Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 Materials Science Poland

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: tobermorit

Sortuj według:

Ogranicz wyniki do:

The influence of gamma-Al2O3 and Na2O on the formation of calcium silicate hydrates in the CaO-quartz-H2O system

Baltakys K., Siauciunas R.

Materials Science Poland

2007

Vol. 25, No. 1

185--198

The influence of gamma-Al2O3 and Na2O additives on the formation and sequence of calcium silicate hydrates in the CaO-quartz-H2O system with CaO/SiO2 (C/S) molar ratio equal to 0.66 was determined. The synthesis was carried out in unstirred suspensions. The molar ratios of the primary mixtures were CaO/(SiO2 + Al2O3) = 0.66 and Al2O3/(SiO 2 + Al2O3) = 0 or 0.025. The amount of NaOH, corresponding to 5% of Na2O in the mass of dry material, was added in the form of solution. Due to the low solubility rate of quartz in the CaO-quartz-H2O system with C/S = 0.66 in the temperature range 150-200°C, low-base calcium silicate hydrates (Z-phase, gyrolite, pectolite, and others) do not form even after 72 hours of hydrothermal curing. It has been proved that gamma-Al2O3 and Na2O additives change the reaction mechanisms and composition of intermediate (final) products. In mixtures with Na2O, gyrolite starts to form already at 175°C. It should be noted that in the temperature range 175-200°C the final products are gyrolite and pectolite, and the intermediate compounds are C-S-H(l) and Z-phase. The formation of low-base calcium silicate hydrates in the CaO-quartz-Na2O-H2O system is slowed down when Al 2O3 is added because Al3+ ions stimulate the formation of tobermorite and prevent the formation of pectolite and Z-phas

Influence of tribomechanical milling and activation of primary mixtures on the synthesis of calcium silicate hydrates

Palubinskaite D., Kantautas A.

Materials Science Poland

2006

Vol. 24, No. 2/1

395--403

Tobermorite group minerals with double [Al3++Na+] substitution, using non grind row minerals mixture and grind mixtures in the colloidal mill were syntheses. Calcium silicate hydrate synthesis is going on more intense, when dry primary mixtures ground in a colloid mill are taken, because, having the same synthesis conditions, the compositions of higher crystal degree are synthesized. In this case after 24 h tobermorite forms itself. It is thought, that grinding in a colloid mill a mixture of CaO; SiO2 and Al2O3 some activation centres are induced, which later in the process of hydrothermal processing activate the process of synthesis run. It is reasonable to grind in colloid mill the dry component mixtures, used for synthesis of tobermorite, before hydrothermal processing, until optimum. In the research conditions given the tobermorite formed more intense when original surface was less: S = 547 m2/kg. It is not expedient to use mixtures of smaller primary materials, because stabilizing influence of C-S-H(I) on over forming kinesis of tobermorite displayed itself.