Effect of oyster shell substituted for fine aggregate on concrete characteristics: Part I. Fundamental properties

An experimental study was carried out to investigate the recycling possibilities for fine aggregate of oyster shells (OS), which is an industrial waste, disposed of in open dumps at coastal oyster management areas. For this purpose, the chemical components of OS and reactivity of OS with cement paste were examined. More specifically, mechanical characteristics of fresh concrete and hardened concrete were quantitatively investigated in terms of fineness modulus (F.M.) and substitution rate (SR) of crushed OS. In addition, the Part II paper presents the performance of concrete up to 1 year with OS substituted for fine aggregate.Test results show that the interaction between OS and cement paste did not occur and the workability of concrete decreased with F.M. decrease and SR of OS increase. In addition, it was found that mixing of OS did not cause reduction in the compressive strength of concrete at age 28 days and development of compressive strength was faster as SR of OS increased. Elastic modulus of concrete substituted with crushed OS decreases as SR increases. The decrease was approximately 10% at SR of 20%.