The Pozzolanic Activity of Calcined Clay – Silica Gel Composites

The effect of silica gel additive on pozzolanic activity of burned clays was investigated on this study. It was determined that calcined (600[degrees]C-730[degrees]C) clay of Saltiskiai quarry has very low pozzolanic activity (104 mg-55 mg CaO/g). It was observed that during calcination process the fluorine ions from silica gel were not combined to another compounds but directly passed to atmosphere. Moreover, silica gel additive significantly increases the mentioned clay activity, which depends on the quantity of the used additive. It was determined that 10% of silica gel additive increases the pozzolanic activity of composite with clay of Saltiskiai quarry up to 109 mg CaO/g, meanwhile the 80% - unto 257 mg CaO/g. The same effect of silica gel additive was observed in the samples with Dukstyna quarry clay. It was found that the pozzolanic activity of Dukstyna clay-silica gel composite with 10% of silica gel additive, burned at 600 [degrees]C for 1h, was 7% higher (168 mgCaO) than the activity of the clay samples (157 mgCaO/g), whereas 229 mgCaO/g pozzolanic activity was reached than 80% additive of silica gel was used. Despite this fact, the pozzolanic activity decreases when the calcination at 700 [degrees]C - 860 [degrees]C temperature was carried out.Original Abstract: Degtas molis yra viena seniausiai zinomu pucolaniniu medziagu, kudos savybes priklauso nuo molio mineralu sudeties. Atsizvelgiant i jo gebejima reaguoti su Ca(OH) sub(2) ir sudaryti junginius, pasizymincius risamosiomis savybemis, degtas molis gali pakeisti dali cemento ir padidinti gaminiu stipruma ir ilgaamziskuma. Zinoma, kad, didejant pucolaniniam aktyvumui, reakcijos tarp amorfinio SiO sub(2) ir Ca(OH) sub(2) metu susidaro didesni kiekiai antriniu kalcio hidrosilikatu. Kadangi Lietuvos pramoniniu telkiniu moliuose mineralo kaolinito, termines aktyvacijos metu galincio igyti aktyvia amorfine metakaolinito forme, kiekis nera pakankamas geroms pucolaninems savybems pasiekti, todel siu moliu pucolanini aktyvume butu galima pagerinti pridejus silikagelio. Tyrimo metu buvo istirta silikagelio itaka degtu Saltiskiu molio ir silikagelio bei Dukstynos molio ir silikagelio kompozitu pucolaniniam aktyvumui. Siam tikslui buvo paruosti moliu su 10, 20, 50 ir 80% silikagelio priedu misiniai, is kuriu suformuotos granules, 1 h degtos 600 [degrees]C - 860 [degrees]C temperaturose. Nustatyta, kad molio ir silikagelio sistemoje didejant silikagelio priedo kiekiui degtu kompozitu pucolaninis aktyvuma