Influence of limestone on the hydration of Portland cements

doi:10.1016/j.cemconres.2008.01.002

Cement and Concrete Research

Volume 38, Issue 6, June 2008, Pages 848-860

https://doi.org/10.1016/j.cemconres.2008.01.002 Get rights and content

Abstract

The influence of the presence of limestone on the hydration of Portland cement was investigated. Blending of Portland cement with limestone was found to influence the hydrate assemblage of the hydrated cement. Thermodynamic calculations as well as experimental observations indicated that in the presence of limestone, monocarbonate instead of monosulfate was stable. Thermodynamic modelling showed that the stabilisation of monocarbonate in the presence of limestone indirectly stabilised ettringite leading to a corresponding increase of the total volume of the hydrate phase and a decrease of porosity. The measured difference in porosity between the “limestone-free” cement, which contained less than 0.3% CO₂, and a cement containing 4% limestone, however, was much smaller than calculated.

Coupling of thermodynamic modelling with a set of kinetic equations which described the dissolution of the clinker, predicted quantitatively the amount of hydrates. The quantities of ettringite, portlandite and amorphous phase as determined by TGA and XRD agreed well with the calculated amounts of these phases after different periods of time. The findings in this paper show that changes in the bulk composition of hydrating cements can be followed by coupled thermodynamic models. Comparison between experimental and modelled data helps to understand in more detail the dominating processes during cement hydration.

Introduction

Portland–limestone cements are the most widely used cements in Europe. Two classes exist in EN 197-1 designated as CEM II/A-L and CEM II/B-L in which the maximum contents of limestone are 20 and 35% respectively. Besides these special classes, limestone is widely used in all other European common cement types as 0–5% minor additional constituents. The use of up to 5% ground limestone in Portland cement is also permitted by the Canadian cement standard since the early 1980s (CSA 1998 - CAN/CSA-A5) and in more than 25 other countries.

From the point of view of the hardened concrete, up to 5% limestone per mass of cement seems to have little effect on the short and long term macroscopic performance. Regarding mechanical properties, several studies have shown that the compressive strength is more or less the same, or slightly increased, this effect is usually attributed to the fine particle size distribution of the limestone, enhancing the hydration of the clinker by the filler effect, rather than its influence on the chemistry or the packing. The same trend is observed with the flexural strength and the drying shrinkage. As for durability issues, the behaviour of the material with respect to all major aggressive species (sulfates, chlorides, carbonation) and main pathologies (freezing-thawing, ASR, corrosion…) is the same as for limestone free concrete. Neither are the diffusion processes significantly modified: measured oxygen permeability and water sorption are more or less unchanged. Negative effects on the properties discussed above start to be observed when the amount of limestone per mass of cement exceeds 10-15%, such that the drop in the reactive clinker component results in significant physical modifications of the material. A good review on all these aspects can be found in Hawkins et al. [1].

At the low addition level of < 5%, some modification of the heat of hydration at early ages may be observed depending on the fineness of the limestone, and the long term heat flow is a bit lower than without limestone due to the smaller fraction of hydrating clinker.

The chemistry associated with the hydration process seems to be the area where the effects of limestone are observed, even at such low levels. Early in the 1990s, several studies showed that limestone seems to favour crystallization of monocarbonate rather than monosulfate [2], [3], [4], with the consequence of increasing the amount of ettringite [2]. The high affinity between calcium aluminate and carbonate phases to form monocarbonate had previously been reported by Feldman et al. [5] and Bensted [6]. Some studies therefore looked at the possible substitution of calcium sulfate with limestone. It has been shown that depending on the fineness of the ground clinker and the level of sulfate in the system, calcium sulfate can be replaced up to 25% by calcium carbonate without any modification of the properties of the system [6], [7], [8].

In this paper the hydration of two cements was investigated, an OPC containing < 0.3% CO₂ intermixed with 0 and 4% of limestone (equivalent to 1.7% CO₂). Thermodynamic modelling has been used to predict the composition of the liquid and solid phase in a hydrating Portland cement in the absence and presence of limestone in the cement.

