Eco-efficient Cementitious System Consisting of Belite-Ye'elimite

Subscriber access provided by UNIV OF NEW ENGLAND ARMIDALE

Article

Eco-efficient cementitious system consisting of beliteye’elimite-ferrite cement, limestone filler, and silica fume Chen Li, Mengxue Wu, and Wu Yao ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.9b00702 • Publication Date (Web): 21 Mar 2019 Downloaded from http://pubs.acs.org on March 28, 2019

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Sustainable Chemistry & Engineering

Eco-efficient cementitious system consisting of belite-ye’elimite-ferrite cement, limestone filler, and silica fume Chen Li, Mengxue Wu, and Wu Yao*

Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, Tongji University, 4800 Cao’an Road, Shanghai, 201804, China

E-mail: [email protected] (W. Yao)

KEYWORDS

Eco-efficient cement, Belite-ye’elimite-ferrite cement, Limestone, Silica fume, Hydration, Thermodynamic modeling

ABSTRACT

One of the main concerns in the modern cement industry is on reducing the CO2 emissions. As an alternative binder of Portland cement, belite-ye’elimite-ferrite (BYF) cement can reduce the CO2 emission by over 20% due to its benefits concerning the chemical composition and industrial processing. This paper proposed a ternary cementitious system consisting of BYF cement, limestone filler, and silica fume. The ternary system containing 10% limestone and 5% silica fume showed higher compressive strength than the BYF cement, whilst the CO2 emission 1

ACS Paragon Plus Environment

ACS Sustainable Chemistry & Engineering 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

factor further reduced by ~13%. The effect of limestone and silica fume on the hydration was studied. It was found that the hydration reaction of limestone induced the formation of hemicarbonate and stabilized ettringite. This reaction formed dissolution rims around the limestone particles. At the early hydration ages, silica fume was bonded by aluminum hydroxide, forming aluminate silicate hydrate. During the hydration, the silicate dissolved and reacted with the hydration products in the dissolution rims of limestone. This reaction increased the Si content in the rims, and may potentially contribute to the compressive strength development of the ternary cementitious system.

INTRODUCTION

Reducing the CO2 emissions and increasing the sustainability of the materials have become one of the major concerns in the modern cement industry

1-2.

It is not only related to industrial

production but also closely related to cement chemistry. A recent study proposed that developing new cementitious systems and innovative use of currently applied materials can be the most important and viable solutions to this issue 3.

Belite-ye’elimite-ferrite (BYF) cement is developed as an eco-efficient cementitious material in recent years

1, 3-5.

Its manufacture has a two-fold benefit compared to Portland cement. BYF

cement clinker consists mainly of belite (C2S) and ye’elimite (C4A3S), supplemented by some ferrite phase (C2(A,F)). From the perspective of cement chemistry, these mineral components require lower CaO content in the raw mix and generate less CO2 emissions derived from the decomposition of limestone

1, 4-5.

Regarding the industrial production, BYF cement clinker 2


Page 2 of 36

Page 3 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


requires a lower calcining temperature and shows better grindability

6-7.

The manufacturing

process thus requires less fuel energy and produces less fuel-related emissions. As a whole, BYF cement can save 20% to 40% CO2 emissions compared to Portland cement 1, 8-9.

Ye'elimite usually shows fast reaction kinetics with water. This reaction forms ettringite (C6AS 3H32)

and aluminum hydroxide (AH3) in the existence of calcium sulfate, or monosulfate (C4AS

H12) and aluminum hydroxide in its absence

9-11.

Compared with belite, the CaO content in

ye'elimite is even lower. This potentially indicates that calcium sulfoaluminate (CSA) cement, which contains higher ye'elimite content than BYF cement, can produce even lower CO2 emissions concerning the chemical composition. However, the aluminum sources, usually bauxite, in the raw mix are much less economical than the silicate sources 1, 4. Therefore, CSA cement is typically manufactured for special use, e.g., rapid hardening, expansion, and shrinkage compensating

4, 12.

In BYF cement, the ye’elimite content is lower than that in CSA

cement and belite accounts for a much higher proportion. The hydration of belite proceeds much slower than ye’elimite

8-9, 13-14.

Therefore, BYF cement usually gains its compressive

strength in a similar manner to Portland cement.

Limestone consists mainly of calcite. It is traditionally classified as an inert filler in Portland cement system. It is produced merely by grinding without calcining, which is even more economical and eco-efficient than some supplementary cementitious materials (SCM), e.g., fly ash and ground granulated blast furnace slag reactive with aluminates

15-16,

1, 3.

Recent studies realize that limestone is

and thus its utilization with aluminate-containing cements or

SCMs is believed to be promising. In CSA cement, limestone takes nucleation effect at early hydration ages, which accelerates the hydration and shortens the setting time 3


15, 17-19.

It also


Page 4 of 36

reacts with monosulfate, forming hemicarbonate (C4AC0.5H12) or monocarbonate (C4ACH12) 16, 18, 20-22.

Therefore, moderate use of limestone powder in CSA cement usually improves the

compressive strength 15. In BYF cement, limestone may react similarly as in CSA cement due to the same reactive component, ye’elimite. However, the effect of limestone addition on the properties, e.g., mechanical properties, early-age hydration, and hydration phase assemblage, of BYF cement has not been widely reported.

Most SCMs are derived from industrial by-products. They can also contribute to reducing CO2 emissions of cement industry 23-26. The most studied SCM in the CSA cement system is fly ash 27-29.

It shows nucleation effect

27,

and the silica and alumina in fly ash are also reactive

However, the dissolution kinetics of fly ash is usually slow at ambient temperature

23.

29.

In the

CSA cement system, it is reported that blending up to ~15% fly ash does not significant impact the compressive strength of cement mortar at constant water to cement ratio, but significantly decreases the compressive strength at constant water to binder ratio even at the hydration age of 180 d 27, 29. Silica fume is the by-product of the silicon and ferrosilicon industry 30. It consists of highly amorphous silica and has a smaller particle size with much larger specific surface area than fly ash

23, 30.

In Portland cement system, it enhances the mechanical properties of

cement-based materials by a strong nucleation effect and pozzolanic reactivity and improves the durability by refining the pore structure

31-33.

However, the effects of silica fume in BYF

cement or CSA cement systems have not been well studied.

This paper proposed a cementitious system consisting of BYF cement, limestone filler, and silica fume. It is a combination use of a new cementitious system and currently applied materials that are believed to be sustainable and eco-efficient. This cementitious system showed 4


Page 5 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


improved compressive strength than BYF cement paste, potentially allowing an increased usage of limestone filler. The hydration process of this system was studied by isothermal calorimetry, X-ray diffractometry (XRD), and thermodynamic modeling. The hydration states of limestone and silica fume were observed by scanning electron microscopy (SEM), which helps to understand the effect of silica fume on the hydration of limestone in this system.

EXPERIMENTAL

Materials and specimens. The BYF cement clinker was prepared following the procedures in 34.

