Effect of pH on the durability of cement pastes

Revertégat, E.; Richet, Colette; Gégout, Philippe

doi:10.1016/0008-8846(92)90064-3

Cited by 130 publications

(52 citation statements)

References 3 publications

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“…In these studies leaching of calcium from cementitious materials have been accomplished both through immersion of the solid cementitious specimens in water (Faucon et al 1996;Haga et al 2005;Mainguy et al 2000) and through immersion of the specimens in chemical agents in order to accelerate the leaching process (Adenot and Buil 1992;Faucon et al 1996Faucon et al , 1998Haga et al 2005;Heukamp et al 2001;Mainguy et al 2000;Maltais et al 2004;Revertegat et al 1992;Ryu et al 2002;Saito et al 1992;Wittmann 1997). The results in these studies indicate that a layered structure is developed in the leached samples comprising an unaltered core delineated by total dissolution of Portlandite followed by different zones separated by dissolution/precipitation fronts and progressive decalcification of the CSH gel (Adenot and Buil 1992).…”

Section: Introductionmentioning

confidence: 99%

Physical and Mechanical Properties of Cementitious Specimens Exposed to an Electrochemically Derived Accelerated Leaching of Calcium

Babaahmadi

Tang

Abbas

et al. 2015

International Journal of Concrete Structures and Materials

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Simulating natural leaching process for cementitious materials is essential to perform long-term safety assessments of repositories for nuclear waste. However, the current test methods in literature are time consuming, limited to crushed material and often produce small size samples which are not suitable for further testing. This paper presents the results from the study of the physical (gas permeability as well as chloride diffusion coefficient) and mechanical properties (tensile and compressive strength and elastic modulus) of solid cementitious specimens which have been depleted in calcium by the use of a newly developed method for accelerated calcium leaching of solid specimens of flexible size. The results show that up to 4 times increase in capillary water absorption, 10 times higher gas permeability and at least 3 times higher chloride diffusion rate, is expected due to complete leaching of the Portlandite. This coincides with a 70 % decrease in mechanical strength and more than 40 % decrease in elastic modulus.

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Section: Introductionmentioning

confidence: 99%

Physical and Mechanical Properties of Cementitious Specimens Exposed to an Electrochemically Derived Accelerated Leaching of Calcium

Babaahmadi

Tang

Abbas

et al. 2015

International Journal of Concrete Structures and Materials

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“…For SO 4 , the primary processes include the formation of ettringite, thaumasite, and gypsum (Santhanam et al 2002). According to laboratory results presented by Revertegata et al (1992), low pH is related to leaching of Ca. Field studies dealing with the degradation of concrete have confirmed the combined effects of low pH and high SO 4 concentrations (Bellmann et al 2012).…”

Section: Cement-based Materialsmentioning

confidence: 94%

Hydrochemical impact of construction of the western section of the Hallandsås rail tunnel in Sweden

Mossmark

Annertz

Ericsson

et al. 2016

Bull Eng Geol Environ

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This paper presents a study of the hydrochemical changes that took place during construction of a section of the Hallandsås rail tunnel in southwest Sweden based on monitoring from spring 2011 to summer 2012. Leakage into the tunnel during construction caused lowering of the groundwater levels, which in turn resulted in a decrease in or absence of base flow in the streams. The water in the streams became dominated by meteoric water during the drawdown periods. Meanwhile, wetlands were aerated, and oxygen could penetrate to oxidise reduced S, releasing acids and SO 4 . The results for the groundwater in the bedrock differed spatially depending on local geological conditions. In each of the three monitored boreholes, higher redox potentials, higher concentrations of organic matter and lower concentrations of dissolved Mn and Fe were observed. In two of the boreholes, oxidation of pyrite, FeS 2 , present as a fracture mineral, caused the formation of SO 4 and acids with subsequent falls in pH and alkalinity. Leakage into underground constructions generally shortens the residence time of the groundwater significantly. Silicate weathering would thus become less important for the hydrochemistry compared to processes that occur during shorter time frames. As regards the durability of the tunnel, the hydrochemical changes observed in two of the three boreholes indicate a more aggressive environment for several parameters known to increase corrosivity of steel.The recovery of the groundwater levels occurred rapidly following completion of the waterproofing systems in the Tunnel. However, hydrochemical recovery with regard to major ions and pH occurred gradually and with an expected duration of several years.

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“…As sulfates ingress inwards, calcium hydroxide leaches out of the cement paste, releasing Ca 2+ and OH À , plus alkalis (Adenot and Buil, 1992;Kamali et al, 2003Kamali et al, , 2008Planel et al, 2006;Revertegat et al, 1992;Roziere and Loukili, 2011). This is plotted in Figure 2, where the extent of leaching shows a linear relationship with the square root of time, typical of diffusionbased reactions.…”

Section: Leachingmentioning

confidence: 99%

Current knowledge of external sulfate attack

Whittaker¹,

Black²

2015

Advances in Cement Research

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This paper offers an update of the current understanding of sulfate attack, with emphasis on the sulfates present in an external water source percolating through, and potentially reacting with, the cement matrix. The paper considers the explanations put forward to explain sulfate attack, both from a chemical and microstructural perspective.Similarly, this paper reviews work on the physical damage caused by the precipitation of sulfate salts in porous materials. With the increased use of binary and ternary blends, this paper also considers the impact of binder composition on sulfate resistance, and similarly reviews how the nature of the sulfate species can affect the nature and extent of any deterioration. This then leads on to the important consideration of differences between field-and lab-based studies, reviewing the effect of various experimental parameters on sulfate resistance. This latter topic is of great importance to anyone who wishes to carry out such experiments.

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Effect of pH on the durability of cement pastes

Cited by 130 publications

References 3 publications

Physical and Mechanical Properties of Cementitious Specimens Exposed to an Electrochemically Derived Accelerated Leaching of Calcium

Physical and Mechanical Properties of Cementitious Specimens Exposed to an Electrochemically Derived Accelerated Leaching of Calcium

Hydrochemical impact of construction of the western section of the Hallandsås rail tunnel in Sweden

Current knowledge of external sulfate attack

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