Section snippets

Materials and methods

All experiments were carried out using the same Portland cement with and without limestone. Laboratory ground clinker was homogenized with gypsum (Fluka purum p.a.; previously ground in isopropanol to a mean particle size of 4μm). A part of the cement was blended with 4% of ground natural limestone (mean particle size: 4μm): PC4, while the other part was used without limestone addition (PC). The chemical compositions of the materials as given in Table 1 were determined by X-ray fluorescence

Modelling approach

When cement is brought into contact with water, rapidly soluble solids such as gypsum dissolve and come close to equilibrium with the pore solution. The clinker phases hydrate at various rates, continuously releasing Ca, Si, Al, Fe and hydroxide into the solution, which then precipitate as C–S–H, ettringite and other hydrate phases. The dissolution rates of the clinker phases may be considered to determine the amount of Ca, Al, Fe, Si, and hydroxide released into solution and thus to control

Heat evolution

Isothermal conduction calorimetry (Fig. 5) indicates the onset of the acceleration period at approx. 3h in both PC and PC4. The maximal heat evolution was observed for PC4 after 10h and for PC after 11h, indicating a slight acceleration of the cement hydration in the presence of finely ground calcite. This is due to the additional surface provided for the nucleation and growth of hydration products [23], [24]. Accordingly, the cumulative heat after 72h expressed per g clinker, is higher for the

Modelling and experimental results

Thermodynamic modelling of hydrated limestone blended cement PC4 predicts the presence of C–S–H, portlandite, traces of hydrotalcite, calcite, ettringite and monocarbonate (Fig. 3). In agreement with the calculations, experimentally C–S–H, portlandite, calcite, monocarbonate and ettringite could be identified by XRD and TGA in the hydrated samples.

The amounts of portlandite deduced by XRD and TGA agree well with the calculated quantities (Fig. 11). As previously noticed by comparing NMR and XRD

Conclusions

Blending of Portland cement with limestone was found to not only accelerate the initial hydration reaction but also to influence the hydrate assemblage of the hydrating cement pastes. Both thermodynamic calculations and experimental observations indicate that in presence of limestone monocarbonate instead of monosulfate is stable at room temperatures.

hermodynamic modelling shows that the stabilisation of monocarbonate indirectly also stabilises ettringite. This is calculated to lead to a

Acknowledgements

The authors would like to thank Holcim Group Support for the supply of clinker and limestone samples. Thanks are extended to G. Möschner (Empa) and H. Mönch (EAWAG) for support during the experiments and for the analysis of the solutions, to J. Kaufmann for the MIP and to D. Rentsch (Empa) for NMR measurements.

References (56)

B. Lothenbach et al.
Thermodynamic modelling of the hydration of Portland cement
Cem. Concr. Res.
(2006)
S.-Y. Hong et al.
Alkali binding in cement pastes. Part I. The C–S–H phase
Cem. Concr. Res.
(1999)
B. Lothenbach et al.
Thermodynamic modelling of the effect of temperature on the hydration and porosity of Portland cement
Cem. Concr. Res.
(2008)
T. Matschei et al.
Thermodynamic properties of Portland cement hydrates in the system CaO–Al₂O₃–SiO₂–CaSO₄–CaCO₃–H₂O
Cem. Concr. Res.
(2007)
T. Matschei et al.
The role of calcium carbonate in cement hydration
Cem. Concr. Res.
(2007)
J. Pera et al.
Influence of finely ground limestone on cement hydration
Cem. Conc. Comp.
(1999)
T. Matschei et al.
The AFm phase in Portland cement
Cem. Concr. Res.
(2007)
M.D. Andersen et al.
A new aluminium-hydrate species in hydrated Portland cements characterized by 27Al and 29Si MAS NMR spectroscopy
Cem. Concr. Res.
(2006)
D. Rothstein et al.
Solubility behavior of Ca-, S-, Al-, and Si-bearing solid phases in Portland cement pore solutions as a function of hydration time
Cem. Concr. Res.
(2002)
A. Goldschmidt
About the hydration theory and the composition of th eliquid phase of Portland cement
Cem. Concr. Res.
(1982)

B. Lothenbach et al.

A thermodynamic approach to the hydration of sulphate-resisting Portland cement

Waste Manage.

