Field erosion protection of tidal beach: Comparison and synergy between sulfide aluminum cementing materials and biomineralization materials

The imbalance of sediment transport under the influence of the marine dynamic environment leads to the gradual erosion of the sandy beach. In this paper, a field verification to overcome the issue of coastal erosion affecting the sandy shoreline by two cementing materials, sulfide aluminum cementing materials (SAC) and biomineralization materials, was conducted on the Hainan island in China. Results showed that the treatment process of biomineralization materials and SAC materials determined the protective effect: using SAC materials mixing sand and backfilling first, then spraying biomineralization materials showed basically no protective effect, while spraying biomineralization materials to treat the bottom sand firstly and then using SAC materials mixing sand and backfilling showed excellent protective effect. Using CP, CPM3, M4C treatment methods increased the strength and integrity of tidal sand, thus played a certain role in preventing erosion. However, edge scour was an important issue that cannot be ignored in the application of coastal erosion protection. As a non-destructive rapid test indicator, the rebound strength showed a non-monotonic trend. Due to the degradation of the protective layer caused by erosion, immersion and scour of the tidal dynamic environment, the rebound strength first raised rapidly to a peak value and then gradually decreased. There were three types of cementation: biomineralization in deeper layer of tidal sand, SAC mixing sand and filling in the shallow layer within 10 cm, interface bonding between biomineralization layer and SAC mixing sand and filling layer.