Impacts from Waste Oyster Shell on the Durability and Biological Attachment of Recycled Aggregate Porous Concrete for Artificial Reef

Abstract

Poor biological attachment of artificial reef (AR) prepared by the recycled aggregate limit the application in the area of marine engineering. In this study, the waste oyster shell (WOS) was used as raw materials to prepare the recycled aggregate porous concrete (RAPC), the compressive strength, split tensile strength, chloride penetration resistance, freezing-thawing resistance, low temperature resistance, and the biological attachment were tested, aiming to improve the biological attachment and decrease carbon dioxide emission. The experiment results demonstrate that the use of WOS can decrease the compressive and split tensile strength, but the effect of designed porous structure on the mechanical strength is higher than that of WOS. To ensure the durability of RAPC, the contents of WOS should not exceed 20%. Additionally, the addition of WOS and designed porous structure are beneficial to biological attachment. However, the porous structure of RAPC only improves biological attachment in the short term, and the reverse phenomenon is true in the long term. As the partial replacement of cement with WOS is 40%, the total carbon dioxide emission decreases by about 52%. In conclusion, the use of WOS in the RAPC is an eco-friendly method in the artificial reef (AR) with improved ecological attachment and reduced carbon dioxide emission.

Coral recruits on concrete hemispherical artificial reef (HSAR) with different composition in Pasir Putih, Situbondo, Indonesia

“…Based on this result, the addition of CSW may not have significant positive effect on the coral larval settlement. A relatively similar finding was shown by [7], in which porous structure may be beneficial to biological attachment only in short term and the reverse result occurred in the long term.…”

“…The application of HSAR in the study is to provide a sturdy and suitable platform for larval settlement [3]. The addition of CSW in C2 and C3 intended as a substitute for coarse aggregate (gravel) [3,4]; even though this will decrease the compresive and split tensile strengh of the concrete [7,22] and increase the porosity of the concrete [7] thus increasing contact between the concrete surface and the seawater. Shell waste also contains calcium carbonate and is estimated to be a source of calcium for coral biomineralization or calcification processes.…”

“…Calcium content in concrete AR will leached when submerged in seawater [5] and is estimated to be a source of calcium for coral biomineralization processes. AR is man-made structure deliberately introduced or submerged on the seafloor for the purposes to provide suitable habitat for marine organism and enhance fisheries as well as for shoreline protection [6,7]. In addition to shell waste, fly ash-bottom ash (FABA) resulted from coal combustion can also be used as an additional or substitute material in the cement mixture for AR; either as substitutes for aggregates or the cement itself.…”

Use of Seashell as Cement Replacement in Construction Material: A Review

“…Realizing the importance of a cleaner environment, researchers have integrated seashells namely cockle shell, oyster shell, clam shell, queen scallop and mussel shell as the replacement materials for concrete ingredients as shown in Table 1. Malaysia Cockle Cement and filler replacement [28] Indonesia Ground cockle Cement replacement [7] Nigeria Oyster Seashell Cement replacement [29] Palestine Clam Seashells Cement replacement [30] India Mixed Seashells Cement and aggregate replacement [31] China Oyster Seashell Recycled aggregate porous concrete for artificial reef [32] France Queen Scallop Replacement for metakaolin [33] India Clam Seashell Coarse aggregate replacement for basalt fibre-reinforced concrete [34] Malaysia Anadara Granosa Sand replacement in mortar [35] South Korea Cockle Shell Pervious concrete pavement [36] China Mussel shell Replacement of aggregate…”

Effect of gelatin powder, almond shell, and recycled aggregates on chemical and mechanical properties of conventional concrete

“…Their results show that the compressive strength increased more than 20-46% with adding different percentages of Bambara nutshell ash. Kong et al [15] investigated adding the waste oyster shell on the recycled aggregates concrete. They examined the compressive, and flexural strength.…”