(2006)

R.B. Perkins et al.

Solubility of ettringite (Ca₆[Al(OH)₆]₂(SO₄)₃ ·26H₂O) at 5–75 °C

Geochim. Cosmochim. Acta

(1999)

S.J. Way et al.

Early hydration of a Portland cement in water and sodium hydroxide solutions: composition of solutions and nature of solid phases

Cem. Concr. Res.

(1989)

M. Michaux et al.

Evolution at early hydration times of the chemical composition of liquid phase of oil-well cement pastes with and without additives. Part I. Additive free cement pastes

Cem. Concr. Res.

(1989)

W. Ma et al.

Solubility of Ca(OH)₂ and CaSO₄·2H₂O in the liquid paste from hardened cement paste

Cem. Concr. Res.

(1992)

H.-J. Kuzel et al.

Hydration of C3A in the presence of Ca(OH)₂, Ca_SO₄·2H₂O and CaCO₃

Cem. Concr. Res.

(1991)

L. Chou et al.

Comparative study of the kinetics and mechanisms of dissolution of carbonate minerals

Chem. Geol.

(1989)

W.P. Inskeep et al.

An evaluation of rate equations for calcite precipitation kinetics at pCO₂ less than 0.01atm and pH greater than 8

Geochim. Cosmochim. Acta

(1985)

I. Baur et al.

Dissolution–precipitation behavior of ettringite, monosulfate, and calcium silicate hydrate

Cem. Concr. Res.

(2004)

V.L. Bonavetti et al.

Studies on the carboaluminate formation in limestone filler-blended cements

Cem. Concr. Res.

(2001)

T. Schmidt et al.

A thermodynamic and experimental study of the conditions of thaumasite formation

Cem. Concr. Res.

(2008)

S. Tsivilis et al.

The permeability of Portland limestone cement concrete

Cem. Concr. Res.

(2003)

S. Tsivilis et al.

An analysis of the properties of Portland limestone cements and concrete

Cem. Concr. Compos.

(2002)

T. Vuk et al.

The effects of limestone addition, clinker type and fineness on properties of Portland cement

Cem. Concr. Res.

(2001)

P. Hawkins et al.

The Use of Limestone in Portland Cement: a State-of-the-Art Review

(2003)

A.P. Barker et al.

The early hydration of limestone-filled cements

K. Ingram et al.

Carboaluminate reactions as influenced by limestone additions

W.A. Klemm et al.

An investigation of the formation of carboaluminates

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Influence of limestone on the hydration of Portland cements

Abstract

Introduction

Section snippets

Materials and methods

Modelling approach

Heat evolution

Modelling and experimental results

Conclusions

Acknowledgements

Cem. Concr. Res.

Cem. Concr. Res.

Cem. Concr. Res.

Cem. Concr. Res.

Cem. Concr. Res.

Cem. Conc. Comp.

Cem. Concr. Res.

Cem. Concr. Res.

Cem. Concr. Res.

Cem. Concr. Res.

Waste Manage.

Geochim. Cosmochim. Acta

Cem. Concr. Res.

Cem. Concr. Res.

Cem. Concr. Res.

Cem. Concr. Res.

Chem. Geol.

Geochim. Cosmochim. Acta

Cem. Concr. Res.

Cem. Concr. Res.

Cem. Concr. Res.

Cem. Concr. Res.

Cem. Concr. Compos.

Cem. Concr. Res.

The Use of Limestone in Portland Cement: a State-of-the-Art Review

The early hydration of limestone-filled cements

Carboaluminate reactions as influenced by limestone additions

An investigation of the formation of carboaluminates