• Ferreira, Rui Miguel
• Malheiro, Raphaele
• Costa, Pedro
• Castro-Gomes, João

Abstract

Extensive research and practical experience have shownthat partial replacement of cement by metakaolin improvesconcrete durability as a result of the refinement of thepore structure. While literature confirms much researchon the performance of concrete with metakaolin, it isscarce concerning the performance with regards tochloride penetration, and the effect on the service lifeof reinforced concrete structures.In this study, several concrete mixes were cast withvarying cement type and content and were evaluated fortheir chloride penetration performance. Reference mixeswhere made with CEM I 42,5R and CEM IV/A 42,5 typecements. Two cement contents levels where defined: 330kg/m3 and 440 kg/m3 based on mix designs currently usedin the ready-mix industry for C20/25 and C30/37concretes. Cement was replaced with metakaolin withlevels varying from 10 - 20%. All concretes where testedfor fresh properties, compressive strength, electricalresistivity and chloride diffusion characteristics(migration and ponding), and mercury intrusionporosimetry.The results demonstrate the improved resistance tochloride penetration of concretes with metakaolinadditions. A beneficial effect on strength and durabilityproperties of metakaolin was also observed. In addition,service life design calculations of reinforced concretestructures in marine environment based on the performanceindicators obtained show a significant increase in thetime to fulfil the serviceability limit state ofcorrosion initiation

Topics

• strength
• cement
• durability
• Mercury