Changes in portlandite morphology with solvent composition: Atomistic simulations and experiment

Porosity plays a clearly important role in geology. It controls fluid storage in aquifers, oil and gas fields and geothermal systems, and the extent and connectivity of the pore structure control fluid flow and transport through geological formations, as well as the relationship between the properties of individual minerals and the bulk properties of the rock. In order to quantify the relationships between porosity, storage, transport and rock properties, however, the pore structure must be measured and quantitatively described. The overall importance of porosity, at least with respect to the use of rocks as building stone was recognized by TS Hunt in his “Chemical and Geological Essays” (1875, reviewed by JD Dana 1875) who noted:

> “Other things being equal, it may properly be said that the value of a stone for building purposes is inversely as its porosity or absorbing power.”

In a Geological Survey report prepared for the U.S. Atomic Energy Commission, Manger (1963) summarized porosity and bulk density measurements for sedimentary rocks. He tabulated more than 900 items of porosity and bulk density data for sedimentary rocks with up to 2,109 porosity determinations per item. Amongst these he summarized several early studies, including those of Schwarz (1870–1871), Cook (1878), Wheeler (1896), Buckley (1898), Gary (1898), Moore (1904), Fuller (1906), Sorby (1908), Hirschwald (1912), Grubenmann et al. (1915), and Kessler (1919), many of which were concerned with rocks and clays of commercial utility. There have, of course, been many more such determinations since that time.

There are a large number of methods for quantifying porosity, and an increasingly complex idea of what it means to do so. Manger (1963) listed the techniques by which the porosity determinations he summarized were made. He separated these into seven methods for …

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Characterization and Analysis of Porosity and Pore Structures

Advances in understanding hydration of Portland cement

Technical and commercial progress in the adoption of geopolymer cement

Permafrost in steep bedrock is abundant in many cold-mountain areas, and its degradation can cause slope instability that is unexpected and unprecedented in location, magnitude, frequency, and timing. These phenomena bear consequences for the understanding of landscape evolution, natural hazards, and the safe and sustainable 
operation of high-mountain infrastructure. Permafrost in steep bedrock is an emerging field of research. Knowledge of rock temperatures, ice content, mechanisms of degradation, and the processes that link warming and destabilization is often fragmental. 
In this article we provide a review and discussion of existing literature and pinpoint important questions. Ice-filled joints are common in bedrock permafrost and possibly actively widened by ice segregation. Broad evidence of destabilization by warming permafrost exists despite problems of attributing individual events to this phenomenon 
with certainty. Convex topography such as ridges, spurs, and peaks is often subject to faster and deeper thaw than other areas. Permafrost degradation in steep bedrock can be 
strongly affected by percolating water in fractures. This degradation by advection is difficult to predict and can lead to quick and deepdevelopment of thaw corridors along 
fractures in permafrost and potentially destabilize much greater volumes of rock than conduction would. Although most research on steep bedrock permafrost originates from the Alps, it will likely gain importance in other geographic regions with mountain permafrost.

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Permafrost in steep bedrock slopes and its temperature‐related destabilization following climate change

Interaction of cement model systems with superplasticizers investigated by atomic force microscopy, zeta potential, and adsorption measurements.

Analysis of cement-bonded materials by multi-cycle mercury intrusion and nitrogen sorption.

Experimental studies and thermodynamic modeling of the carbonation of Portland cement, metakaolin and limestone mortars

On the use of peak-force tapping atomic force microscopy for quantification of the local elastic modulus in hardened cement paste

When cement with mineral additions is employed, the carbonation resistance of mortar and concrete may be decreased. In this study, mortars containing mineral additions are exposed both to accelerated carbonation (1% and 4% CO2) and to natural carbonation. Additionally, concrete mixtures produced with different cements, water-to-cement ratios and paste volumes are exposed to natural carbonation. The comparison of the carbonation coefficients determined in the different exposure conditions indicates that mortar and concrete containing slag and microsilica underperform in the accelerated carbonation test compared to field conditions. The carbonation resistance in mortar and concrete is mainly governed by the CO2 buffer capacity per volume of cement paste. It can be expressed by the ratio between water added during production and the amount of reactive CaO present in the binder (w/CaOreactive) resulting in a novel parameter to assess carbonation resistance of mortar and concrete containing mineral additions.

Josef Kaufmann

Papers

Interaction of cement model systems with superplasticizers investigated by atomic force microscopy, zeta potential, and adsorption measurements.

Analysis of cement-bonded materials by multi-cycle mercury intrusion and nitrogen sorption.

Experimental studies and thermodynamic modeling of the carbonation of Portland cement, metakaolin and limestone mortars

On the use of peak-force tapping atomic force microscopy for quantification of the local elastic modulus in hardened cement paste

Relation between carbonation resistance, mix design and exposure of mortar and concrete