Briefly, it was prepared from natural clay, bauxite, and chemical reagents including CaCO3,

Fe2O3, and CaSO4. H3BO3 was doped in the raw mix in order to stabilize belite at the E!H polymorph. The clinker was calcined in a high-temperature furnace at the temperature of 1300 °C for 1 h and cooled to room temperature by forced air convection. After calcining, the clinker was ground until passing through a 75 G' sieve and mixed with anhydrite (purity > 97.0%) by a mass ratio of 95:5 to obtain the BYF cement. Limestone powder (calcite) was a chemical reagent containing > 99.0% CaCO3. The chemical composition of BYF cement clinker and silica fume is shown in Table 1. The mineralogical composition of BYF cement clinker was tested by X-ray diffractometry (XRD) and Rietveld refinement with corundum as internal standard substance (Table 2). The particle size distribution of the materials was tested by laser particle size analyzer (Figure 1).

Table 1. Chemical composition of BYF cement clinker and silica fume (wt %)

Na2O MgO Al2O3

BYF cement clinker

Silica fume

0.17 0.21 26.92

0.37 0.32 0.20

5



SiO2 P 2O 5 SO3 K 2O CaO TiO2 Fe2O3 LOI

14.53 0.09 3.53 0.69 46.30 1.06 6.01 0.19

97.66 0.13 ~0 0.14 0.34 ~0 0.06 0.76

Table 2. Mineralogical composition of BYF cement clinker (wt %) Component

Chemical formula

Content

Belite -E!H) Ye’elimite Ferrite Aluminate Mayenite Gehlenite ACna

C2S

30.4 29.2 1.7 5.0 2.3 6.1 25.4

C4A3S C4AF C3A C12A7 C2AS

a

ACn refers to “Amorphous and Crystalline not-quantified” in XRD Rietveld refinement, which was reported to be ~25% in laboratory prepared BYF cement 35. 6 /%

(a)

Anhydrite Limestone

4

Slica fume 2

0 0.01

0.1

1 10 Diameter / µm

100

1000

Cumulate Volume / %

100 BYF clinker

Differential Volume

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 6 of 36

BYF clinker

(b)

Anhydrite

80

Limestone 60

Slica fume

40 20 0 0.01

0.1

1 10 Diameter / µm

100

1000

Figure 1. Particle size distribution: (a) differential volume fraction and (b) cumulative volume fraction.

Seven series of cementitious systems were studied. BYF cement was used as a reference system (marked as Ref). Binary and ternary systems were then built by replacing BYF cement with limestone and/or silica fume. They were marked by the mass percentage and type of the replacement as 5LS, 10LS, 15LS, 5SF, 5SF5LS, and 5SF10LS, where LS and SF represent

6


Page 7 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


limestone and silica fume, respectively. The dosage rate of silica fume was fixed at 5% because higher rates usually cause significant rheology problem to the fresh cement paste due to the high specific surface area of silica fume 30. Cement paste specimens were prepared at the water to binder ratio of 0.3. This water to binder ratio may be more suitable for evaluating the performance of cement-based materials that are specially designed for high-strength applications using low water to binder ratios.

Test methods. Isothermal calorimetry was first conducted on a TAM Air calorimeter to study the early-age hydration properties. The calorimeter was operated at 20 °C. The water to binder ratio of 0.4 was chosen for the isothermal calorimetry in order to make the cement paste more easily-mixed. Cement paste was mixed by spatula in ampoules outside the calorimeter for 2 min before testing. Small piece of wax papers were used to move all the paste on the spatula into the ampoules and the wax papers were put inside the corresponding ampoules before testing. Compared with the internal mixing method, the external mixing method used here may impact the earliest exothermic peak induced by dissolution and fast reactions 36. However, these disturbances can be minimized by skilled and quick operations.

The specimens for testing the compressive strength were cast in 20 mm cubic molds. They were demolded after the 1st day and cured under the conditions of 20°C ± 1°C, relative humidity > 95%. The compressive strength was tested at the age of 3 d, 7 d, 28 d, and 60 d, using the average of six specimens at each hydration age. After testing, the specimens were soaked in ethanol alcohol and then dried at 40°C to stop the hydration. Powder specimens were prepared for XRD and non-evaporable water contents whilst small pellets for SEM. All the samples were treated strictly following the same drying procedure in order that the results can 7



Page 8 of 36

be comparable and reproducible.

The non-evaporable water content was tested by calcining about 2 g specimens in a high-temperature furnace to 1000 °C. The results were normalized to 100 g binders (BYF cement + limestone + silica fume) and 100 g BYF cement according to Equation 1 and Equation 2, respectively.

=

40

(1

)

1000

(1)

1000

(2)

=

where Wn(b) and Wn(c) are the non-evaporable water content normalized to 100 g binder and 100 g cement, respectively; M40 and M1000 are the mass of the specimen before and after calcining; fC, fLS, and fSF are the mass fraction of BYF cement, limestone, and silica fume, respectively; LOIC, LOILS, and LOISF are the loss on ignition of BYF cement, limestone, and silica fume, respectively. The LOILS is assumed to be 0.44, which indicates that the decomposition of carbonates from limestone was excluded from the non-evaporable water content.

In order to quantify the type and amount of the hydration products, the specimens at the ages of 3 d and 60 d were tested by XRD on a type D/max2550VB3+/PC diffractometer. The scanning range of %S was from 5° to 75° (Cu KE radiation). The step and counting time were 0.02° and 2 s, respectively. Rietveld refinement was conducted by TOPAS Academic V5, using corundum (purity > 99.99%) as the internal standard substance. More details concerning the Rietveld refinement are provided in Supporting Information. 8


Page 9 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


The hydration states of limestone and silica fume were analyzed by SEM. The specimens in small pellets were sealed in epoxy resin, polished, and carbon coated. The tests were conducted on a Quanta 200 FEG microscope equipped with energy dispersive X-ray spectrometry (EDS), using the backscattered electron mode.

Thermodynamic modeling. The phase assemblage at equilibrium states was calculated by thermodynamic modeling using geochemical code GEMS 3.3

37

with the CEMDATA 18

database 38. The hydration degrees of the mineral components of BYF cement were assumed to be the same as those of the reference cementitious system at the age of 60 d: belite = 36%, ye’elimite = 86%, ferrite = 73%, aluminate = 35%, mayenite = 95%, gehlenite = 36%, anhydrite = 100%. The Na2O and K2O in the BYF cement and silica fume were assumed to dissolve entirely. The ACn in the BYF cement clinker was assumed to have the same composition as the XRD-crystalline phases. The water to binder ratio was assumed to be 0.5 in order to provide enough water and simulate the equilibrium state. The additions of limestone and silica fume were mimicked by replacing BYF cement with CaCO3 or SiO2. Both limestone and silica fume are considered free to react. The solid solutions of ettringite and monosulfate were not considered. Siliceous hydrogarnet (C3AS0.8H4.4) and thaumasite were suppressed because their formations usually show slow kinetics at ambient temperature 39.

