Natalia Shlonimskaya

Recently, computer aided molecular design (CAMD) using an Inverse Quantitative Structure Property Relationship (I-QSPR) approach was demonstrated as an effective tool for identifying compounds that can significantly reduce the surface tension of water [1].  The present work focuses on validating the hypothesis that such designed compounds will also be active shrinkage reducers in portland cement applications since the newly identified I-QSPR compounds were targeted for their ability to reduce the surface tension of water, a primary consideration for shrinkage-reducing activity. By reducing the surface tension of the pore fluid, the SRA significantly reduces the magnitude of capillary stresses and shrinkage strains that occur as concrete loses moisture. Twelve chemicals were tested for their ability to inhibit shrinkage in Type I ordinary portland cement under both autogenous and drying conditions, as well as for their effect on set time, short-term and long-term hydration rate [2]. The 12 additives included two commercial SRAs, one active ingredient of a commercial admixture, two classified as potential SRA compounds based on the patent literature, five compounds newly identified by using I-QSPR, and two compounds used to establish the QSPR relationship. All five I-QSPR compounds performed competitively with commercial SRAs, with one compound, 2-Butylaminoethanol, being the strongest drying shrinkage inhibitor tested by a significant margin. Hydration data showed no support that shrinkage reduction could be due to delayed hydration. The newly identified shrinkage-reducing compounds can potentially provide additional options for use in portland cement concrete applications.  The study is currently being extended to look at the effect of these same compounds on early age strength development, air content, and the microstructure of hardened cement paste.

[1] H. M. Kayello, N. K. R. Tadisina, N. Shlonimskaya, J. J. Biernacki and D. P. Visoc Jr., An Application of Computer-Aided Molecular Design (CAMD) Using the Signature Molecular Descriptor – Part 1. Identification of Surface Tension Reducing Agents and the Search for Shrinkage Reducing Admixtures, J. Am. Ceram. Soc., 97(2), 365-377 (2014).

[2] N. Shlonimskaya, J. J. Biernacki, H. M. Kayello and D. P. Visoc Jr., An Application of Computer-Aided Molecular Design (CAMD) Using the Signature Molecular Descriptor – Part 2. Evaluating Newly Identified Surface Tension Reducing Substances for Potential Use as Shrinkage Reducing Admixtures, J. Am. Ceram. Soc., 97(2), 378-385 (2014).