Transport properties of concrete after drying-wetting regimes to elucidate the effects of moisture content, hysteresis and microcracking

Abstract Drying and wetting induce a number of microstructural changes that could impact transport properties and durability of concrete structures, but their significance is not well-established. This research examines pastes, mortars and concretes with different w/b ratios, binders, aggregate sizes, curing and conditioning regimes. 50 mm thick samples were dried to equilibrium at either 105 °C, 50 °C/7% RH, 21 °C/33% RH or gentle stepwise at 21 °C/93% RH → 3% RH, and then rewetted stepwise by humidification at 21 °C/33% RH → 86% RH and full saturation to produce varying degrees of damage and moisture content. Oxygen diffusivity and permeability, electrical conductivity, microcracking, accessible and total porosity were measured at different conditioning stages over 3-year period to better understand the effects of shrinkage, hysteresis and drying-induced damage on transport properties. The effect of supplementary cementitious materials (GGBS, SF) and implications of drying-wetting on concrete durability are discussed.

[1]  Nataliya Hearn,et al.  Self-sealing, autogenous healing and continued hydration: What is the difference? , 1998 .

[2]  RD Hooton,et al.  Permeability and Pore Structure of Cement Pastes Containing Fly Ash, Slag, and Silica Fume , 1986 .

[3]  Véronique Baroghel-Bouny,et al.  Water vapour sorption experiments on hardened cementitious materials. Part II: Essential tool for assessment of transport properties and for durability prediction , 2007 .

[4]  Floyd O. Slate,et al.  X-Rays for Study of Internal Structure and Microcracking of Concrete , 1963 .

[5]  Zoubeir Lafhaj,et al.  Experimental Study on a Mortar. Temperature Effects on Porosity and Permeability. Residual Properties or Direct Measurements Under Temperature , 2005 .

[6]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[7]  Hamlin M. Jennings,et al.  Structural Changes to the Calcium–Silicate–Hydrate Gel Phase of Hydrated Cement with Age, Drying, and Resaturation , 2008 .

[8]  Nick R. Buenfeld,et al.  Modelling the diffusivity of mortar and concrete using a three-dimensional mesostructure with several aggregate shapes , 2013 .

[9]  Kunio Matsui,et al.  Microstructural and bulk property changes in hardened cement paste during the first drying process , 2014 .

[10]  Y. F. Houst,et al.  Influence of porosity and water content on the diffusivity of CO2 and O2 through hydrated cement paste , 1994 .

[11]  Kenneth C. Hover,et al.  Influence of microcracking on the mass transport properties of concrete , 1992 .

[12]  N. Buenfeld,et al.  Influence of the interfacial transition zone and microcracking on the diffusivity, permeability and sorptivity of cement-based materials after drying , 2009 .

[13]  N. Buenfeld,et al.  Estimating the permeability of cement pastes and mortars using image analysis and effective medium theory , 2012 .

[14]  J. Mier,et al.  Effect of aggregates and microcracks on the drying rate of cementitious composites , 2008 .

[15]  Folker H. Wittmann,et al.  Role of disjoining pressure in cement based materials , 2005 .

[16]  N. Hearn.  Comparison of water and propan-2-ol permeability in mortar specimens , 1996 .

[17]  F. Glasser,et al.  Critical Examination Of Drying Damage To Cement Pastes , 2000 .

[18]  Lutz Franke,et al.  Influence of the age and drying process on pore structure and sorption isotherms of hardened cement paste , 2006 .

[19]  Zdenek P. Bazant,et al.  EFFECT OF CRACKING ON DRYING PERMEABILITY AND DIFFUSIVITY OF CONCRETE. , 1987 .

[20]  L. Wadsö,et al.  The influence of sorption hysteresis on diffusion coefficients represented with different moisture potentials , 2016 .

[21]  E. Gartner,et al.  A 1H NMR relaxometry investigation of gel-pore drying shrinkage in cement pastes , 2016 .

[22]  N. Buenfeld,et al.  Simulating the effect of microcracks on the diffusivity and permeability of concrete using a three-dimensional model , 2016 .

