Pore structure of cement pastes through NAD and MIP analysis

Abstract

Two cement pastes (water to cement ratio, w/c = 0·5, 0·3) were investigated through mercury intrusion porosimetry (MIP) and nitrogen adsorption/desorption (NAD) methods at different hardening ages. The pore structure is characterised by specific surface area, pore volume and pore size distribution. The results show that: (a) the pore structure has strong scale dependence and NAD-MIP joint measurement helps to identify the different pore structure patterns; (b) MIP total pore volume captures the global process of the hydrates filling process with curing age, the mesopore (2-70 nm) volume is dominated by hydrates filling for w/c = 0·5 but countered by high-density calcium-silicate-hydrate growth for w/c = 0·3; (c) specific surface area is sensitive to calcium-silicate-hydrate growth and specific surface area values are likely to confirm that high w/c (0·5) favours low-density calcium-silicate-hydrate growth whereas low w/c (0·3) facilitates high-density calcium-silicate-hydrate formation.

Shrinkage and Mitigation Strategies to Improve the Dimensional Stability of CaO-FeOx-Al2O3-SiO2 Inorganic Polymers

“…NAD experiments record the adsorbed/desorbed nitrogen quantity as a function of the pressure imposed, allowing a deeper characterization of the structure of the powdered slags. Different evaluation methods—such as standard isotherms (t-plots), Langmuir, Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) [31]—have been proposed to evaluate NAD SSA values; the T-plot method was used herein.…”

Effect of pore structure on the performance of photocatalytic lightweight lime-based finishing mortar

“…The microstructure and porosity of mortar without TiO 2 additions are investigated with MIP (Thermo Fisher, Pascal series 240) and BET methods (Micrometics Tristar II). The pore size distribution is also investigated because some pore diameters are close to the dimension of nanoparticles that are applied in the mixes [44]. Both measurements are performed on samples after 28 days of curing, on three specimens and average values are used to interpret the results.…”

The efficiency of recycled glass powder in mitigating the alkali-silica reaction induced by recycled glass aggregate in cementitious mortars

“…The desorption branch cannot provide a reliable pore size distribution for a complex pore structure (such as cementitious materials) where network effects (pore-blocking and cavitation) significantly affect the desorption isotherm [58,59]. This method assumes pores in hydrated cement products to be cylindrical and has been utilised to investigate pore sizes up to 60 nm in radius [60][61][62]. Due to the assumption, the BJH method only provides limited information but is still reasonably effective in the qualitative analysis of cementitious materials [52,57,58], at least for comparative analysis.…”