RESULTS AND DISCUSSION

Early-age hydration heat. The heat flow curve of BYF cement exhibits three main peaks after the induction period, as shown in Figure 2. Compared with the reference series, the hydration kinetics of the binary cementitious system with limestone addition was accelerated. The

9



exothermic peaks, especially the second peak, appeared at earlier time, while the third peak became weaker. The 3-day cumulative heat was slightly higher than the reference, and 5% limestone replacement induced the highest cumulative heat. Silica fume accelerated the early hydration to a much greater extent than limestone. The first two peaks were much stronger, the second peak occurred even earlier, while the third peak was even weaker. The cumulative heat also increased significantly. In the ternary cementitious system, the heat flow curve did not show significant differences compared with the BYF cement–silica fume binary system. The cumulative heat at 3 d was lower than the binary system containing silica fume but was still higher than that of the BYF cement. 30

30

20

Ref 5LS 10LS 15LS

10

Cumulative 254.4 260.7 257.4 257.9

(b) Heat flow / mW·g-1

(a) Heat flow / mW·g-1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 10 of 36

0

Cumulative 254.4 266.2 261.1 259.4

20

Ref 5SF 5SF5LS 5SF10LS

10

0 0

120

240

360 480 Time /min

600

720

0

120

240

360 480 Time /min

600

720

Figure 2. Hydration heat flow between 0 and 720 min and cumulative heat (in J/g) at 3 d, normalized to binder content: (a) with limestone addition and (b) with silica fume addition.

When mixed with water, ye’elimite, anhydrite, and other aluminate-containing components dissolve, inducing a supersaturated solution with respect to ettringite

40.

After an induction

period, ettringite starts to precipitate. It has been reported that the hydration of ye’elimite in the existence of calcium sulfate includes two stages, thus forming two exothermic peaks

40.

The

dissolution of ye'elimite and gypsum can be observed synchronously with the precipitation of

10


Page 11 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


ettringite and aluminum hydroxide during the first peak. In contrast, neither the dissolution of gypsum nor the consumption of free water can be observed during the second peak. The surplus water in aluminum hydroxide and the absorbed sulfate on particles may serve as the water and sulfate sources for the precipitation of ettringite. After the consumption of sulfate, monosulfate starts to precipitate, which can also induce an exothermic peak as observed in some ye’elimite-containing cementitious systems

12, 15.

In contrast, the hydration of belite is usually

weak at the early hours 9. It may make a limited contribution to the heat flow curve. These existing findings can serve as potential interpretation of the heat flow curve.

The usage of fillers or SCMs can provide extra surfaces for the nucleation of hydration products. This effect accelerates the precipitation of the hydration products and is known as the “nucleation effect”

15, 23, 27.

Silica fume showed a much stronger nucleation effect than

limestone due to the much finer particle size. Moreover, replacing cement with inert fillers or lower-reactive SCMs also increases the available water for the cement to hydrate, thus prompting the hydration

27, 41.

However, both limestone and silica fume can be reactive in the

ye’elimite-containing cementitious systems (for silica fume, see

42-43).

Therefore, the increase

in the cumulative heat at 3 d age can result from the hydration of both BYF cement and those of limestone and/or silica fume.

Hydration phase assemblage. The hydration products in the hydrated cement paste were quantified by XRD, as shown in Figure 3. At 3 d age, ye’elimite hydrated to a relatively high level and calcium sulfate was depleted. As a result, both ettringite and monosulfate formed as the hydration products of ye’elimite (Reactions 3 and 4) 9-11.

11



Page 12 of 36

C4A3S + 2CS + 38H Y C6AS3H32 + 2AH3

(3)

C4A3S + 18H Y C4ASH12 + 2AH3

(4)

In contrast, belite hydrated to a much lower level and formed strätlingite (Reaction 5) 8-9, 13.

C2S + AH3 + 5H Y C2ASH8

(5)

Rietveld refinement indicates an amorphous content of ~50 g produced by the hydration of every 100 g binder. It is named as “Amorphous and Crystalline not-quantified” (ACn) in recent studies 29, 35, 44. This value agrees with the existing ones in hydrated BYF cement paste 8, 45, and may contain both amorphous products including unreacted silica fume and C-(A)-S-H, and the XRD-amorphous form of crystalline products including monosulfate, strätlingite, and aluminum hydroxide 29, 44-46. Limestone addition induced the formation of hemicarbonate at the expense of monosulfate, which showed a positive relationship with the limestone dosage rate. This can be expressed by the hydration reaction of limestone with ye’elimite as 17

6C4A3S + CC + 135H Y 2C4AC0.5H12 + 2C6AS3H32 + 14AH3 + 5CH

(6)

Besides, both limestone and silica fume additions benefitted the formation of ettringite. However, the ettringite amount kept almost the same at various dosage rates.

At the age of 60 d, belite, ye’elimite and limestone continued to dissolve. The ettringite content did not increase much, because the calcium sulfate had almost been depleted at 3 d. The contents of monosulfate and hemicarbonate also kept stable, but these products may continue forming in the XRD-amorphous form. The hydration of belite increased the content of strätlingite, and it did not show significant difference among different cementitious systems. Hydrogarnet was also detected in XRD. In the XRD patterns, the diffraction peaks

12


Page 13 of 36

corresponding to hydrogarnet locate between those of katoite (C3AH6) and hydrogrossular (C2.92AS1.1H3.8), which may indicate the co-existence of both phases or a solid solution between them (for more details, see Supporting Information). By dosing limestone and/or silica fume, the content of hydrogarnet decreased significantly.

120 140

120 140 ACn

120 100 Mass content g/100 g binder

80 60 40 20

Aluminium hydroxide

120 100

Strätlingite 80

Hydrogarnet Hemicarbonate

60

Monosulfate Ettringite

40

Calcite Other clinkers

20

0

Ye'elimite Belite

S 0L

(b)

5S

F1

F

LS F5

5S

5S

LS

S

f

LS

15

10

5L

S 0L

LS

(a)

5S

F1

F 5S

5S

F5

LS 15

S

LS 10

5L

Re

f

0

Re

Mass content g/100 g binder

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 3. Hydration products tested by XRD and Rietveld refinement, normalized to 100 g unreacted binder: (a) 3 d and (b) 60 d. Hydrogarnet is refined using the crystallographic models of both silica-free hydrogarnet (katoite) and siliceous hydrogarnet (hydrogrossular), and the results represent the sum of the two minerals.

In addition to the test results, an equilibrium hydration system was built based on the hydration degree of BYF cement at 60 d age, and the equilibrium phase assemblage was calculated (Figure 4). In the hydrated BYF cement paste (zero points of Figure 4a and 4b), ettringite, monosulfate, strätlingite, and aluminum hydroxide were all predicted to be stable, which agrees with the XRD. However, hydrogarnet is not predicted to form in the equilibrium system, though it was detected in the hydrated cement paste by XRD. In the C4A3S-C2S-CS-H equilibrium system, hydrogarnet usually forms at low calcium sulfate content by the hydration 13



Page 14 of 36

of belite 9, 47.

