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Time-lapse drilling of cored boreholes in 1979 and 2017 at Surtsey volcano, Iceland, provides a uniquely informative record of the material and mechanical heterogeneities that develop through interdependent processes of consolidation in very young, oceanic basalt. Integration of laboratory physical property measurements with chemical, mineralogical and microstructural analyses in core segments from subaerial, submarine and subseafloor lapilli tuff deposits, a basaltic intrusion and a xenolithic block of seafloor sedimentary rock reveal heterogeneous physical characteristics within 1963–1967 Surtur crater deposits. The mass of authigenic crystalline cements (zeolites, calcium-silicate-hydrates, sulfites, carbonates) and clay mineral(s) appears similar within the suite of lapilli tuff sub-cores. Connected porosity varies from 42% in weakly-consolidated tuff in a submarine inflow zone to 21% in strongly-lithified tuff in upper subseafloor deposits near the explosively-excavated Surtur conduit. Permeability varies over six orders of magnitude, 4.45 x 10−19– 5.03 x 10−12 m2. Uniaxial compressive strength, P-wave velocity and thermal conductivity are also highly variable: 10–70 MPa, 1.48–4.31 km·s−1 and 0.472–0.862 W·m−1·K−1, respectively. Permeability, micromechanical, and thermal property modeling highlight how porosity and pore-size in eruptive fabrics – modified through diverse cementing microstructures – determine the physical and mechanical properties of the lapilli tuff deposits. The analytical results provide reference parameters for geophysical and heat transfer studies, studies of volcano stability, predictions of rates of change in the physical characteristics of pyroclastic deposits as they lithify at the decadal scale, processes controlling where and when magma erupts, and the mechanical complexities of submarine and subseafloor deposits in Surtseyan volcanoes.

The dark grey bedded limestone from the Ouplaas Mine in Daniëlskuil, South Africa, is currently used to feed both the new 560 tpd Twin Shaft Regenerative (TSR) kilns, recently installed at the local manufacturing lime plant by Cimprogetti Spa. In order to support the client for setting up the quality control of the lime, compositional and microstructural analyses of the limestone, coupled with the technological characterization of limes burnt in laboratory at different temperatures, have been performed (Vola & Sarandrea, 2014). Especially, samples from two different quarry benches (A & B) have been studied to evaluate their burning attitude, and quicklime reactivity. This limestone belongs to the Kogelbeen Fm. of the Campbellrand-Malmani Carbonate Platform, Transvaal Supergroup, which is approximately 2500 Myrs old. It presents characteristic microbial stromatolite laminations, composed of prevalent planar, small scale domal, multi-layered sheets of problematic microorganisms, mainly microbes, originally deposited in a marine shallow subtidal environment. The most of the microfacies are strongly recrystallized. Micro and speudosparites, with ghosts of peloids and mud intraclasts, are dominant with also abundant late diagenetic poikilotopic calcite cement, generally associated with burial diagenesis, mechanical compaction, and pressure solution that produced swarms of thick black stylolites rich of pyrite and graphite (kerogen). The quantitative phase analysis (XRD-QPA) permitted to identify the impurity content, which is mainly ascribed to clay minerals, i.e. illite and chlorite, microcrystalline quartz (chert), and, locally, fabric dolomite. This limestone generally shows a sensitive burning attitude, and an overburning tendency at high temperature, so that the average slaking reactivity (EN 459-2) on limes burnt at 1050°C is very high (t60= 1.3 min. and Tmax= 72°C), but rapidly decreases at 1150°C (t60= 7.5 min. and Tmax= 68°C). Just two different layers of the quarry present significant exceptions, and one of them maintains an high reactivity also at 1150°C (t60= 2.3 min. Tmax= 67°C). The colour of the lime is mainly brown, due to the high content of manganese within the parental limestone. Light brown colour corresponds to soft-burnt limes, dark brown colour to medium-burnt limes, and dark-grey or black colours to hard-burnt limes. This information has been useful to control and setting up important kiln parameters, such as the heat distribution and the burning temperature of the plant. Considering the stratigraphic quarry log, and the reactivity of each layer, it was possible to calculate the average reactivity of each bench, and, subsequently, the expected reactivity of different mixtures feeding the kiln. The following scenarios have been reported: 1) A (100%): t60= 6.5 min.; 2) A (50%) + B(50%): t60= 7.3 min.; 3) B (100%): t60= 8.3 min. This study confirms that specific characteristics of the limestone, such as texture, degree of cementation, presence of dolomite, opaques, and clayey impurities, can significantly impact on quicklime reactivity, as well as, thermodynamic conditions of the process. Moreover, stratigraphic data, associated with laboratory tests, can be successfully adopted to select the best raw mix, reducing the impact of materials of a lesser quality.

