Mixture Design Development and Performance Verification of Structural Lightweight Pumice Aggregate Concrete

Naturally occurring lightweight volcanic pumice aggregate was used for the development of structural lightweight concrete. The primary aim of the investigation was to reduce both the economic costs and the negative environmental effects that are typically associated with production of conventional lightweight concrete containing artificially produced aggregates by taking advantage of New Zealand’s abundant pumice resources. Mixture designs were developed for concrete containing both partially saturated and fully saturated pumice aggregates, achieving compressive strengths up to 40 MPa while maintaining unit weights below $1,850\mathrm{kg}/{\mathrm{m}}^3$. A vacuum saturation system was developed to completely saturate the normally partially saturated aggregates, which was necessary to avoid a loss of workability and to alleviate complications with mix-water calculations that occurred for concrete containing partially saturated pumice aggregates. Experimental investigations into the bond strength and shear strength of pumice concrete were also conducted. The results showed that the mixtures developed outperformed both the bond and shear strength requirements for structural lightweight concrete of the New Zealand Concrete Structures Standard NZS 3101:2006. The research presented demonstrates the effective and innovative use of New Zealand’s abundant resources of naturally occurring pumice aggregates for producing structural lightweight concretes that meet the requirements of New Zealand concrete structures standards.