The influence of sodium and potassium hydroxide on volume changes in cementitious materials

Prediction of self-desiccation in low water-to-cement ratio pastes based on pore structure evolution

“…(4), besides the pore radius, other quantities also need to be known when estimating the RH depression due to menisci formation, namely the molar mass, the density, the surface tension and the contact angle of the solution. These parameters are usually assumed as for pure water in calculations, i.e., M w = 0.01802 kg/mol, ρ w = 1000 kg/m 3 , and γ w = 0.073 N/m [2,5,37]. In this paper, an attempt is made to assess the influence of the pore solution composition on these properties.…”

“…(6). Again, different values of this parameter have been assumed in the literature [5,27,37]. Shi and Winslow [40] intruded mercury at known pressures into cylindrical holes of known diameter (150-1000 μm) drilled in hardened cement paste samples and determined values of 121-139°.…”

“…The opinion of the authors is that at this moment there is insufficient information available for a quantitative model based on the disjoining pressure approach. In this paper, the approach based on capillary pressure has been followed, which is according to a number of authors [2,5,[15][16][17][18]37,39,44] the dominant mechanism of both autogenous shrinkage and drying shrinkage in the high RH range. The results demonstrate that this is perfectly adequate to predict the RH evolution with good accuracy.…”

Effect of Alkalis on Cementitious Materials:Understanding the Relationship between Composition, Structure, and Volume Change Mechanism

“…(2), for the elastic shrinkage, the high magnitude of shrinkage can be attributed to a high effective capillary pressure, degraded K , or increased K s . According to mercury intrusion porosimetry data, the porosity of OPC can be enlarged due to alkaline enrichment, resulting in a reduced K (Sant et al 2012). Based on nano-indentation tests, the elastic modulus of C-S-H aggregations can increase, probably resulting in an increased s K (Mendoza et al 2015).…”

“…For cementitious binders, the incorporation of alkalis, either released from the dissolving solid reagents or directly added by mixing solution, can have dramatic impacts on its hydration kinetics, hydrated phase assemblage, composition and nanostructure of main hydrated phase, i.e., calcium-silicate-hydrate (C-S-H) 1 ), pore solution chemistry, and early-age properties (Jawed and Skalny 1978). For instance, regarding the volumetric properties of ordinary portland cement (OPC) paste, the alkali incorporation can increase autogenous and drying shrinkage magnitudes but reduce shrinkage kinetics (Juenger and Jennings 2001;Sant et al 2012), and enhance micro-cracks formation. For alkali-activated calcium aluminosilicates (e.g.…”