9C2S + C2ASH8 Y 10C1.7SH4 + C3AH6

(7)

4.9C2S + 3C2ASH8 Y 4C1.7SH4 + 3C3AS1.3H3.4

(8)

Silica-free hydrogarnet (katoite) is thermodynamically unstable in the presence of sulfate and carbonate, but the incorporation of Si and Fe can increase their compatibility 48-50. As observed by XRD, calcium sulfate is mostly depleted by the early hydration of ye’elimite. Since a low water to binder ratio was used to prepare the cement paste, the mass transport may be slow due to the insufficient local water at late hydration ages. The hydration system may need a long time to reach the equilibrium state. As a result, hydrogarnet can form and remain stable as a result of local non-equilibrium. This can be one possible reason that induces the difference between an equilibrium hydrated system (thermodynamic modeling) and a real hydrated system (XRD). The other possible reason may be that the cementitious materials cannot fully hydrate under such low water to cement ratio. It is also reported that the decomposition kinetics of hydrogarnet depends on the type of sulfates and carbonates that co-exist. In the existence of gypsum, hydrogarnet decomposes at the highest kinetics, followed by the existences of calcite and ettringite

48.

This explains the phenomenon that limestone addition decreased the

hydrogarnet content significantly and more effectively than silica fume addition (Figure 3).

14


Page 15 of 36

Mass content / g per 100 g binder

120

(a) Aluminium hydroxide

100 Aqueous 80

Strätlingite Monocarbonate

60 Monosulfate

Ettringite

40 Unreacted clinkers

Limestone

20 10

5 10 15 11 21 31 Limestone dosage rate / %

Mass content / g per 100 g binder

120

(b)

Aluminium hydroxide 100

20 41

Aqueous

80

C-S-H Strätlingite

60

Monosulfate Ettringite

40 Unreacted clinkers 20 10

2.5 5 7.5 11 21 31 Silica fume dosage rate / %

120 Mass content / g per 100 g binder

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


10 41

(c) Aluminium hydroxide

100 Aqueous 80

C-S-H

Strätlingite Monocarbonate

60

Ettringite

40

Unreacted clinkers

Limestone

20 01

2.5 5 7.5 11 21 31 Silica fume dosage rate / %

10 41

Figure 4. Equilibrium phase assemblage calculated by thermodynamic modeling: (a) BYF cement with limestone replacement, (b) BYF cement with silica fume replacement, and (c) BYF cement with 5% limestone replacement and various silica fume replacement.

As shown in Figure 4a, limestone addition stabilized monocarbonate and ettringite in favor of

15



Page 16 of 36

monosulfate.

3C4A3S + 2CC + 72H Y 2C4ACH11 + C6AS3H32 + 6AH3

(9)

Different from XRD where hemicarbonate was detected, monocarbonate is predicted to be thermodynamically stable. It has been proposed that kinetics of these reactions (Reactions 6 and 9) are governed by the dissolution of hemi- and monocarbonate. The formation of hemicarbonate is faster than that of monosulfate even when calcite is surplus 51. Similar results are also reported in the Portland cement system

51-52

and CSA cement system

15, 21.

When the

limestone dosage rate is higher than ~4.5%, all of the monosulfate destabilized, and limestone became chemically inert.

Blending a small amount of silica fume stabilized strätlingite and ettringite in favor of monosulfate and aluminum hydroxide (Figure 4b). This is similar to the effect of fly ash in the equilibrium phase assemblage of CSA cement system: It is reported that the silica and alumina in fly ash can react with monosulfate thus forming strätlingite and ettringite 27. In terms of silica fume, aluminum hydroxide that is produced by the hydration of ye’elimite can serve as the source of alumina. The reaction can be expressed as

3C4ASH12 + AH3 + 3S + 17H Y C6AS3H32 + 3C2ASH8

(10)

When the silica fume content exceeds ~4%, strätlingite destabilized thoroughly, forming C-S-H and aluminum hydroxide.

Figure 4c shows a ternary cementitious system containing 5% limestone replacement and 0– 10% silica fume replacement. Silica fume addition was predicted to destabilize monocarbonate and stabilize strätlingite, during which the reaction degree of limestone decreased continuously. 16


Page 17 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


When the silica fume dosage rate exceeds ~4%, C-S-H was stabilized in favor of strätlingite, with limestone becoming inert. However, neither the decomposition of hemicarbonate nor the reduction on the limestone reaction degree was observed in the XRD, though the silica fume dosage rate was 5%. This is probably caused by the different reaction kinetics between limestone and silica fume. It has been reported that the reaction of limestone occurs within the first day in the CSA cement system due to higher aluminate content than in the Portland cement system

15.

The dissolution kinetics of limestone is relatively fast under neutral to moderately

alkaline conditions but turns slower when the pH is above ~9 53-54. In contrast, the hydration of silica fume requires a relative high alkalinity

23.

Its hydration kinetics is slow within the first

day but accelerates as the alkalinity turns higher due to the hydration of cement

55-56.

These

facts indicate that the solution chemistry at the early hydration days may favor the hydration of limestone thus forming hemicarbonate. The hydration of silica fume may be delayed, and hemicarbonate may not decompose before the system reaches the final equilibrium.

Hydration states of limestone and silica fume. In order to figure out the hydration states of limestone and silica fume, the specimens were observed by SEM, and the results are illustrated in Figure 5. BYF cement clinker and limestone remained partially unreacted even at 60 d age. In contrast, silica fume had almost entirely dissolved at the age of 3 d. A few gel-like products were observed no matter when silica fume is dosed singly or in combination with limestone, as shown in Figure 5a. These products consisted mainly of Al, Si, and O. Based on ten EDS spots, the Al2O3 to SiO2 ratio varied from 0.25 to 1.5, and there was always extra bonding water in addition to Al2O3 and SiO2 according to the O content. To the best of the authors’ knowledge, similar products have not been reported elsewhere in BYF or CSA cement hydration systems,

17



but there was one similar result reported in the calcium aluminate cement system 57. Here, these products were named as aluminate silicate hydrates (A-S-H) according to their chemical composition. A few unreacted silica fume particles could be observed inside the A-S-H (Figure 5a, verified by EDS). It is thus proposed that the A-S-H is produced by the hydration reaction of silica fume with aluminum hydroxide. The A-S-H formed both large (Figure 5a) and small clusters at 3 d, but only small clusters could be observed at 60 d (Figure 5b). This phenomenon indicates that it has dissolved and reacted with other hydration products during the hydration process.

The hydration of limestone formed dissolution rims around the limestone particles (Figures 5c and 5d). It showed a darker contrast than the other hydration products and grew thicker with the hydration ages. A similar result was reported in the CSA cement system, showing that the hydration of fly ash also forms similar rims which consist mainly of aluminum hydroxide or a mix of hydration products showing dark contrast

27.

