The effect of different mineral additions and synthetic fiber contents on properties of cement based composites

The influence of the matrix formulation and different amounts of synthetic fiber on physical and mechanical performance of asbestos free fiber cement was evaluated. Polyvinyl alcohol (PVA) fiber was tested as reinforcement in combination with mechanical and kraft cellulose pulps. Silica-fume, metakaolin and fly ash were used as pozzolanic additions in proportions up to ∼14% by mass in combination with ordinary Portland cement and carbonatic filler. Bulk densities of composites varied from 1.5 to 1.7 g/cm3. Synthetic fiber contents higher than 2% by mass (from 4% to 5% by volume of the composite) were unable to promote any further improvement in the mechanical performance of the composites at the age of 28 days. Formulations with silica fume showed better strength performance for the composites after accelerated aging test. The toughness measurements of composites after exposition to soak and dry cycles also showed that silica fume seems to prevent cellulose fiber degradation.