[23]  A. Caballero,et al.  A numerical and experimental study of aggregate-induced shrinkage cracking in cementitious composites , 2012 .

[24]  Hamlin M. Jennings,et al.  Refinements to colloid model of C-S-H in cement: CM-II , 2008 .

[25]  A. W. Harris,et al.  Mass transport properties of mature wasteform grouts , 2007 .

[26]  H. Reinhardt,et al.  Permeability and self-healing of cracked concrete as a function of temperature and crack width , 2003 .

[27]  Nick R. Buenfeld,et al.  Influence of drying-induced microcracking and related size effects on mass transport properties of concrete , 2015 .

[28]  F. O'Brien.  The Control of Humidity by Saturated Salt Solutions , 1948 .

[29]  N. Buenfeld,et al.  Effect of confining pressure and microcracks on mass transport properties of concrete , 2014 .

[30]  M. Carcasses,et al.  Gas permeability of concrete in relation to its degree of saturation , 1999 .

[31]  J. Sercombe,et al.  Experimental Study of Gas Diffusion in Cement Paste , 2007 .

[32]  A. Mullera,et al.  Use of Bench-top Nmr to Measure the Density, Composition and Desorption Isotherm of C-s-h in Cement Paste , 2013 .

[33]  A. Wexler,et al.  Relative humidity-temperature relationships of some saturated salt solutions in the temperature range 0 degree to 50 degrees C , 1954 .

[34]  Nataliya Hearn,et al.  Effect of Shrinkage and Load-Induced Cracking on Water Permeability of Concrete , 1999 .

[35]  W. Hansen,et al.  Effect of first drying upon the pore structure of hydrated alite paste , 1980 .

[36]  Chao-Lung Hwang,et al.  Drying shrinkage of portland cement pastes I. Microcracking during drying , 1984 .

[37]  I. Maruyama,et al.  Strain and crack distribution in concrete during drying , 2014 .

[38]  G. Scherer.  Drying gels: III. warping plate , 1987 .

[39]  Mickaël Thiery,et al.  A review and statistical study of existing hysteresis models for cementitious materials , 2014 .

[40]  L. Wadsö,et al.  Moisture diffusion coefficients of mortars in absorption and desorption , 2016 .

[41]  J.G.M. van Mier,et al.  Effect of aggregates on drying shrinkage microcracking in cement-based composites , 2002 .

[42]  Nick R. Buenfeld,et al.  Estimating the original cement content and water–cement ratio of Portland cement concrete and mortar using backscattered electron microscopy , 2013 .

[43]  R. Feldman,et al.  A model for hydrated Portland cement paste as deduced from sorption-length change and mechanical properties , 1968 .

[44]  G. Scherer.  Drying, Shrinkage, and Cracking of Cementitious Materials , 2015, Transport in Porous Media.

[45]  V. Baroghel-Bouny.  Water Vapour Sorption Experiments on Hardened Cementitious Materials: Part I: Essential Tool for Analysis of Hygral Behaviour and its Relation to Pore Structure , 2007 .

[46]  L. Nilsson.  Long-term moisture transport in high performance concrete , 2002 .

[47]  G. Sant,et al.  Quantitative discrimination of the nano-pore-structure of cement paste during drying: New insights from water sorption isotherms , 2015 .

[48]  L. Franke,et al.  Inkbottle Pore-Method: Prediction of hygroscopic water content in hardened cement paste at variable climatic conditions , 2006 .

[49]  Falk K. Wittel,et al.  Contraction gradient induced microcracking in hardened cement paste , 2011, 1509.04964.

[50]  Carola Edvardsen,et al.  Water Permeability and Autogenous Healing of Cracks in Concrete , 1999 .

[51]  B. Lothenbach,et al.  Supplementary cementitious materials , 2011 .

[52]  Hamlin M. Jennings,et al.  Observations of microcracking in cement paste upon drying and rewetting by environmental scanning electron microscopy , 1996 .

[53]  Zdeněk P. Baǎnt,et al.  Effect of cracking in drying and shrinkage specimens , 1982 .