The chemical composition near the rims

was analyzed by EDS, as shown in Figures 5e and 5f. In the binary cementitious system with limestone addition (10LS), the spots located in the area representing a mixture of aluminum hydroxide, hemicarbonate, and ettringite. It cannot be confirmed whether monosulfate existed, but it is not a thermodynamically stable phase with limestone (Figure 4a). According to Reaction 6, the rims can be also treated as an area where the hydration reaction of limestone is taking place. Compared with the BYF cement–limestone binary system, the rims in the ternary cementitious system were not as clear (Figure 5d). A higher Si content was observed (Figure 5f), potentially indicating the existence of strätlingite contributed by the hydration of silica fume (Reaction 10). In addition to strätlingite, aluminum hydroxide and ettringite most

18


Page 18 of 36

Page 19 of 36

probably existed. Monosulfate and hemicarbonate might exist, but monosulfate was not thermodynamically stable.

Element Atom %

O Al Si Ca 75.3 13.1 10.3 1.2

10LS 5SF-10LS

0.4

(c)

(a)

Et

Ettringite

(e)

0.3 Aluminium hydroxide

2 Limestone

S/Ca

Silica fume

Ms 3

BYF clinker

1

1 3

2

2

0.1

1 Ettringite

0.2

Hc

Aluminium hydroxide

3 St

AH

0.0

BYF clinker

0.0

1.0

2.0

Al/Ca Element Atom %

O Al Si Ca 68.5 13.8 10.2 3.6

1.8

(b)

3

Ettringite

10LS 5SF-10LS

(d) 1.2

2

BYF clinker

C-A-S-H 3 1 St

0.6 Limestone

Ettringite

(f)

1

Aluminium hydroxide

Si/Ca

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


2 Aluminium hydroxide

BYF clinker

0.0

Et 0.0 Ms & Hc

3

2

1.0

1

AH 2.0

Al/Ca

Figure 5. Hydration states of limestone and silica fume observed by SEM: (a) 5SF at 3 d, (b) 5SF at 60 d and EDS spot analysis at “+”, (c) 10LS at 60 d with the spots 1, 2, and 3 tested by EDS, (d) 5SF10LS at 60 d with the spots 1, 2, and 3 tested by EDS, (e) and (f) EDS spots is the dissolution rims of limestone of 10LS and 5SF10LS at 60 d, where Et = ettringite, Ms = monosulfate, Hc = hemicarboaluminate, St = strätlingite, AH = aluminum hydroxide.

As discussed in the previous section, limestone is predicted to be inert in the equilibrium phase assemblage when the silica fume dosage rate exceeds ~4% in the ternary cementitious system (Figure 4c). However, the dissolution of limestone and the formation of hemicarbonate were observed by XRD (Figure 3). Combining the SEM observations, we proposed a model to express the hydration processes of limestone and silica fume, as shown in Figure 6. Limestone 19



starts to dissolve and reacts with ye’elimite from an early hydration time of ~1 d

Page 20 of 36

15.

This

reaction produces hemicarbonate, ettringite, and aluminum hydroxide, which form dissolution rims around the limestone (Figure 5c). Silica fume reacts with the aluminum hydroxide and forms A-S-H (Figure 5a) at the early hydration ages (before ~3 d), as marked by process and reaction (a) in Figure 6. A-S-H can be treated as an intermediate of the hydration of silica fume, and the final hydration is thus delayed. The hydration system does not reach the equilibrium state predicted in Figure 4c, and the formation of hemicarbonate is not significantly impacted, as shown in Figure 3a. As the hydration proceeds, the silicate in the A-S-H dissolves gradually (Figure 5b). One part of the silicate reacts with the monosulfate that is produced by the hydration of ye’elimite (Figure 4b), and the other with the hemicarbonate in the dissolution rims around the limestone (Figure 4c), as marked by the process (b) in Figure 6. Strätlingite thus forms in the dissolution rims (Figure 5f). This process may contribute to the mass transportation in this area, and thus the rims showed similar contrast compared to the other hydrated areas (Figure 5d). The formation of new hydration products may also strengthen the bonding between the unreacted limestone particles and the hydrated areas, thus taking a beneficial effect on the mechanical properties of the paste.

20


Page 21 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60




fume addition. It can be also inferred that although the hydration of silica fume formed an intermediate, A-S-H at early hydration ages, this reaction still makes a greater contribution to the entire amount of the hydration products than the hydration of limestone. In the ternary system, the non-evaporable water content was similar to the reference system at early hydration ages but lower at later ages. This phenomenon agrees with the effect of limestone addition in the binary cementitious system.

When normalized to 100 g BYF cement, both limestone and silica fume increased the non-evaporable water. This phenomenon verifies that they are both reactive in this system. In comparison, silica fume addition induced higher values than limestone addition at the same dosage rate. 3d per C 3d per B

35 Non-evaporable water /%

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

7d per C 7d per B

28d per C 28d per B

60d per C 60d per B

30 25 20 15 Ref

5LS

10LS

15LS

5SF

5SF5LS 5SF10LS

Figure 7. Non-evaporable water content normalized to 100 g binder (per B) and normalized to 100 g BYF cement (per C).

Compressive strength and eco-efficiency. The binary system with 5% limestone addition showed comparable compressive strength to the reference, and higher limestone dosage rates induced lower strength (Figure 8). In contrast, silica fume addition improved the compressive strength, especially at the early ages. The compressive strength of the binary systems agrees with the non-evaporable water content normalized to 100 g binder. These results indicate that 22


Page 22 of 36

Page 23 of 36

the entire amount of the hydration products plays a significant role in the compressive strength development. In the ternary system, the combination use of limestone and silica fume further improved the compressive strength, though the non-evaporable water content was slightly smaller. The ternary cementitious system containing 5% limestone and 5% silica fume showed the highest compressive strength, whilst that with 10% limestone and 5% silica fume also owned higher compressive strength than the BYF cement paste. According to the previous discussion, the delayed reaction of silica fume can impact the hydration products in the dissolution rims of limestone. This may benefit the microstructure in this area, which is probably responsible for the improvement on the compressive strength development.

Compressive strength / MPa

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


110

3d

7d

28d

60d

90 70 50 30 Ref

5LS

10LS

15LS

5SF

5SF5LS 5SF10LS

Figure 8. Compressive strength of cement paste at the water to binder ratio of 0.3.

In order to assess the eco-efficiency of the ternary cementitious system, we introduce the CO2 emission factor calculated by Reference 3. The emission factor (in tonne CO2 emission per tonne of material) of an ordinary Portland cement containing 10% limestone filler and 5% gypsum is 0.86, while that of BYF cement is 0.62–0.65. The emission benefits derive both from the ability to reduce raw-material-derived CO2 and from a less energy requirement for calcining and grinding during industrial processing. The CO2 emission in producing limestone filler mainly sources from grinding and transportation, and the emission factor is as low as 0.008.

23



The data of silica fume is not available in Reference 3. If it is considered as a by-product, only collection and transportation induces CO2 emission

58.

However, silica fume is less available

due to the large demand in cement industry, and it is still under debate whether the environmental impacts should be allocated in the cement industry 58. According to Reference 59, the emission factor of silica fume is approximately 0.12 considering the economic basis. Based on these data, the CO2 emission factor of the ternary cementitious system containing 10% limestone and 5% silica fume is about 0.55. Compared with BYF cement, the emission factor of the ternary cementitious system reduced by about 13%, but the compressive strength is still higher. By further optimizing the mix proportion, better mechanical properties and higher eco-efficiency can be also expected.

