@article{fdi:010048301,
  title = {{E}ffects of the secondary minerals of the natural pozzolans on their pozzolanic activity},
  author = {{H}abert, {G}. and {C}houpay, {N}. and {M}ontel, {J}ean-{M}arc and {G}uillaume, {D}. and {E}scadeillas, {G}.},
  editor = {},
  language = {{ENG}},
  abstract = {{N}atural pozzolans have been widely used as substitutes for {P}ortland cement, because of their binding properties. {S}ome of them are natural volcanic rocks which contain secondary minerals such as clays and zeolites corresponding to products of the alteration of the rock. {T}he objective of this study was to document the potential effect of the secondary minerals on the strength development of pozzolanic mortars. {W}e chose to investigate this effect by thermally destabilising these minerals in three different pozzolanic deposits (poz-1, poz-2 and poz-3). {W}e first did a detailed mineralogical study, to identify the occurrence and the nature of the different secondary minerals. {K}aolinite is abundant in poz-1 and different types of zeolite were identified in poz-2 and poz-3. {T}hermal treatments were monitored by {X}-ray {D}iffraction ({XRD}) analysis, in order to document mineralogical transformations. {T}he effect on the pozzolanic activity has been tested by strength measurements on normalised mortars at 1, 7 and 28 days. {S}trength of all blended cements is enhanced while destabilising secondary alteration minerals. {F}or kaolinite, we showed that a strength improvement occurs as soon as it is destructured, even if it is not transformed in metakaolin. {F}or zeolites, destabilisation takes place at low temperature (350 degrees {C}), but as recrystallisation products are easily formed, activation temperature window is narrow. {E}ndly, we have evidence that the presence of calcite in pozzolans has an effect on early strength. {T}herefore this study is giving new perspectives for a better use of natural pozzolanic materials in the cement industry.},
  keywords = {thermal treatment ; {SEM} ; {X}-ray diffraction ; compressive strength ; pozzolan},
  booktitle = {},
  journal = {{C}ement and {C}oncrete {R}esearch},
  volume = {38},
  numero = {7},
  pages = {963--975},
  ISSN = {0008-8846},
  year = {2008},
  DOI = {10.1016/j.cemconres.2008.02.005},
  URL = {https://www.documentation.ird.fr/hor/fdi:010048301},
}