Strengthening Rabaul Volcanic Ash (RVA) Cement Compressibility with the Addition of Lime

Abstract

Lime comes from burnt limestone (calcium oxide), and sea shells (calcium carbonate) which were mixed in concrete used for a dense building material but lost its favor when Portland cement come into existence. Lime from sea shells was common in Papua New Guinea; it is used together with chewing buai, a traditional betel nut used by locals for alertness, increased stamina, and a sense of well-being. The lime was used as an additive to help boost the strength of RVA (Rabaul Volcanic Ash) cement (in natural state) studied by Betasolo, Lelepo, and Kaurea in 2013 by partial substitution of 50%, 70% and 100% to that of Ordinary Portland Cement (OPC). Although lime in concrete is not new, lime added to volcanic ash from Rabaul, one of Papua New Guinea’s town hit with a catastrophic volcanic eruption that wipes out the city, is new in the context that RVA has different properties than other ash in the world. The low compressive strength motivates the authors to study further by adopting a 25% partial substitution of RVA to that of OPC used as cement. The new proportion increases by 75% from the previous experimental result. The addition of lime shows to increases the compressive strength of cement paste by 204% making it nearly equal in strength to that of the OPC. The discovery proves that RVA as cement can minimize carbon footprint in cement production. It will provide government and entrepreneur’s idea to make use of the vast RVA resource, to rebuild the lost city that was once a tourist destination of Papua New Guinea, and further studies can emerge to commercialize a product that may come from it.

Keywords: lime, RVA, Rabaul Volcanic Ash, cement, compressive strength, strengthening cement paste