Effect of the use of volcanic pozzolan from Mbepit Massif (West-Cameroon) on the mechanical properties of mortar and composite cements production

Abstract

The rise in industrialization and infrastructural development is increasing leading to a constant need for construction materials; however, some of these materials continue to pose a problem to the concerned environments. There is a need to search for materials that will reduce environmental degradation and ensure sustainability. Natural pozzolanic materials possess certain characteristics such that their use in mortar and cement production could reduce the emission of carbon dioxide (CO2) due to the transformation of limestone (CaCO3) into lime for production of Portland cements. Colossal deposits of volcanic pozzolan outcrop in the Njimbouot II locality and the characterization of those materials is vital in deciphering their suitability in cement production as a construction material for sustainable development. Grinding is the only treatment performed on pozzolans in order to increase their specific surface area and reactivity. The rate of substitution of cement with pozzolan in the samples varied from 0%, 10%, and 15% to 25%. Mechanical tests were carried out after 7, 28 and 90 days on mortar specimens (4 × 4 × 16 cm3). Results revealed the presence of amorphous phases. The activity index obtained was approximately 75% and the lapilli and volcanic ash in this area are classified as pozzolans (classification ASTM C618). Regardless of the rate of substitution, the mechanical proprieties of mortars are observed to increase with age. The compressive strength values changed from 33.72 to 52.5 MPa while the flexural strength evolved from 5.62 to 8.29 MPa revealing that the Njimbouot II Pozzolan are advantageous in the manufacture of ecological cements.