Abstract
Dicalcium silicate is one of the main mineral phases of steel slag. Ascribed to the characteristics of hydration and carbonation, the application of slag in cement production and carbon dioxide sequestration has been confirmed as feasible. In the current study, the precipitation process of the dicalcium silicate phase in steel slag was discussed. Meanwhile, the study put emphasis on the influence of different crystal forms of dicalcium silicate on the hydration activity and carbonation characteristics of steel slag. It indicates that most of the dicalcium silicate phase in steel slag is the γ phase with the weakest hydration activity. The hydration activity of γ-C2S is improved to a certain extent by means of mechanical, high temperature, and chemical activation. However, the carbonation activity of γ-C2S is about two times higher than that of β-C2S. Direct and indirect carbonation can effectively capture carbon dioxide. This paper also summarizes the research status of the application of steel slag in cement production and carbon dioxide sequestration. Further development of the potential of dicalcium silicate hydration activity and simplifying the carbonation process are important focuses for the future.
Highlights
According to the statistics of the World Steel Association, the global crude steel output reached 1.864 billion tons in 2020, and the proportion of China’s crude steel output increased from 53.3% in 2019 to 56.5%, reaching 1.053 billion tons [1]
Due to the hydration activity of the dicalcium silicate phase, steel slag is added in a small amount in cement application without affecting the final performance of cement
Carbon dioxide sequestration by steel slag used in Portland cement was presented
Summary
According to the statistics of the World Steel Association, the global crude steel output reached 1.864 billion tons in 2020, and the proportion of China’s crude steel output increased from 53.3% in 2019 to 56.5%, reaching 1.053 billion tons [1]. As an energy-carrying resource, the treatment and comprehensive utilization of steel slag can effectively solve the problems of excessive land occupation, consumption of primary resources, and carbon emissions [5]. No matter the classification standard is, the type, or basicity, the mineral composition of steel slag contains a certain amount of dicalcium silicate phase. No matter the classification standard is, the type, or b2aosfi1c6ity, the mineral composition of steel slag contains a certain amount of dicalcium silicate phase. CCrryyssttaall SSttrruuccttuurree aanndd AAccttiivviittyy ooff DDiiccaallcciiuumm SSiilliiccaattee DDiiccaallcciiuumm ssiilliiccaattee ((CCaa22SSiiOO44,,CC22SS))hhaassaannisislalannddssiilliiccaatteessttrruuccttuurree,,aannddtthheeccrryyssttaallssttrruucc--. ΑTh. eThreelarteiloantisohnipshbipetwbeetewnetehne tehveoleuvtoioluntoiofnCo2Sf cCr2ySstcarlyfsotarlmfoarnmdatnhde tchheacnhgaenogfe toefmtepmerpaetruarteuries isshsohwown nininFiFgiugurere11[1[199].].TThheeeesssseennccee ooff iittss ccrryyssttaall ttrraannssffoorrmmaattiioonn iiss tthhee mmiiggrraattiioonn ooff CCaa aattoommss iinn tthhee ccrryyssttaall ssttrruuccttuurree aanndd tthhee rroottaattiioonn of [SiOO44]]tteettrraahheeddrroonn[2[200,2,211].].TTheheαα’H’−HC−2SCc2hSacnhgaensgreaspridaplyidtolyαt−oCα2S−wC2hSenwhheeantehdeatote1d42to5 1°C42, 5a◦nCd, aαn−dC2αS−cCh2aSngchesantgoesαt’Ho−αC’2HS−wCh2eSnwchoeonlecdootloed1t4o214°2C1.◦βC−.Cβ2−S Cc2hSanchgaensgreaspriadplyidtlyo αto’Lα−C’L2−S Cat2S67a5t 6°C75, a◦Cnd, aαn’d−Cα2’S−cCh2aSncgheasntogeβs−tCo2βS−atC627S0a°tC6.7T0h◦eCr.eTfohreer,etfhoeret,rathnesittriaonsfirtioomn αfr−oCm2Sαt−o Cα2’HS−tCo2αS ’aHn−dCth2Se atrnadnstihteiotnrafnrosimtioαn’Lf−rCom2S αto’Lβ−−C22SS atoreβa−ccCo2mSpaarne iaecdcobmy phaynstierdesbiys [h2y2s,2te3r]e.sis [22,23]. CC22SSppoolylymmoorprphhstsrturcutcutruerseasloanlognwgitwhithetehxeperxipmeernimtaelnotradleorirndgerainndgteamndpetreamtupreersaotuf rpehsasoef ptrhaansseittiroannss[i1ti9o]n, sad[1a9p]t,eaddfarpotmed[1fr9o],mw[i1th9]p, werimthispseiornmfirsosimonAfCroSm, 2A02C1S. , 2021
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