31 KB301 KB30 KB200020242000Valič, MarkoVuk, Tomažletnik:34številka:57 stranistr. 249-255ISSN:1580-2949COBISSID:782691URN:URN:NBN:SI:doc-V3DVEJ6RslInštitut za kovinske materiale in tehnologijeMateriali in tehnologijeaditivicementhidratacijaultrazvočna preiskava materialaŠtudij vpliva aditivov in dodatkov na hidratacijo cementa s pulzno USWR-metodo| A study of the influence of additives and admixtures on the hydration of cement with the pulsed USWR method|In this contribution the results of a study of the influence of the addition of selective additives and of small admixtures on the early hydration of portland cement with the pulsed-ultrasonic-shear-wave reflection (USWR) method, are presented. With this measurements the information on the growth of the physical strength of the fragile cement gel in the early hydration stage are obtained in a continuous, nondestructive way with no external shear applied. The reatarding/accelerating effects of additives and admixtures on the time development of the shear rigidity are very pronounced as is evident from the results obtained. They also demonstrate the suitability of the method and the preformance of the apparatus used. An attempt to correlate the change in the reflection coefficient of the shear waves due to hydration after one day with the compressive and bending strength and with the amount of the hydrated material using thermogravimetry is also respondV prispevku so prikazani rezultati študija vpliva dodajanja izbranih aditivov in manjših količin standardnih dodatkov za začetno hidratacijo portland cementa, dobljeni s pulzno metodo odboja ultrazvočnih strižnih valov (USWR-metoda). Metoda omogoča pridobitev informacij o rasti fizične trdnosti zelo krhkega cementnega gela v zgodnji fazi hidratacije kontinuirano, neporušno in brez zunanje mehanske strižne obremenitve vzorcev. Prikazani rezultati zelo razvidno kažejo na zavlačevalno/pospeševalne vplive aditivov in vplive dodatkov in na časovni potek rasti trdnosti cementnih plasti in istočasno tudi na primernost metode in na delovanje uporabljenega aparata za karakterizacijo teh materialov. Podani so tudi poskusi korelacije med spremembo odbojnega koeficienta strižnih valov zaradi hidratacije po enem dnevu in tlačno ter upogibno trdnostjo in količino hidratizirane snovi z uporabo termogravimetrijeTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaInštitut za kovinske materiale in tehnologije