The work of Powers and Brownyard revisited: Part 2

Powers and Brownyard [T.C. Powers, T.L. Brownyard, Studies of the physical properties of hardened Portland cement paste, Bull. 22, Res. Lab. of Portland Cement Association, Skokie, IL, U.S., 1948 reprinted from J. Am. Concr. Inst. (Proc.), 43, 1947, pp. 101–132, pp. 249–336, pp. 469–505, pp. 549–602, pp. 669–712, pp. 845–880, pp. 933–992. [1]] were the first to systematically investigate the reaction of cement and water and the composition of cement paste. In Part I to this paper, their work was recapitulated (Brouwers [H.J.H. Brouwers, The work of Powers and Brownyard revisited: Part 1, accepted for publication in Cem. Concr. Res. 34 (2004) 1697–1716 [2]]). Here, it will be demonstrated that their water retention data also enables the study of the molar reactions of the aluminate (C3A and C4AF) and sulphate phases. It follows that the C4AF most likely reacts with the C3S and/or C2S to form a Si containing hydrogarnet and portlandite. The remaining calcium silicates react to C–S–H (C1.7SH3.2 when saturated) and CH, as proposed in Part I [H.J.H. Brouwers, The work of Powers and Brownyard revisited: Part 1, accepted for publication in Cem. Concr. Res. 34 (2004) 1697–1716 [2]].The CS¯ seems to react exclusively with the C3A. In case of carbonation, both phases react to hemi-carbonate, mono-sulphate, ettringite and tetra calcium aluminate hydrate. The concept “degree of carbonation” is introduced to quantify the fraction of mono-sulphate that is carbonated. This enables the quantification of all four hydration products, which represents a principal innovation. Subsequently, using the molar reactions and known specific volumes of the crystalline hydration products, the specific volumes of non-evaporable water (νn) and gel water (νg) are determined. These values are in line with the values suggested by Powers and Brownyard [T.C. Powers, T.L. Brownyard, Studies of the physical properties of hardened Portland cement paste, Bull. 22, Res. Lab. of Portland Cement Association, Skokie, IL, U.S., reprinted from J. Am. Concrete Inst. (Proc.), 43, 1947, pp. 101–132, pp. 249–336, pp. 469–505, pp. 549–602, pp. 669–712, pp. 845–880, pp. 933–992. [1]], which were based on their shrinkage data, implying a successful coupling of the molar reactions and their original paste model.