Abstract
This paper presents a comprehensive review on structural lightweight aggregate concrete (SLWAC) durability. The main transport properties and degradation mechanisms of reinforced concrete are addressed, namely, carbonation and chloride attack. The influence of the main composition parameters, such as type of aggregate, type of binder and water/binder ratio, as well as the influence of cracking, are also analysed. Finally, the current knowledge of SLWAC’s service life prediction is assessed. Although the knowledge of SLWAC’s durability behaviour is still limited, investigation works performed either in laboratory or in real environments indicate that SLWAC can have similar to better durability performance than normal weight concrete, especially when the same strength level is considered. The importance of the quality of the paste over the characteristics of the lightweight aggregates is highlighted. Durability standardization regarding SLWAC is still insufficient and is one of the main gaps of current knowledge. The objective of this review is to foster a better understanding on the durability and service life prediction of SLWAC, contributing to a greater confidence in using this type of concrete.
Highlights
Structural lightweight aggregate concrete (SLWAC) has been used for more than 2000 years, it only assumed greater relevance in construction in the middle of the twentieth century, especially in solutions where the self-weight is a relevant factor, such as in high-rise buildings, shell and slender structures, long-span bridges and rehabilitation works
structural lightweight aggregate concrete (SLWAC) has been the subject of ongoing technologic and scientific developments, especially in the last three decades, after the technological development of high-performance concrete, the research and application of new admixtures, the advances in manufacturing new lightweight aggregates (LWA) and, most of all, due to the more exigent durability requirements in marine structures, where SLWAC may double the percentage of load reduction [1,2]
Real and Bogas [125] found that the incorporation of 15–30% lime filler (LF) in SLWAC led to higher chloride penetration than in SLWAC with OPC, given that the contribution of this type of mineral admixture to microstructural refinement through the filler and nucleation effects was not offset by the reduction of cement hydration products and of its non-chloride binding capacity
Summary
Structural lightweight aggregate concrete (SLWAC) has been used for more than 2000 years, it only assumed greater relevance in construction in the middle of the twentieth century, especially in solutions where the self-weight is a relevant factor, such as in high-rise buildings, shell and slender structures, long-span bridges and rehabilitation works. Research carried out in this domain shows that the durability and service life performance of SLWAC are influenced by various factors, such as the type of LWA, concrete composition, exposure and testing. Thienel et al [15] reported good durability against freezing and thawing, carbonation and chloride attack of different types of SLWAC from 15 structures in Germany. Both studies indicate that an eventual poor durability of SLWAC may be related to its production process and greater tendency for aggregate segregation. This paper discusses most relevant advances in the durability of SLWAC subjected to two of the most frequent and serious concrete deterioration mechanisms; carbonation and chloride induced corrosion. The objective of this review is to foster a better understanding of the durability and service life prediction of SLWAC and highlight some of the future research needs in this domain
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