CONCLUSION

This paper developed a ternary cementitious system consisting of BYF cement, limestone filler, and silica fume, and studied the effect of limestone and silica fume on the hydration process and compressive strength development. Limestone shows a nucleation effect and accelerates the early-age hydration of BYF cement. It is reactive with ye’elimite, forming hemicarbonate at the expense of monosulfate. In the meanwhile, ettringite is stabilized whilst hydrogarnet is destabilized. This reaction forms dissolution rims showing a dark contrast around the unreacted limestone particles in SEM. Silica fume shows a much stronger nucleation effect than limestone. At an equilibrium hydration state, it stabilizes strätlingite and ettringite in favor of monosulfate. However, a reaction between silica fume and aluminum hydroxide takes place at the early hydration ages, which is indicated by the observation of gel-like products consisting mainly of A-S-H in SEM. The silicate in the A-S-H dissolves slowly, postponing the time for 24


Page 24 of 36

Page 25 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


the system to reach equilibrium. In the ternary cementitious system, the delayed-released silicate reacts with the hemicarbonate in the dissolution rims of limestone. A higher Si content was detected by EDS, and the dissolution rims seemed to have similar contrast to the other hydration areas. This effect may potentially strengthen the bonding between the unhydrated limestone particles and the hydration areas, and benefit the compressive strength development of the cement paste. The ternary system containing 5% silica fume and 10% limestone showed higher compressive strength than the BYF cement. It also provides a reduction on the CO2 emission factor by ~13%.

ASSOCIATED CONTENT

Supporting Information

The following files are available free of charge.

Rietveld refinement (PDF)

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Tel.: +86-21-69580141.

ORCID

Chen Li: 0000-0002-2071-7709

Mengxue Wu: 0000-0001-6850-3091

25



Author Contributions

The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript.

Notes

The authors declare no competing financial interest.

ACKNOWLEDGMENTS

This research was supported by the Open Fund of State Key Laboratory of Disaster Reduction in Civil Engineering (Grant No. SLDRCE18-05) and sponsored by the International Science and Technology Cooperation Projects of Shanghai (Contract No. 12230708700).

CEMENT NOTATION

A = Al2O3 C = CaO C = CO2 F = Fe2O3 H = H 2O S = SiO2 S = SO3

REFERENCES

1.

Scrivener, K. L.; John, V. M.; Gartner, E. M., Eco-efficient cements: Potential 26


Page 26 of 36

Page 27 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


economically viable solutions for a low-CO2 cement-based materials industry. Cem. Concr. Res. 2018, 114, 2-26, DOI 10.1016/j.cemconres.2018.03.015. 2.

Zhang, D.; Li, V. C.; Ellis, B. R., Optimal pre-hydration age for CO2 sequestration through

Portland cement carbonation. ACS Sustainable Chem. Eng. 2018, 6 (12), 15976-15981, DOI 10.1021/acssuschemeng.8b03699. 3.

Miller, S. A.; John, V. M.; Pacca, S. A.; Horvath, A., Carbon dioxide reduction potential in

the global cement industry by 2050. Cem. Concr. Res. 2018, 114, 115-124, DOI 10.1016/j.cemconres.2017.08.026. 4.

Gartner, E.; Hirao, H., A review of alternative approaches to the reduction of CO2

emissions associated with the manufacture of the binder phase in concrete. Cem. Concr. Res. 2015, 78, 126-142, DOI 10.1016/j.cemconres.2015.04.012. 5.

Gartner, E. M.; Macphee, D. E., A physico-chemical basis for novel cementitious binders.

Cem. Concr. Res. 2011, 41 (7), 736-749, DOI 10.1016/j.cemconres.2011.03.006. 6.

Wang, J. Hydration mechanism of cements based on low-CO2 clinkers containing belite,

ye'elimite and calcium alumino-ferrite. PhD, Université des Sciences et Technologie de Lille-Lille I, France, 2010. 7.

Li, G.; Walenta, G.; Gartner, E., Formation and hydration of low-CO2 cements based on

belite, calcium sulfoaluminate and calcium aluminoferrite. In Proceedings of the 12th ICCC, Montreal, Canada, 2007; pp 9-12. 8.

Álvarez-Pinazo, G.; Santacruz, I.; León-Reina, L.; Aranda, M. A. G.; De la Torre, A. G.,

Hydration reactions and mechanical strength developments of iron-rich sulfobelite eco-cements. Ind. Eng. Chem. Res. 2013, 52 (47), 16606-16614, DOI 10.1021/ie402484e.

27



9.

Page 28 of 36

Morin, V.; Termkhajornkit, P.; Huet, B.; Pham, G., Impact of quantity of anhydrite, water

to binder ratio, fineness on kinetics and phase assemblage of belite-ye'elimite-ferrite cement. Cem. Concr. Res. 2017, 99, 8-17, DOI 10.1016/j.cemconres.2017.04.014. 10. Juenger, M. C. G.; Winnefeld, F.; Provis, J. L.; Ideker, J. H., Advances in alternative cementitious

binders.

Cem.

Concr.

Res.

2011,

41

(12),

1232-1243,

DOI

10.1016/j.cemconres.2010.11.012. 11. Álvarez-Pinazo, G.; Santacruz, I.; Aranda, M. A. G.; De la Torre, Á. G., Hydration of belite–ye'elimite–ferrite cements with different calcium sulfate sources. Adv. Cem. Res. 2016, 28 (8), 529-543, DOI 10.1680/jadcr.16.00030. 12. Winnefeld, F.; Barlag, S., Calorimetric and thermogravimetric study on the influence of calcium sulfate on the hydration of ye’elimite. J. Therm. Anal. Calorim. 2009, 101 (3), 949-957, DOI 10.1007/s10973-009-0582-6. 13. Álvarez-Pinazo, G.; Cuesta, A.; García-Maté, M.; Santacruz, I.; Losilla, E. R.; Sanfélix, S. G.; Fauth, F.; Aranda, M. A. G.; De la Torre, A. G., In-situ early-age hydration study of sulfobelite cements by synchrotron powder diffraction. Cem. Concr. Res. 2014, 56, 12-19, DOI 10.1016/j.cemconres.2013.10.009. 14. Li, J.; Geng, G.; Zhang, W.; Yu, Y.-S.; Shapiro, D. A.; Monteiro, P. J., The Hydration of b&

E!H-Dicalcium Silicates: An X-ray Spectromicroscopic Study. ACS Sustainable Chem.

Eng. 2018, 7 (2), 2316-2326, DOI 10.1021/acssuschemeng.8b05060. 15. Pelletier-Chaignat, L.; Winnefeld, F.; Lothenbach, B.; Müller, C. J., Beneficial use of limestone filler with calcium sulphoaluminate cement. Constr. Build. Mater. 2012, 26 (1), 619-627, DOI 10.1016/j.conbuildmat.2011.06.065.

