Durability of concrete — Degradation phenomena involving detrimental chemical reactions

The Chicxulub crater ejecta stratigraphy is reviewed, in the context of the stratigraphy of underlying and overlying rock sequences. The ejecta sequence is regionally grouped in (a) thick polymict and monomict breccia sequences inside the crater and within 300 km from the rim of the crater known from drill holes in and close to the breater, and exposures near the border of Yucatan and Belize; (b) Gulf of Mexico region, <2500 m from the crater, with up to 9 m thick, complex, tsunami-wave influenced, tektite-bearing sequences in shallow marine (<500 m deep) environments and tektite bearing, decimeter thick gravity-flow deposits in deep water sites; (c) an intermediate region between 2500 and 4000 km from the crater where centimeter thick, tektite-bearing layers occur, and (d ) a global distal region with a millimeter thin ejecta layer. The distal ejecta layer is characterized by sub-millimeter sized microkrystites, often rich in Ni-rich spinels and (altered) clinopyroxene. Wherever present, the ejecta layers mark exactly the sudden mass-mortality horizon of the K/T boundary. What exactly caused the mass mortality is still uncertain, but it appears the main event leading to the K/T mass extinctions.

The global stratigraphy of the cretaceous-tertiary boundary impact ejecta

Bioreceptivity of building stones: a review.

Sedimentary Geology. (Book Reviews: Aspects of Diagenesis. Papers from symposiums, Mar. 1976 and Apr. 1977)

Phase and morphology evolution of CaCO3 precipitated during carbonation of lime pastes via the reaction Ca(OH)2 + CO2 → CaCO3 + H2O has been investigated under different conditions (pCO2 ≈ 10−3.5 atm at 60 % RH and 93 % RH; pCO2 = 1 atm at 93 % RH) using XRD, FTIR, TGA, and SEM. Simulations of the pore solution chemistry for different stages and conditions of carbonation were performed using the PHREEQC code to investigate the evolution of the chemistry of the system. Results indicate initial precipitation of amorphous calcium carbonate (ACC) which in turn transforms into scalenohedral calcite under excess Ca2+ ions. Because of their polar character, $$ \left\{ {21\bar{3}4} \right\} $$
 scalenohedral faces (type S) interact more strongly with excess Ca2+ than non-polar $$ \left\{ {10\bar{1}4} \right\} $$
 rhombohedral faces (type F), an effect that ultimately favors the stabilization of $$ \left\{ {21\bar{3}4} \right\} $$
 faces. Following the full consumption of Ca2+ ions and further dissolution of CO2 leading to a pH drop of the pore solution, $$ \left\{ {21\bar{3}4} \right\} $$
 scalenohedra are subjected to dissolution. This eventually results in re-precipitation of $$ \left\{ {10\bar{1}4} \right\} $$
 rhombohedra at close-to-neutral pH. This crystallization sequence progresses through the carbonated depth with a strong dependence on the degree of exposure to CO2, which is controlled by the carbonated pore structure governing the diffusion of CO2. Both the carbonation process and the scalenohedral-to-rhombohedral transformation are kinetically favored under high RH and high pCO2. Supersaturation plays a critical role on the nucleation density and size of CaCO3 crystals. These results have important implications in understanding the behavior of ancient and modern lime mortars for applications in architectural heritage conservation.

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Phase and morphology evolution of calcium carbonate precipitated by carbonation of hydrated lime

https://www.ugr.es/~grupo179/pdf/Cultrone%2005b.pdf

Forced and natural carbonation of lime-based mortars with and without additives: Mineralogical and textural changes

http://www.ugr.es/~grupo179/pdf/Cultrone%2007.pdf

Durability of masonry systems: A laboratory study

The geochemistry and mineralogy of the Cretaceous-Tertiary boundary at Agost (southeast Spain)☆

Comparative mineralogical and geochemical clay sedimentation in the Betic Cordilleras and Basque-Cantabrian Basin areas at the Cretaceous-Tertiary boundary

M. Ortega Huertas

Papers

Forced and natural carbonation of lime-based mortars with and without additives: Mineralogical and textural changes

Durability of masonry systems: A laboratory study

The geochemistry and mineralogy of the Cretaceous-Tertiary boundary at Agost (southeast Spain)☆

Comparative mineralogical and geochemical clay sedimentation in the Betic Cordilleras and Basque-Cantabrian Basin areas at the Cretaceous-Tertiary boundary

Quench textures in altered spherules from the Cretaceous-Tertiary boundary layer at Agost and Caravaca, SE Spain