EVA content of less than 1.5%. The compressive strength of the mortars decreased by a greater extent after the addition of methylcellulose (Fig. 2(b)), and with increasing methylcellulose, the intensity decreased more quickly. This result is due to air entrainment of methylcellulose during the mixing process.

E: ettringite, AFt H: portlandite, CH

3.2. Toughness Materials in engineering applications are subject to toughness. In this paper, the toughness was characterized equivalent bending strength and equivalent bending toughness. Fig. 3 shows the experimental load-displacement curves of the repair mortar with EVA0%, EVA1.5%. By calculation, the results of equivalent bending strength and equivalent bending toughness are shown in Table 4. The modified mortar with 1.5% EVA has better toughness, the equivalent bending strength increased by 31.03% and the equivalent bending toughness increased by 12.13%. There are three possible reasons as follows [37]: (a) the filling effect of EVA particles. (b) EVA is an elastic material which has good toughness. (c) The consumption of Ca2+ ions caused the capture of sulfate ions (SO24 ) in solution, retarding the nucleation and growth of AFt crystals. 3.3. Pore structure The mechanical properties of cement-based materials highly depend on the pore; thus, the mortar porosities were determined. The cumulative pore volume and pore volume distribution of the

M: monosulfate, AFm S: gympsum

C: calcium acetate

H M E

H H

S E

Blank C

E15

M010 C

EM010 5

10

15

20

25

30

35

40

45

50

Two-theta (degree) Fig. 5. The XRD of polymer modified ternary cement at 28 days.

55

60

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C. Shi et al. / Construction and Building Materials 241 (2020) 118035

(a1)

(a2)

(b1)

(b2)

(c1)

(c2)

(d1)

(d2)

Fig. 6. The SEM images of polymer modified ternary cement at 1 day and 28 days: (a1) blank ternary cement at 1 day; (a2) blank ternary cement at 28 days; (b1) with 1.5% EVA at 1 day; (b2) with 1.5% EVA at 28 days; (c1) with 0.1% Methylcellulose at 1 day; (c2) with 0.1% Methylcellulose at 28 days; (d1) with 1.5% EVA and 0.1% Methylcellulose at 1 day; (d2) with 1.5% EVA and 0.1% Methylcellulose at 28 days.

ternary cement mortar with 0% (Blank), 1.5% EVA (E15), 0.10% methylcellulose (M010), 1.5% EVA and 0.10% methylcellulose (EM010) after 28 days curing are shown in Fig. 4. As illustrated in Fig. 4(a), the cumulative pore volume was reduced by adding EVA of ternary cement mortar. As illustrated in Fig. 4(b), the pore volume of polymer-free pure mortar with pore diameter of 10 nm-1000 nm is higher than that of modified mortar with 1.5% EVA. With the hydration reaction of the ternary material,

the EVA polymer particles gradually gathered in the capillary pore to form a tight accumulation layer. Thus, the pore is gradually filled with hydration products and polymer particles, which decreased the porosity. Thus the compressive strength increased [40]. The pore volume of polymer-free pure mortar with pore diameter of 1000 nm–10000 nm is lower than that all of modified mortars. This result is due to air entrainment of polymer during the mixing process [41].

C. Shi et al. / Construction and Building Materials 241 (2020) 118035

3.4. XRD The XRD patterns of Blank, E15, M010, and EM010 samples with 0%, 1.5% EVA, 0.10% methylcellulose, 1.5% EVA and 0.10% methylcellulose after 28 days of curing are shown in Fig. 5. The crystalline hydration products Portlandite and AFt were detected. The diffraction peak at about 9.1° corresponds to AFt. The peak is strengthened at the XRD curves of E15, M010, and EM010 but not observed at the blank paste. The peak of calcium acetate appeared at the XRD curves of E15. This result is due to the acetic group of EVA copolymer consumes calcium hydroxide under basic condition to produce calcium acetate; thus forming fine AFt crystal. The water retention ability of methylcellulose can enhance the stability of AFt. Thus, the combination of EVA and methylcellulose can promote the formation and stability of AFt [24,42]. 3.5. Microstructure The SEM images of the ternary cement paste, with different kinds of modifiers hydrated for 1 day and 28 days are shown in Fig. 6. Fig. 6(a1) presents the SEM observations of pastes without polymer cured for 1 day. The needle-like AFt was evidently revealed to be intercalated into the gel to form a skeleton. The AFt is wellcrystallized, and the length is about 20 mm along the c axis. As shown in Fig. 6(a2), AFt was hardly found after curing for 28 days, because it decomposed into AFm. Fig. 6(b1) the microstructure of the paste incorporated with EVA after 1-day hydration. The AFt crystal has been refined, because the hydration products with polymers form a coating at the interface, which prevents the growth of coarse AFt crystals. The length of the AFt crystal along the c axis is only about 5 mm, and it is almost completely encapsulated or covered by other hydration products to form agglomerates. With the 28-day hydration (Fig. 6(b2)), some AFt decomposed into AFm, whereas others are still wrapped in the gel. Fig. 6(c1) shows the microstructure of methylcellulosemodified paste after 1-day hydration. Many AFt crystals can be seen to have grown in clusters, but more defects can be seen on the surface of the crystals after magnification. After hydration for 28 days, the structure is looser than other pastes. Caused by the large porosity, lowest mechanical strength of the samples mixed with methylcellulose was observed. Fig. 6d shows the microstructure of the paste incorporated with EVA and methylcellulose. The structure is denser than other pastes. The result is due to the some pores and microfractures are filled by EVA particles and the combination of EVA and methylcellulose can enhance the Well-formed grain and stability of AFt. Composite use of EVA powder and methylcellulose can increase the flexural strength and maintain the strong compressive strength after 28day curing. 4. Conclusions In this research, the effects of EVA and methylcellulose on the mechanical properties of Portland cement–calcium aluminate cement–gypsum ternary repair mortar are investigated. With EVA addition, the flexural strength and toughness are improved obviously, the crystal structure of hydration products is also optimized. The compressive strength of the mortar is decreased by the addition of methylcellulose, which increases the porosity of the system by entraining air during mixing. However, methylcellulose can ensure the development of late strength, because its water retention ability can improve the stability of AFt in the late age.

