Structure and phase investigations on crystallization of 11 Å tobermorite in lime sand pellets

Hartmann, Andrea; Buhl, Josef‐Christian; Breugel, K. van

doi:10.1016/j.cemconres.2006.09.007

Cited by 30 publications

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“…For both types first reference syntheses without additives were prepared. As in former experiments on CSH crystallization [25]- [28] for all syntheses with powders 1.5 g fine grained quartz with particle size > 230 mesh (FLUKA 83340) Table 1. The individual mass ratios were selected to obtain a C/S ratio of 0.8 for the references and the experiments with calcium formate and calcium chloride dihydrate.…”

Section: Synthesesmentioning

confidence: 99%

Investigation of the Transition Reaction of Tobermorite to Xonotlite under Influence of Additives

Hartmann¹,

Schulenberg²,

Buhl³

2015

ACES

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The objective of the present work was to investigate the transition reaction of the calcium silicate hydrate tobermorite into xonotlite under influence of additives. Tobermorite is the main binding agent in steam hardened building materials and the appearance of xonotlite indicates the progress of hardening and an overcuring of the material. Hydrothermal experiments under addition of sucrose, calcium formate and calcium chloride dihydrate to the main components quartz and lime were done using temperatures of 220˚C and a reaction time of 40.5 h. All experiments were performed with powders as well as with pressed educts. The products of all syntheses were analyzed with XRD, SEM/EDX and FTIR. The references as well as the syntheses with calcium chloride dihydrate led to the formation of 11 Å tobermorite and xonotlite. The former showed the best results and even synthesis with pressed educts and calcium chloride dihydrate revealed an accelerating effect of the additive. In contrast syntheses with sucrose had the worst reactivity and led to the formation of calcite beside the CSH-phase scawtite. The additive calcium formate was only slightly oppressing the crystallization of tobermorite and favouring the formation of xonotlite. Syntheses with pressed pellets and sucrose or calcium formate showed generally worse results.

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Section: Synthesesmentioning

confidence: 99%

Investigation of the Transition Reaction of Tobermorite to Xonotlite under Influence of Additives

Hartmann¹,

Schulenberg²,

Buhl³

2015

ACES

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“…18,24,28 Serry et al found that hydrogarnet crystallized at the early stage of hydration in the low-lime content mixtures of metakaolin and lime. 29 Siauciunas and Baltusnikas determined that hydrogarnet always tended to form more rapidly than tobermorite in the CaO-quartz and CaOamorphous SiO 2 …”

Section: 19mentioning

confidence: 99%

Microstructure and characterization of aluminum-incorporated calcium silicate hydrates (C–S–H) under hydrothermal conditions

Zhao

2018

RSC Adv.

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The phase assembly and microstructure of the aluminum-incorporated CaO-SiO 2 -H 2 O system, which is technologically important in autoclaved building materials, catalysis and waste management, were investigated using XRD, SEM, FTIR and NMR depending on aluminum addition, reaction temperature and curing time. The content of each phase was obtained using the MAUD program based on the Rietveld refinement. The results revealed that the formation of the tobermorite phase was promoted at Al/(Al + Si) # 0.03, and subsequently retarded by higher aluminum addition, which was corroborated by the presence of more low polymerized and cross-linked (alumino)silicate chains. The phase purity decreased with increasing aluminum addition. Aluminum changed the morphology of tobermorite from plate-like to lath-like and fibrous. About a quarter of the (alumino)silicate chains in the C-S-H structure were linked though a^Si-O-Al^configuration, and this proportion was almost independent of aluminum addition. Furthermore, only Al[4] substituted for silicon in the aluminum incorporated C-S-H, while Al [6] just exited in the hydrogarnet phase. This work is beneficial for understanding the implication on microproperties of by-products or admixtures containing aluminum in concrete.

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“…In a traditional production of autoclaved silicate products, amorphous C-S-H and crystal tobermorite (C5S6H5) are usually synthesis products [17][18][19][20]. According to the literature data, the strength of autoclaved materials depends on the total content of the two mineral phases [21,22].…”

Section: Resultsmentioning

confidence: 99%

Effects of Bentonite Additives on Autoclaved Sand-Lime Product Properties

Owsiak

Kostrzewa

2017

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. The paper presents the results of the research on modifications of sand-lime bricks with bentonite additives. The article presents correlations between physico-mechanical properties and a microstructure of traditional silicates and products modified with bentonite. Numerous images of scanning electron microscopy included in the article show the internal structure and phases occurring in both traditional and modified sand -lime products. The addition of bentonite results in a reduction of sand-lime products density and their compressive strength. The modified products achieve lower absorbability than conventional silicates by about 50%. The addition of bentonite changes the structure of pores and their distribution. The modified composition of a traditional silicate product contributed to changing the microstructure of the material (hydrogranates are formed).

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Structure and phase investigations on crystallization of 11 Å tobermorite in lime sand pellets

Cited by 30 publications

References 0 publications

Investigation of the Transition Reaction of Tobermorite to Xonotlite under Influence of Additives

Investigation of the Transition Reaction of Tobermorite to Xonotlite under Influence of Additives

Microstructure and characterization of aluminum-incorporated calcium silicate hydrates (C–S–H) under hydrothermal conditions

Effects of Bentonite Additives on Autoclaved Sand-Lime Product Properties

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