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has been cited by the following article:

• TITLE: Pozzolanic Activity of Old Volcanic Tuffs of Mako Area (Senegal-Oriental, West African Craton): An Economic and Environmental Interest

  AUTHORS: Matar Ndiaye, Mahamadane Diène, Mouhamadou Bassir Diop, Papa Malick Ngom

  KEYWORDS: Old, Volcanic, Tuffs, Calc-Alkaline, X-Ray Diffractions, Amorphous, Pozzolanic, Cements, Compressive Strength, Economic, Environmental

  JOURNAL NAME: International Journal of Geosciences, Vol.10 No.3, March 15, 2019

  ABSTRACT: The volcanic tuffs of Senegal-Oriental in Mako area are produced during a calc-alkaline volcanism which occurs in this region and which is dated from about 2.3 - 1.95 Ga. Despite their altered appearance, the X-Ray diffractions show mineral paragenesis: Quartz-Kaolinite-Illite and an important amorphous phase. On the Ternary Keil-Rankin diagram for the CaO-SiO2-Al2O3 the volcanic tuffs of Mako area are situated between pozzolan and the fly ash. The difference between silica and lime is greater than 34% in these volcanic tuffs. In this study, they have been mixed with Portland cement to obtain pozzolanic cements respectively with 20%, 30%, 35% and 40% of addition of volcanic tuffs. The pozzolanic reactivity is highlighted by the compressive strength increase until 90 days of conservation in water. It supposes that the vitreous phase of the volcanic tuffs reacts with the free CaO (CaOf) of Portland cement to produce new hydrated minerals. This study has a positive economic and environmental impact. Because the time of grinding of pozzolanic cements is reduced. Also, the addition of volcanic tuffs reduces the production of clinker, then the CO2 emission.