| Along with the increasing application of sulphoaluminate cement concrete in marineconcrete engineering, the surface of sulphoaluminate cement concrete was often attached to alarge number of marine fouling organisms.Barnacles was the most dominant species of thesefouling organisms.Studies found that adhesion of marine organisms had an impact on thesurface structure of marine engineering and durability.This subject mainly studies theinfluence of the barnacle adhesion and the cement changes about surface physicochemicalproperties, mechanical properties,surface impermeability and anti-carbonation properties. Theresults showed that:1.Yeast powder, sugar and peptone had little effect on barnacle adhesion, while naturalmarine environment plays an important role in barnacle adhesion, Suitable growth temperature is20℃~28℃reproduction, seawater pH ranged from7.9to8.4. Barnacles can adhere to the surfaceof most of the marine construction,the thickness of Barnacles chassis varies due to thesubstrate and the Barnacles chassis thickness of concrete, stone, red brick, hollow brick wereabout400μm,300μm,100μm and100μm,respectively.The Barnacles chassis of stone andconcrete is dense, while the Barnacles chassis of red brick and hollow brick is loose. Themain functional groups of barnacle colloid were the amino (-NH2), carbonyl (C=O) and-C-N,-(CH2)n, n≥4, testing by infrared spectrum analysis.2. Barnacle larvae easily attached to the high surface energy substrates. The surfaceenergy of sulphoaluminate cement of unhydrated6h was51.46mJ·m-2and the hydration onewas58.26mJ·m-2.The surface free energy gradually increased with the hydration proceedsgoing on. The surface free energy of ordinary portland cement unhydrated and hydration6hwere49.37mJ·m-2and56.32mJ·m-2.Under the same hydration time, surface free energy ofsulphoaluminate cement was higher than that of ordinary portland cement.3.The concrete surface was covered with biofilm layer which was consist of the Balanusouter shell, the Balanus underlying and biological glue. Balanus underlying was mainlyconsists of C,O,Ca. The natural calcareous layer of protection was very compact. Thebiological glue was mainly consists of C,N,O and10μm~20μm thick. The biological gluepenetrated into the pore structure of concrete surface voids. The C30and C50concrete surface porosity were decreased by4.9%and8.6%by Barnacle adhesion.The C30concretepore volume of100μm~200μm and50μm~100μm were respectively21.52×10-3ml and3.69×10-3ml through the simulated seawater erosion, but they was respectively2.4×10-3mland20.05×10-3ml through the natural seawater erosion. The volume of natural seawaterconcrete surface pores increases, and the aperture were more refinement.4.The sulphoaluminate cement concrete test block were eroded for six months.Thestrength of C30concrete with fresh water, seawater and seawater erosion were39.3MPa,41.6MPa and42.3MPa,respectively. The strength of C50concrete with fresh water, seawaterand seawater erosion were51.8MPa,56.5MPa and58.3MPa, respectively. Barnacle adhesionhad no obvious effect on mechanical properties of concrete. The permeability time of C30concrete through the freshwater, simulated seawater and natural seawater were263s,922s and958s,respectively.The permeability time of C50concrete through the freshwater, simulatedseawater and natural seawater were1066s,1821s and1934s, respectively.The antipermeability of C30and C50were increased by4%and6.2%after Barnacle adhesion.ForC30sulphoaluminate cement concrete,7d carbonation depth through Natural seawatererosion is1.6mm, and28d carbonation depth is5.6mm,increasing250%.7d carbonation depththrough Simulated seawater erosion is3.4mm, and28d carbonation depth is8.3mm,increasing144.1%.7d carbonation depth decreased by52.9%,28d decreased by12.5%with Barnacle adhesion. Barnacle adhesion can improve the anti carbonation propertiesof sulpho aluminate cement concrete, especially in the early stage. |
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