Species abundance of three mortar mixes deployed subtidally for 12 months

Bone, Jessica R. (2024) Species abundance of three mortar mixes deployed subtidally for 12 months.

We aimed to determine how bioreceptive lower-carbon cements (Vicat Prompt and GGBS) were compared to control cement (OPC) and how this changed over time. Two low carbon mortars (Mortar 1 ‘GGBS’ - CEMIII/B cement, 60% ground granulated blast furnace slag by Ecocem Ireland Ltd., 40% ordinary Portland cement; mortar 2 ‘VP’ - a natural Roman binder, brand name Vicat Prompt) were trialled alongside a control mortar comprised of 100% ordinary Portland cement (‘OPC’, CEMI 52.5R cement, brand name Blue Circle Snowcrete). The mortar mixes comprised of binder at a 1:1 weight ratio with silica sharp sand (0-4 mm, sourced from Travis Perkins PLC.), and 1:2½ cement to water weight ratio. A retarder was added to the VP mortar according to manufacturer guidance to increase the setting time enough to pour the mixture into the moulds. The mortar mixes were hand-mixed and poured into silicone moulds to aid release of the cast blocks and avoid use of releasing agent. The silicone moulds produced mortar blocks with the dimensions 20 x 40 x 80 mm. Sixty replicate blocks were produced for each mix and cured in an indoor environment for the appropriate minimum time as recommended for each cement. Once cured, twelve replicates of each blend were fixed to a plastic crate, elevated and separated by 10 mm width plastic trunking to permit adequate water flow around each block and avoid biotic contamination with its neighbour. total of six crates were set up with three crates deployed at each of the two study sites in June 2021; Poole Harbour, Dorset, UK (50.708745, -1.9863721, What3Words rungs.safely.range) and Hamble Harbour (50.852506, -1.3079996, What3Words bought.haggis.desiring), Hampshire, UK. The crates were deployed subtidally, suspended at least 1 m from the surface and seabed. A short video briefly showing block production and crate deployment may be viewed here (youtube.com/shorts/UnsPqyXc-Ko).