7

The flexural strength and compressive strength of ternary mortar can be effectively improved, and the late strength can be maintained by using EVA and methylcellulose together at the appropriate content. The hydration products of the ternary system with EVA and methylcellulose have filling effect, which can offset the disadvantage of air entraining by methylcellulose. CRediT authorship contribution statement Chen Shi: Supervision, Writing - original draft. Xiwen Zou: Investigation, Writing - review & editing. Ping Wang: Data curation, Software. Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgments The work was supported by National Natural Science Foundation of China (Program No. 51908451). References [1] G. Li, H. Xie, G. Xiong, Transition zone studies of new-to-old concrete with different binders, Cem. Concr. Compos. 23 (2001) 381–387. [2] L.L. Xu, P.M. Wang, G.F. Zhang, Formation of ettringite in Portland cement/calcium aluminate cement/calcium sulfate ternary system hydrates at lower temperatures, Constr. Build. Mater. 31 (2012) 347–352. [3] C. Evju, S. Hansen, Expansive properties of ettringite in a mixture of calcium aluminate cement, Portland cement and b-calcium sulfate hemihydrate, Cem. Concr. Res. 31 (2001) 257–261. [4] G. Kastiukas, X.M. Zhou, J. Castro-Gomes, et al., Effects of lactic and citric acid on early-age engineering properties of Portland/calcium aluminate blended cements, Constr. Build. Mater. 101 (2015) 389–395. [5] S. Nagataki, H. Gomi, Expansive admixtures (mainly ettringite), Cem. Concr. Compos. 5 (1998) 163–170. [6] X. Zhang, G.X. Li, Z.P. Song, Influence of styrene-acrylic copolymer latex on the mechanical properties and microstructure of Portland cement/Calcium aluminate cement/Gypsum cementitious mortar, Constr. Build. Mater. 227 (2019) 116666. [7] J.S. Qian, J.C. Yu, H.Q. Sun, et al., Formation and function of ettringite in cement hydrates, J. Chin. Ceram. Soc. 45 (2017) 1569–1581. [8] S.F. Liu, Y.N. Kong, T.T. Wan, et al., Effects of thermal-cooling cycling curing on the mechanical properties of EVA-modified concrete, Constr. Build. Mater. 165 (2018) 443–450. [9] B.G. Ma, Y. Peng, H.B. Tan, Effect of hydroxypropyl-methylcellulose ether on rheology of cement paste plasticized by polycarboxylate superplasticizer, Constr. Build. Mater. 168 (2018) 341–350. [10] Camille A. Issa, Joseph J. Assaad, Stability and bond properties of polymermodified self-consolidating concrete for repair applications, Mater. Struct. 50 (2017) 28. [11] B. Yuan, Y.G. Yang, Y.Q. Wang, et al., Self-healing efficiency of EVA-modified cement for hydraulic fracturing wells, Constr. Build. Mater. 146 (2017) 563– 570. [12] X.L. Qu, X.G. Zhao, Influence of SBR latex and HPMC on the cement hydration at early age, Constr. Build. Mater. 6 (2017) 213–218. [13] S. Saoula, K. Ait Mokhtar, S. Haddadi, E. Ghorbel, Improvement of the performances of modified bituminous concrete with EVA and EVA-waste, Phys. Procedia 2 (2009) 1319–1326. [14] C. Shi, X.W. Zou, P. Wang, Influences of ethylene-vinyl acetate and methylcellulose on the properties of calcium sulfoaluminate cement, Constr. Build. Mater. 193 (2018) 474–480. [15] Alexandra A.P. Mansur, Otávio Luiz do Nascimento, Herman S. Mansur, Physico-chemical characterization of EVA-modified mortar and porcelain tiles interfaces, Cem. Concr. Res. 39 (2009) 1199–1208. [16] D. Bülichen, J. Kainz, J. Plank, Working mechanism of methyl hydroxyethyl cellulose (MHEC) as water retention agent, Cem. Concr. Res. 42 (2012) 953– 959. [17] Edyta Spychal, The effect of lime and cellulose ether on selected properties of plastering mortar, Procedia Eng. 108 (2015) 324–441. [18] D.A. Silva, P.J.M. Monteiro, Hydration evolution of C3S-EVA composites analyzed by soft X-ray microscopy, Cem. Concr. Res. 35 (2005) 351–357. [19] A.M. Betioli, J. Hoppe Filho, M.A. Cincotto, et al., Chemical interaction between EVA and Portland cement hydration at early-age, Constr. Build. Mater. 23 (2009) 3332–3336.

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