Microstructure engineering of Portland cement pastes and mortars through addition of ultrafine layer silicates

Abstract Pozzolanic submicron-sized silica fume and the non-pozzolanic micron- and nano-sized layer silicates (clay minerals) kaolinite, smectite and palygorskite have been used as additives in Portland cement pastes and mortars. These layer silicates have different particle shape (needles and plates), surface charge, and size (micron and nano). The structure of the resulting cement pastes and mortars has been investigated by atomic force microscopy (AFM), helium porosimetry, nitrogen adsorption (specific surface area and porosity), low-temperature calorimetry (LTC) and thermal analysis. The main result is that the cement paste structure and porosity can be engineered by addition of selected layer silicates having specific particle shapes and surface properties (e.g., charge and specific surface area). This seems to be due to the growth of calcium-silicate-hydrates (C–S–H) on the clay particle surfaces, and the nano-structure of the C–S–H depends on type of layer silicate. The effect of layer silicate addition is most pronounced for palygorskite and smectite having the largest surface area and negative charges on the particle surfaces. The cement pastes containing palygorskite and bentonite have, in comparison to the pure cement paste and the paste containing kaolinite, a more open pore structure consisting of fine pores. Silica fume paste contains a significant amount of closed pores. As a secondary result, it is demonstrated that both the degree and duration of sample drying strongly modifies the structure of the cementitious materials under investigation.

[1]  C. Gallé,et al.  Effect of drying on cement-based materials pore structure as identified by mercury intrusion porosimetry: A comparative study between oven-, vacuum-, and freeze-drying , 2001 .

[2]  I. Odler.  The BET-specific surface area of hydrated Portland cement and related materials , 2003 .

[3]  R. Feldman.  Pore Structure Damage in Blended Cements Caused by Mercury Intrusion , 2006 .

[4]  S. Diamond.  Aspects of concrete porosity revisited , 1999 .

[5]  D. Winslow,et al.  The early evolution of the surface of hydrating cement , 1994 .

[6]  Jeffrey J. Thomas,et al.  A DISCUSSION OF THE PAPER "THE BET-SPECIFIC SURFACE AREA OF HYDRATED PORTLAND CEMENT AND RELATED MATERIALS" BY IVAN ODLER , 2004 .

[7]  E. Sellevold,et al.  Ice Formation in Hardened Cement Paste—1. Mature Water-Saturated Pastes , 1980 .

[8]  S. J. Gregg,et al.  Adsorption Surface Area and Porosity , 1967 .

[9]  H. Jennings,et al.  A model for two types of calcium silicate hydrate in the microstructure of Portland cement pastes , 2000 .

[10]  Emil Makovicky,et al.  Pozzolanic reactions of six principal clay minerals: Activation, reactivity assessments and technological effects , 1995 .

[11]  João M.P.Q. Delgado,et al.  Durability of Building Materials and Components , 1980 .

[12]  I. Richardson.  The nature of the hydration products in hardened cement pastes , 2000 .

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

[14]  Surendra P. Shah,et al.  EFFECTS OF CLAYS ON FRACTURE PROPERTIES OF CEMENT-BASED MATERIALS , 1993 .

[15]  Dale P. Bentz,et al.  Fibers, Percolation, and Spalling of High-Performance Concrete , 2000 .

[16]  Investigations on the aging of hydrated tricalcium silicate and portland cement pastes , 1995 .

[17]  Dale P Bentz,et al.  A three-dimensional cement hydration and microstructure program. I. hydration rate, heat of hydration, and chemical shrinkage , 1995 .

[18]  Changling He,et al.  Thermal stability and pozzolanic activity of raw and calcined mixed-layer mica/smectite , 2000 .

[19]  R. Feldman,et al.  Differentiation of interlayer and adsorbed water in hydrated portland cement by thermal analysis , 1971 .

[20]  S. Brunauer,et al.  Pore structures of hydrated calcium silicates and portland cements by nitrogen adsorption , 1970 .

[21]  L. Miljković,et al.  The1HT1 study of the influence of clay addition on Portland cement hydration , 1997 .

[22]  Karen L. Scrivener,et al.  Backscattered electron imaging of cementitious microstructures: Understanding and quantification , 2004 .

[23]  Sidney Diamond,et al.  Mercury porosimetry: An inappropriate method for the measurement of pore size distributions in cement-based materials , 2000 .

[24]  Paul E. Stutzman,et al.  Evolution of porosity and calcium hydroxide in laboratory concretes containing silica fume , 1994 .

[25]  S. Brunauer,et al.  Pore structure analysis by water vapor adsorption. III. Analysis of hydrated calcium silicates and portland cements , 1972 .

[26]  Dale P. Bentz,et al.  Influence of silica fume on diffusivity in cement-based materials: I. Experimental and computer modeling studies on cement pastes , 2000 .

[27]  Kenneth A. Snyder,et al.  Suspended hydration and loss of freezable water in cement pastes exposed to 90% relative humidity , 2004 .

[28]  E. J. Sellevold,et al.  Ice formation in hardened cement paste, Part II — drying and resaturation on room temperature cured pastes , 1986 .

[29]  I. Richardson,et al.  Microcrystalline calcium hydroxide in pozzalanic cement pastes , 1994 .

[30]  X. Cong,et al.  17O MAS NMR Investigation of the Structure of Calcium Silicate Hydrate Gel , 1996 .

[31]  Maria C.G. Juenger,et al.  The use of nitrogen adsorption to assess the microstructure of cement paste , 2001 .

[32]  Dirch H. Bager,et al.  Ice formation in hardened cement paste, Part I — room temperature cured pastes with variable moisture contents , 1986 .

[33]  R. Feldman.  Application of the helium inflow technique for measuring surface area and hydraulic radius of hydrated portland cement , 1980 .

[34]  M. Geiker,et al.  On the interpretation of low temperature calorimetry data , 2007 .

[35]  Anne B. Abell,et al.  Mercury Intrusion Porosimetry and Image Analysis of Cement-Based Materials. , 1999, Journal of colloid and interface science.

[36]  Hamlin M. Jennings,et al.  A model for the microstructure of calcium silicate hydrate in cement paste , 2000 .

[37]  Daniel Quenard,et al.  Spalling and pore pressure in HPC at high temperatures , 2000 .

[38]  Kristian Dahl Hertz,et al.  Limits of spalling of fire-exposed concrete , 2003 .

[39]  Jørgen Skibsted,et al.  Hydration of Portland cement in the presence of clay minerals studied by 29Si and 27Al MAS NMR spectroscopy , 2003 .

[40]  D. Morgan.  Simultaneous DTA-EGA of minerals and natural mineral mixtures , 1977 .

[41]  Jeffrey J. Thomas,et al.  Deterioration of the nitrogen BET surface area of dried cement paste with storage time , 1996 .

[42]  I. Richardson.  Tobermorite/jennite- and tobermorite/calcium hydroxide-based models for the structure of C-S-H: applicability to hardened pastes of tricalcium silicate, β-dicalcium silicate, Portland cement, and blends of Portland cement with blast-furnace slag, metakaolin, or silica fume , 2004 .

[43]  M. J. Vold.  Differential Thermal Analysis , 1949 .

[44]  A. C. V. Coelho,et al.  Hydration of a Portland cement blended with calcium carbonate , 2000 .