The stability of tobermorite in the system CaO-SiO<sub>2</sub>-H<sub>2</sub>O at elevated temperatures and pressures

Speakman, K.

doi:10.1180/minmag.1968.036.284.06

Cited by 26 publications

(13 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This leads to cleavages (cracks of parallel orientation fixed by the initial atomic network). The fibres of the resulting xonotlite occurred in parallel laths in the form of a bundle (observations by HFW Taylor in the 1960s) (Speakman, 1968). The addition of 40% slag in lime substitution did not disturb the fundamental aspect of these two phases (Figures 10(a) and 10(b)).…”

Section: Microstructural Analysesmentioning

confidence: 97%

Formation of C-S-H in calcium hydroxide–blast furnace slag–quartz–water system in autoclaving conditions

Arabi

Jauberthie

Chelghoum

et al. 2015

Advances in Cement Research

View full text Add to dashboard Cite

In masonry, the most commonly used materials are concrete blocks or burnt clay brick. Owing to energy costs, there is a need to explore alternative raw materials and energy-efficient technologies for making building materials. This paper deals with the incorporation of blast furnace granulated slag in sand-lime materials as a replacement for hydrated lime during autoclaving conditions. The slag grain-size grinding and the heat treatment in saturated vapour pressure autoclave conditions were investigated to study the compressive strength behaviour of the new material.This substitution induces a decrease in compressive strength. The reaction products consist mainly of 11 nm tobermorite and xonotlite. The X-ray diffractions of these phases are difficult to see. The slag seems more reactive with lime than quartz. Observations with the scanning electron microscope allow better appreciation of these crystallites. With its composition and amorphous structure, the granulated slag does not release new distinct phases of hydrates.

show abstract

Section: Microstructural Analysesmentioning

confidence: 97%

Formation of C-S-H in calcium hydroxide–blast furnace slag–quartz–water system in autoclaving conditions

Arabi

Jauberthie

Chelghoum

et al. 2015

Advances in Cement Research

View full text Add to dashboard Cite

show abstract

“…Microprobe analyses gave totals of 90 wt.% and show minor substitutions of Al and Na for Si and Ca (Table 7). Experimental data show that gyro-lite, a calcium silicate hydrate, is only stable at 140 to 220°C (Speakman, 1968). It is a common late vein and vesicle-filling phase in the laumontite-prehnite-quartzchlorite metamorphic zone in the Deccan Traps, where it also predates apophyllite (Sukheswala et al, 1974).…”

Section: Apophyllite and Gyrolitementioning

confidence: 99%

Primary Composition, Alteration, and Origin of Cretaceous Volcaniclastic Rocks, East Mariana Basin (Site 585, Leg 89)

Viereck¹,

Simon²,

Schminke³

1986

Initial Reports of the Deep Sea Drilling Project

View full text Add to dashboard Cite

An upper Aptian to middle Albian series of volcaniclastic rocks more than 300 m thick was drilled at Site 585 in the East Mariana Basin. On the basis of textural and compositional (bulk-rock chemistry, primary and secondary mineral phases) evidence, the volcaniclastic unit is subdivided into a lower (below 830 m sub-bottom) and an upper (about 670-760 m) sequence; the boundary in the interval between is uncertain owing to lack of samples.The rocks are dominantly former vitric basaltic tuffs and minor lapillistones with lesser amounts of crystals and basaltic lithic clasts. They are mixed with shallow-water carbonate debris (ooids, skeletal debris), and were transported by mass flows to their site of deposition.The lower sequence is mostly Plagioclase-and olivine-phyric with lesser amounts of Ti-poor clinopyroxene. Mineralogical and bulk-rock chemical data indicate a tholeiitic composition slightly more enriched than N-MORB (normal mid-ocean ridge basalt). Transport was by debris flows from shallow-water sites, as indicated by admixed ooids. Volcanogenic particles are chiefly moderately vesicular to nonvesicular blocky shards (former sideromelane) and less angular tachylite with quench Plagioclase and pyroxene, indicating generation of volcanic clasts predominantly by spalling and breakage of submarine pillow and/or sheet-flow lavas.The upper sequence is mainly clinopyroxene-and olivine-phyric with minor Plagioclase. The more Ti-rich clinopyroxene and the bulk-rock analyses show that the moderately alkali basaltic composition throughout is more mafic than the basal tholeiitic sequence. Transport was by turbidity currents. Rounded epiclasts of crystalline basalts are more common than in the lower sequence, and, together with the occurrence of oxidized olivine pseudomorphs and vesicular tachylite, are taken as evidence of derivation from eroded subaerially exposed volcanics. Former sideromelane shards are more vesicular than in the lower sequence; vesicularity exceeds 60 vol.% in some clasts. The dominant clastic process is interpreted to be by shallow-water explosive eruptions.All rocks have undergone low-temperature alteration; the dominant secondary phases are "palagonite," chlorite/ smectite mixed minerals, analcite, and chabazite. Smectite, chlorite, and natrolite occur in minor amounts. Phillipsite is recognized as an early alteration product, now replaced by other zeolites. During alteration, the rocks have lost up to 50% of their Ca, compared with a fresh shard and fresh glass inclusions in primary minerals, but have gained much less K, Rb, and Ba than expected, indicating rapid deposition prior to significant seafloor weathering.