28


Page 29 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


16. Hargis, C. W.; Telesca, A.; Monteiro, P. J. M., Calcium sulfoaluminate (Ye'elimite) hydration in the presence of gypsum, calcite, and vaterite. Cem. Concr. Res. 2014, 65, 15-20, DOI 10.1016/j.cemconres.2014.07.004. 17. Martin, L. H.; Winnefeld, F.; Müller, C. J.; Lothenbach, B. In Influence of limestone on the hydration of calcium sulfoaluminate cements, Proceedings of the First International Conference on Sulphoaluminate Cement: Materials and Engineering Technology, WUT Press: 2013. 18. Martin, L. H. J.; Winnefeld, F.; Müller, C. J.; Lothenbach, B., Contribution of limestone to the hydration of calcium sulfoaluminate cement. Cem. Concr. Compos. 2015, 62, 204-211, DOI 10.1016/j.cemconcomp.2015.07.005. 19. Jeong, Y.; Hargis, C. W.; Chun, S.; Moon, J., Effect of Calcium Carbonate Fineness on Calcium

Sulfoaluminate-Belite

Cement.

Materials

(Basel)

2017,

10

(8),

DOI

10.3390/ma10080900. 20. Pedersen, M.; Lothenbac, B.; Winnefeld, F.; Skibsted, J., Hydrate Phase Assemblages in Calcium Sulfoaluminate–Metakaolin–Limestone Blends. In Calcined Clays for Sustainable Concrete, Springer: 2018; pp 352-357, DOI 10.1007/978-94-024-1207-9_57. 21. Winnefeld, F.; Lothenbach, B., Phase assemblages in hydrated calcium sulfoaluminate cements blended with mineral additions. In 34th Cement and Concrete Science Conference, Sheffild, UK, 2014. 22. Ma, J.; Yu, Z.; Ni, C.; Shi, H.; Shen, X., Effects of limestone powder on the hydration and microstructure development of calcium sulphoaluminate cement under long-term curing. Constr. Build. Mater. 2019, 199, 688-695, DOI 10.1016/j.conbuildmat.2018.12.054. 23. Lothenbach, B.; Scrivener, K.; Hooton, R. D., Supplementary cementitious materials. Cem.

29



Concr. Res. 2011, 41 (12), 1244-1256, DOI 10.1016/j.cemconres.2010.12.001. 24. Juenger, M. C. G.; Siddique, R., Recent advances in understanding the role of supplementary cementitious materials in concrete. Cem. Concr. Res. 2015, 78, 71-80, DOI 10.1016/j.cemconres.2015.03.018. 25. Miller, S. A., Supplementary cementitious materials to mitigate greenhouse gas emissions from concrete: can there be too much of a good thing? J. Clean. Prod. 2018, 178, 587-598, DOI 10.1016/j.jclepro.2018.01.008. 26. Li, C.; Wu, M.; Chen, Q.; Jiang, Z., Chemical and mineralogical alterations of concrete subjected to chemical attacks in complex underground tunnel environments during 20–36 years. Cem. Concr. Compos. 2018, 86, 139-159, DOI 10.1016/j.cemconcomp.2017.11.007. 27. Martin, L. H. J.; Winnefeld, F.; Tschopp, E.; Müller, C. J.; Lothenbach, B., Influence of fly ash on the hydration of calcium sulfoaluminate cement. Cem. Concr. Res. 2017, 95, 152-163, DOI 10.1016/j.cemconres.2017.02.030. 28. Ioannou, S.; Reig, L.; Paine, K.; Quillin, K., Properties of a ternary calcium sulfoaluminate–calcium sulfate–fly ash cement. Cem. Concr. Res. 2014, 56, 75-83, DOI 10.1016/j.cemconres.2013.09.015. 29. García-Maté, M.; De la Torre, A. G.; León-Reina, L.; Aranda, M. A. G.; Santacruz, I., Hydration studies of calcium sulfoaluminate cements blended with fly ash. Cem. Concr. Res. 2013, 54, 12-20, DOI 10.1016/j.cemconres.2013.07.010. 30. Siddique, R., Utilization of silica fume in concrete: Review of hardened properties. Resour. Conserv. Recycl. 2011, 55 (11), 923-932, DOI 10.1016/j.resconrec.2011.06.012. 31. Bentz, D. P.; Jensen, O. M.; Coats, A.; Glasser, F. P., Influence of silica fume on

30


Page 30 of 36

Page 31 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


diffusivity in cement-based materials: I. Experimental and computer modeling studies on cement

pastes.

Cem.

Concr.

Res.

2000,

30

(6),

953-962,

DOI

doi.org/10.1016/S0008-8846(00)00264-7. 32. Poon, C.-S.; Kou, S.; Lam, L., Compressive strength, chloride diffusivity and pore structure of high performance metakaolin and silica fume concrete. Constr. Build. Mater. 2006, 20 (10), 858-865, DOI 10.1016/j.conbuildmat.2005.07.001. 33. Wu, M.; Li, C.; Yao, W., Gel/space ratio evolution in ternary composite system consisting of Portland cement, silica fume, and fly ash. Mater. 2017, 10 (1), 59, DOI 10.3390/ma10010059. 34. Li, C.; Wu, M.; Yao, W., Effect of coupled B/Na and B/Ba doping on hydraulic properties of belite-ye’elimite-ferrite cement. Constr. Build. Mater. 2019, 208, 23-35, DOI 10.1016/j.conbuildmat.2019.02.163. 35. Álvarez-Pinazo, G.; Cuesta, A.; García-Maté, M.; Santacruz, I.; Losilla, E. R.; la Torre, A. G. D.; León-Reina, L.; Aranda, M. A. G., Rietveld quantitative phase analysis of Yeelimite-containing

cements.

Cem.

Concr.

Res.

2012,

42

(7),

960-971,

DOI

10.1016/j.cemconres.2012.03.018. 36. Scrivener, K.; Snellings, R.; Lothenbach, B., A practical guide to microstructural analysis of cementitious materials. Crc Press: 2016, DOI 10.1201/b19074. 37. Kulik, D. A.; Wagner, T.; Dmytrieva, S. V.; Kosakowski, G.; Hingerl, F. F.; Chudnenko, K. V.; Berner, U. R., GEM-Selektor geochemical modeling package: revised algorithm and GEMS3K numerical kernel for coupled simulation codes. Comput. Geosci. 2013, 17 (1), 1-24, DOI 10.1007/s10596-012-9310-6.

31



38. Lothenbach, B.; Kulik, D. A.; Matschei, T.; Balonis, M.; Baquerizo, L.; Dilnesa, B.; Miron, G. D.; Myers, R. J., Cemdata18: A chemical thermodynamic database for hydrated Portland cements and alkali-activated materials. Cem. Concr. Res. 2019, 115, 472-506, DOI 10.1016/j.cemconres.2018.04.018. 39. Dilnesa, B. Z.; Lothenbach, B.; Renaudin, G.; Wichser, A.; Kulik, D., Synthesis and characterization of hydrogarnet Ca3(AlxFe

f=)2(SiO4)y(OH) -:f 0.

