Importance of pumice amount in the design of self-compacting lightweight concrete


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Karadağ E. M., Gürocak M., Kına C., Türk K.

Journal of Structural Engineering & Applied Mechanics (Online), vol.7, no.3, pp.198-218, 2024 (Peer-Reviewed Journal)

Abstract

Although concrete has high compressive strength values, it has a heavy unit volume

and low tensile strength. In this study, the normal-weight aggregate, which takes up

the most space in concrete by volume and mass, was partially replaced with pumice

aggregate, and macro steel fiber (30 mm) was also added to the mixtures. This

experimental work aims to investigate the effect of pumice aggregate amount on the

fresh and hardened properties, as well as the flexural performance of the selfcompacting

lightweight concrete (SCLC). The replacement proportions of pumice

aggregate with crushed sand were arranged as 45%, 50%, and 55% of the entire

aggregate by weight. Three mixtures, each with 1% macro steel fiber reinforcement

and without fiber, were prepared for each mixture scenario. The mix design of these

six mixtures was arranged to achieve the self-compacting ability and the workability

tests recommended by EFNARC (slump-flow, T50, J-ring) were taken into account.

To investigate the mechanical properties (compressive, splitting tensile, and flexural

strengths) and flexural toughness of the samples, the specimens were cured in water

at 23±2 °C for 28 days. As a result, the unit volume weights of the specimens

produced from pumice-substituted mixtures decreased with the increase in the

pumice dosage, while the compressive, splitting tensile, and flexural strengths

decreased. However, it has been determined that all SCLC mixtures including

pumice aggregate provided workability properties in general and had enough

compressive strength to be used in the production of structural bearing elements,

regardless of fiber content. As a result, the optimum pumice aggregate replacement

percentage with crushed sand was found to be 45% and the best flexural performance

values of the specimens having macro steel fiber were observed in the ones having

45% pumice aggregate substitution.