Durabilidade e módulo de elasticidade de misturas areia - cal - cinza volante

Abstract

Study of durability, elastic modulus, split tensile strength and unconfined axial compression strength of a sandy soil stabilized with lime and fly ash, and also, with the cement addition and replacing part of sand with crushed stone. The selected soil was a coastal dune sand, cohesionless and with uniform gradation, in order to enhance the cementitious pozzolanic action of lime plus fly ash when mixed with water. Three mixtures with different proportions wers studied. The first mix had 83% dune sand, 13% fly ash and 4% lime. The second mixture had the same contents of lime, fly ash and dune sand, but having 1% of high initial strength portland cement as additive. The third mixture had 53% dune sand, 30% crushed stone, 4% lime,13% fly ash and 1% of high initial strength portland cement as additive. All mixes were studied at optimum moisture content only. Specimens were molded in cylinders 10 cm diameter and 20 cm height split longitudinally into three parts. Curing ages adopted were: 7, 14, 22, 28, 30, 38 and 90 days. Tests performed were the following: unconfined compressive strength, split tensile strength, durability according to ABCP ("Associação Brasileira de Cimento Portland") method, Iowa method, and the Author's method, and elastic moduli determinations by static and dynamic methods. Unconfined compressive strength reached values up to 137 kgf/cm2 and tensile strength obtained through diametrical compression (split tensile strength) 22 kgf/cm2. Static elastic modulus attained values up to 150,000 kgf/cm2 and the dynamic modulus 178,000 kgf/cm2. Durability testing have shown that adding cement and replacing sand by crushed stone together with the addition of cement improved the quality of mixtures studied. Laboratory research have shown that the mixes studied present good enough characteristics so that they could be aplied in the construction of base and sub-base courses of pavements. However special provisions, probably, should be considered during construction.