Thermal stability and pozzolanic activity of raw and calcined mixed-layer mica/smectite

Microstructure engineering of Portland cement pastes and mortars through addition of ultrafine layer silicates

“…Moreover, it has been shown that replacement of 20 wt.% of the Portland cement by a kaolinite or illitic clay results in an increased porosity of paste samples, but a decreased porosity of mortars as measured by mercury intrusion porosimetry [18]. A decrease in compressive strength of mortars following addition of illite, smectite, kaolinite or illite-smectite was observed by He et al [19,20]. The partly contradictive data from the above mentioned investigations may to some extent reflect varying degrees of dispersion of the clay materials in the cement mixtures.…”

Pozzolanic reactivity of a calcined interstratified illite/smectite (70/30) clay

“…Moreover, while the physical and chemical properties of metakaolin in mortars and concrete have been the subject for a large number of studies [11,12] (and references therein), the potential of interstratified 2:1 clays has not been fully explored. Several studies have examined illite [13], smectite [14][15][16], and a set of clays including mixtures of these 2:1 clays [9,10,[17][18][19][20] but only a handful of studies have focused specifically on 'interstratified' illite/smectite clays [21][22][23].…”

Thermally treated clay sediments as geopolymer source material

“…In fact the thermal activation of clay minerals in the temperature range between 500 and 800°C results generally in a dehydroxylation (Heller-Kallai, 2006), which causes the octahedral sheets lose water and decompose into a disordered metastable state (Evans and White, 1959;Mendelovici, 1997). This meta-state is widely addressed as being reactive as pozzolana (Ambroise et al, 1985(Ambroise et al, , 1987Applied Clay Science xxx (2015) xxx-xxx He et al, 1995aHe et al, , 1995bHe et al, , 2000Baronio and Binda, 1997;Liebig and Althaus, 1997;Kakali et al, 2001;Sabir et al, 2001). Nevertheless, firing to higher temperatures results in the formation of new unreactive phases such as spinel and mullite (Mendelovici, 1997;Bondar et al, 2011a).…”