Cem. Concr. Res. 2014, 59,

96-111, DOI 10.1016/j.cemconres.2014.02.001. 40. Jansen, D.; Spies, A.; Neubauer, J.; Ectors, D.; Goetz-Neunhoeffer, F., Studies on the early hydration of two modifications of ye'elimite with gypsum. Cem. Concr. Res. 2017, 91, 106-116, DOI 10.1016/j.cemconres.2016.11.009. 41. Li, C.; Zhu, H.; Wu, M.; Wu, K.; Jiang, Z., Pozzolanic reaction of fly ash modified by fluidized bed reactor-vapor deposition. Cem. Concr. Res. 2017, 92, 98-109, DOI 10.1016/j.cemconres.2016.11.016. 42. Chaunsali, P.; Mondal, P., Influence of mineral admixtures on early-age behavior of calcium sulfoaluminate cement. ACI Mater. J 2015, 112 (1), 59-68, DOI 10.14359/51687240. 43. Chaunsali, P.; Mondal, P., Physico-chemical interaction between mineral admixtures and OPC–calcium sulfoaluminate (CSA) cements and its influence on early-age expansion. Cem. Concr. Res. 2016, 80, 10-20, DOI 10.1016/j.cemconres.2015.11.003. 44. García-Maté, M.; Santacruz, I.; Cuesta, A.; León-Reina, L.; Aranda, M. A. G.; Baco, I.; Morin, V.; Walenta, G.; Gartner, E.; De la Torre, Á. G., Amorphous determination in calcium sulfoaluminate materials by external and internal methods. Adv. Cem. Res. 2015, 27 (7), 417-423, DOI 10.1680/adcr.14.00026.

32


Page 32 of 36

Page 33 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


45. Zajac, M.; Skocek, J.; Stabler, C.; Bullerjahn, F.; Ben Haha, M., Hydration and performance evolution of belite–ye'elimite–ferrite cement. Adv. Cem. Res. 2018, 1-14, DOI 10.1680/jadcr.18.00110. 46. Li, J.; Geng, G.; Myers, R.; Yu, Y.-S.; Shapiro, D.; Carraro, C.; Maboudian, R.; Monteiro, P. J. M., The chemistry and structure of calcium (alumino) silicate hydrate: A study by XANES, ptychographic imaging, and wide- and small-angle scattering. Cem. Concr. Res. 2019, 115, 367-378, DOI 10.1016/j.cemconres.2018.09.008. 47. Winnefeld,

F.;

Lothenbach,

B.,

Phase

equilibria

in

the

system

Ca4Al6O12SO4-Ca2SiO4-CaSO4-H2O referring to the hydration of calcium sulfoaluminate cements. RILEM Technical Letters 2016, 1, 10-16, DOI 10.21809/rilemtechlett.2016.5. 48. Okoronkwo, M. U.; Glasser, F. P., Compatibility of hydrogarnet, Ca3Al2(SiO4)x(OH)

-:f=0,

with sulfate and carbonate-bearing cement phases: 5–85 °C. Cem. Concr. Res. 2016, 83, 86-96, DOI 10.1016/j.cemconres.2016.01.013. 49. Geng, G.; Li, J.; Yu, Y.-S.; Shapiro, D. A.; Kilcoyne, D. A.; Monteiro, P. J., Nanometer-resolved

spectroscopic

study

reveals

the

conversion

mechanism

of

CaO·Al2O3·10H2O to 2CaO·Al2O3·8H2O and 3CaO·Al2O3·6H2O at an elevated temperature. Cryst. Growth Des. 2017, 17 (8), 4246-4253, DOI 10.1021/acs.cgd.7b00553. 50. Geng, G.; Myers, R. J.; Yu, Y.-S.; Shapiro, D. A.; Winarski, R.; Levitz, P. E.; Kilcoyne, D. A.; Monteiro, P. J., Synchrotron X-ray nanotomographic and spectromicroscopic study of the tricalcium aluminate hydration in the presence of gypsum. Cem. Concr. Res. 2018, 111, 130-137, DOI 10.1016/j.cemconres.2018.06.002. 51. Zajac, M.; Rossberg, A.; Le Saout, G.; Lothenbach, B., Influence of limestone and

33



anhydrite on the hydration of Portland cements. Cem. Concr. Compos. 2014, 46, 99-108, DOI 10.1016/j.cemconcomp.2013.11.007. 52. Lothenbach, B.; Le Saout, G.; Gallucci, E.; Scrivener, K., Influence of limestone on the hydration of Portland cements. Cem. Concr. Res. 2008, 38 (6), 848-860, DOI 10.1016/j.cemconres.2008.01.002. 53. Chou, L.; Garrels, R. M.; Wollast, R., Comparative study of the kinetics and mechanisms of dissolution of carbonate minerals. Chem. Geol. 1989, 78 (3-4), 269-282, DOI 10.1016/0009-2541(89)90063-6. 54. Inskeep, W. P.; Bloom, P. R., An evaluation of rate equations for calcite precipitation kinetics at pCO2 less than 0.01 atm and pH greater than 8. Geochim. Cosmochim. Acta 1985, 49 (10), 2165-2180, DOI 10.1016/0016-7037(85)90074-2. 55. Poulsen, S. L.; Jakobsen, H. J.; Skibsted, J. In Methodologies for measuring the degree of reaction in Portland cement blends with supplementary cementitious materials by 27Al and 29Si MAS NMR spectroscopy, IBAUSIL, 2009. 56. Hjorth, J.; Skibsted, J.; Jakobsen, H.,

29Si

MAS NMR studies of Portland cement

components and effects of microsilica on the hydration reaction. Cem. Concr. Res. 1988, 18 (5), 789-798, DOI 10.1016/0008-8846(88)90104-4. 57. Hidalgo Lopez, A.; García Calvo, J. L.; García Olmo, J.; Petit, S.; Alonso, M. C., Microstructural Evolution of Calcium Aluminate Cements Hydration with Silica Fume and Fly Ash Additions by Scanning Electron Microscopy, and Mid and Near Infrared Spectroscopy. J. Am. Ceram. Soc. 2008, 91 (4), 1258-1265, DOI 10.1111/j.1551-2916.2008.02283.x. 58. McLellan, B. C.; Williams, R. P.; Lay, J.; van Riessen, A.; Corder, G. D., Costs and carbon

34


Page 34 of 36

Page 35 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


emissions for geopolymer pastes in comparison to ordinary portland cement. J. Clean. Prod. 2011, 19 (9-10), 1080-1090, DOI 10.1016/j.jclepro.2011.02.010. 59. Heath, A.; Paine, K.; McManus, M., Minimising the global warming potential of clay based geopolymers. J. Clean. Prod. 2014, 78, 75-83, DOI 10.1016/j.jclepro.2014.04.046.

35




Page 36 of 36

Eco-efficient Cementitious System Consisting of Belite-Ye'elimite

Recommend Documents