Investigating the Potential Use of Tuff Aggregates to Produce Lightweight Concrete

Abstract

Lightweight concrete can be made by using either artificial lightweight aggregates or natural lightweight aggregates. Artificial lightweight aggregates include expanded clay, ground blast furnace slag, slate, and shale. Natural aggregates include; tuff, pumice, scoria, rhyolite, and perlite among others. The rapidly increasing cost of production of artificial lightweight aggregates has however renewed the interest in the research and use of naturally occurring lightweight aggregates. The current study, therefore, assessed the performance of lightweight concrete made from crushed tuff aggregates while comparing its properties with those of conventional concrete. The procedure outlined in ACI Code was used for concrete mixed design. Some of the results obtained include the average 28-day unit densities of 2038 kg/m3 and 2527 kg/m3 for tuff and conventional concretes respectively. The compressive strength tests were performed at different ages of concrete following BS 1881-part 116. Specifically, the 28-day compressive strengths of 26.0 MPa and 30.0 MPa were obtained for tuff and conventional concretes respectively when presoaked aggregates were used with a water-cement ratio of 0.4. There was an increase in the 28-day compressive strength of tuff concrete while a continuous decline in the compressive strength of conventional concrete was noted when the w/c ratio was increased. It was noted in the current study that the production tuff concrete is less costly and economical than NWC. The study further confirmed that tuff aggregates can produce concrete with a splitting tensile strength of 2.9 MPa and elastic modulus of 10.6 GPa. Tuff concrete mixed designs were done according to ACI Code. This concrete is recommended for floor-filling in high-rise buildings. The study, however, did not cover durability tests on the concrete samples but recommended the same to be investigated in future studies.