show abstract

“…Once the CO 2 pressure equilibrated, the pump was switched to nitrogen gas and the pressure was increased to 15.5 MPa. Each experiment was conducted for 24 h, and afterward, the samples, in the Teflon boats, were oven-dried at 75 °C where sheet silicate precipitates are not expected to form. , Upon drying, the sand and powders became separable, and the powders were then rinsed three times to remove any remaining NaOH and dried at 50 °C for 12 h. The products of select samples were then divided, and a portion was acid-washed in a pH 5.5 acetic acid/sodium acetate-buffered solution for 6 h . To remove the acid, those samples were again rinsed and oven-dried.…”

Section: Materials and Methodsmentioning

confidence: 99%

Calcium Silicate Crystal Structure Impacts Reactivity with CO₂ and Precipitate Chemistry

Plattenberger

Ling

Tao

et al. 2018

Environ. Sci. Technol. Lett.

View full text Add to dashboard Cite

The reaction of CO 2(aq) with calcium silicates creates precipitates that can impact fluid flow in subsurface applications such as geologic CO 2 storage and geothermal energy. These reactions nominally produce calcium carbonate (CaCO 3 ) and amorphous silica (SiO x ). Here we report evidence that the crystal structure of the parent silicate determines the way in which it reacts with CO 2 and the resulting structures of the reaction products. Batch experiments were performed using two polymorphs of a model calcium silicate (CaSiO 3 ), wollastonite (chain-structured) and pseudowollastonite (ring-structured), at elevated temperatures (150 °C) and partial pressures of CO 2 (0−11 MPa). Reaction of CO 2(aq) with wollastonite produced CaCO 3 and SiO x , whereas reaction of CO 2(aq) with pseudowollastonite produced platelike crystalline calcium silicate phases, along with CaCO 3 and SiO x . A reaction mechanism that explains the observations in relation to dissolution of the parent silicate, the pH of the solution, and the presence of nucleation sites is proposed. The mechanism is supported with inductively coupled plasma optical emission spectrometry measurements and scanning electron microscopy/transmission electron microscopy−selected-area electron diffraction characterization of solid products. These findings are important for a number of reasons, among them, the fact that the crystalline silicate precipitates are more stable than CaCO 3 under low-pH conditions, which could be valuable for creating permanent seals in subsurface applications.

show abstract

The stability of tobermorite in the system CaO-SiO₂-H₂O at elevated temperatures and pressures

Cited by 26 publications

References 12 publications

Formation of C-S-H in calcium hydroxide–blast furnace slag–quartz–water system in autoclaving conditions

Formation of C-S-H in calcium hydroxide–blast furnace slag–quartz–water system in autoclaving conditions

Primary Composition, Alteration, and Origin of Cretaceous Volcaniclastic Rocks, East Mariana Basin (Site 585, Leg 89)

Calcium Silicate Crystal Structure Impacts Reactivity with CO₂ and Precipitate Chemistry

Contact Info

Product

Resources

About

The stability of tobermorite in the system CaO-SiO2-H2O at elevated temperatures and pressures

Cited by 26 publications

References 12 publications

Formation of C-S-H in calcium hydroxide–blast furnace slag–quartz–water system in autoclaving conditions

Formation of C-S-H in calcium hydroxide–blast furnace slag–quartz–water system in autoclaving conditions

Primary Composition, Alteration, and Origin of Cretaceous Volcaniclastic Rocks, East Mariana Basin (Site 585, Leg 89)

Calcium Silicate Crystal Structure Impacts Reactivity with CO2 and Precipitate Chemistry

Contact Info

Product

Resources

About

The stability of tobermorite in the system CaO-SiO₂-H₂O at elevated temperatures and pressures

Calcium Silicate Crystal Structure Impacts Reactivity with CO₂ and Precipitate Chemistry