Effect of aggregate size and amount on the mechanical properties of engineered cementitious composites incorporating fly ash and slag

Engineered Cementitious Composites (ECC) is a special type of high performance fiber reinforced cementitious composite featuring high ductility and damage tolerance under mechanical loading, including tensile and shear loadings. The relative high cost remains an obstacle for wider commercial use of ECC. The replacement of Portland cement by fly ash and slag, and an increase in the amount and size of aggregate used in ECC production can lower its cost and enhance its greenness of composites, since the production of these materials needs less energy and causes less carbon dioxide emission than cement. The studies reported in this thesis indicate that an experimental program is undertaken to study the dependence of the composite properties on its mixture composition governed by mineral admixture types and amount, and maximum aggregate size and amount. Test results revealed that with proper selection of the type and amount of mineral admixture, aggregates within the amount and size range studied do not negatively influence the ductility of ECC, increase in the age of restrained shrinkage cracking, and a significant decrease in the drying shrinkage capacity. Together with the enhanced composite mechanical properties with the standard ECC mixture produced with micro silica sand and dimensional stability enhancement, the substantial use of these mineral admixtures from industrial processes and the increasing of maximum grain size and amount of sand in the production of ECC is an important step toward sustainability in the construction industry.