This study deals with the characterization of ancient seawater concretes from the Roman harbour of Soli-Pompeiopolis, 1 st century B.C., at Mersin in Turkey, drilled by the ROMACONS (Roman Maritime Concrete Study) team in 2009. This research activity was performed in collaboration with the Laboratories Department of CTG Italcementi Group and the Earth Sciences Department of the University "Federico II" of Naples. Results confirmed that the Roman engineers extensively used coarse tuff aggregate, lime hydrated in seawater, and pozzolanic volcanic fine sand, the so-called pulvis puteolanus of Vitruvius's treatise De Architectura (1 st century B.C.). The typical mineralogical association of phillipsite > chabazite > analcime, in particular points out the provenance for the tuff aggregate from the Yellow Neapolitan Tuff (NYT) formation, which is connected to the Campi Flegrei volcanic activity, dated back to 15.000 years ago. As far as the fine pozzolanic sand, of which just some scoria relics have been observed, can be ascribed to the same formation, or, probably, to the pozzolan stricto sensu pyroclastic flow from the Campi Flegrei area, as well. EDS microanalyses of different phillipsite crystals showed that the content of major alkaline and alkaline-earth metals was very close to those of phillipsite crystals from NYT, with K higher than Na and Ca, as previously reported in the literature. This fact clearly attests that zeolites were not involved in cation exchange processes within the seawater, despite of their long time curing - approximately two thousand years - in the marine environment.

The overburning test method was developed to simulate and predict lime densification, agglomeration, and sporadic melting at the highest potential temperature of lime kilns. These events, that belong to the so-called “sticking tendency” phenomenon, are associated to formation of crusts, occlusions, and blockages in vertical lime kilns. In this work, fifty carbonate rocks, their insoluble residues, and derived burnt products were investigated through a multianalytical approach. Four groups of rocks having different burnability were identified. In addition, three fundamental mechanisms were related to the above-mentioned phenomena: dehydration melting, solid-state, and liquid-phase sintering processes. Guidelines for raw materials suitability were outlined for designing new kilns and to check the quality control in already active plants.

This study evaluates the influence of chemical, mineralogical and petrographic features of the Neoarchean limestone from the Ouplaas Mine (Griqualand West, South Africa) on its burnability and quicklime reactivity, considering the main use as raw material for high-grade lime production in twin shaft regenerative (TSR) kilns. This limestone consists of laminated clotted peloidal micrite and fenestrate microbial boundstone with herringbone calcite and organic carbon (kerogen) within stylolites. Diagenetic modifications include hypidiotopic dolomite, micrite to microsparite recrystallization, stylolites, poikilotopic calcite, chert and saddle dolomite replacements. Burning and technical tests widely attest that the Neoarchean limestone is sensitive to high temperature, showing an unusual and drastically pronounced sintering or overburning tendency. The slaking reactivity, according to EN 459-2 is high for lime burnt at 1050 °C, but rapidly decreases for lime burnt at 1150 °C. The predominant micritic microbial textures, coupled with the organic carbon, are key-factors influencing the low burnability and the high sintering tendency. The presence of burial cementation, especially poikilotopic calcite, seems to promote higher burnability, either in terms of starting calcination temperature, or in terms of higher carbonate dissociation rate. In fact, the highest calcination velocity determined by thermal analysis is consistent with the highest slaking reactivity of the lower stratum of the quarry, enriched in poikilotopic calcite. Secondly, locally concentered dolomitic marly limestones, and sporadic back shales negatively affects the quicklime reactivity, as well. This study confirms that a multidisciplinary analytical approach is essential for selecting the best raw mix for achieving the highest lime reactivity in TSR kilns.