Feasibility Study Of 3D Printing Artificial Reef Concrete

Artificial reef is an artificial facility used for repairing and optimizing the Marine ecological environment and constructing the living field of Marine aquatic life.It is also a basic ecological project in the construction of Marine pasture.How to choose reef building materials is directly related to the construction effect of artificial reef.Concrete is the most widely used reef building material due to its plasticity and durability.The traditional artificial reef concrete is made of formwork,and the dust in construction site is serious and pollutes the environment.With the progress of science and technology,3D printed concrete technology has gotten rid of the formwork limitation in traditional concrete construction and provided a new idea for the complex design of artificial reef.This paper analyzes the compressive performance,pH,biological adhesion performance and economy of 3D printed artificial reef concrete,so as to preliminarily explore the feasibility of 3D printed artificial reef concrete.The main results are as follows:(1)Under the three printing paths of parallel,staggered and concentric circles,the compressive strength of the test block is higher than 35 Mpa.The compressive strength of the 3D printed artificial reef concrete test block printed by concentric circles is the highest in the X,Y and Z axis directions,which is 54.53 Mpa,55.58 Mpa and 57.23 Mpa,respectively,higher than the other two paths.The test block with staggered path was cured under different conditions.The results showed that the compressive strength of the test block after 14 days of curing was higher than that after 7 days of curing.The compressive strength of the test block after 14 days of curing with fresh water was the highest,which was 56.06 Mpa for X axis,53.41 Mpa for Y axis and 54.57 Mpa for Z axis,respectively.(2)After soaking in seawater,the pH value of 3D printed artificial reef concrete test block was generally stable between 7.50 and 8.50,and showed a trend of rising first and then decreasing with the extension of time.There was a significant difference in the pH values between seawater and fresh water curing conditions after soaking in seawater.After 14 days of fresh water curing,the pH values of the test block basically remained between 8.00-8.50,with the highest pH of 8.45 and the lowest pH of 8.05.After 14 days of seawater curing,the pH values of the test block basically remained between 7.90-8.30 and the highest pH of 8.23.The lowest is 7.98.(3)Biological adhesion tests were carried out on 3D printed artificial reef concrete test blocks printed with 10 mm and 20 mm print heads respectively.The results showed that there were three dominant species in the two 3D printed artificial reef concrete test blocks and control blocks,namely,Littorina brevicula,Homalopoma sp.and Pagurusgracilipes.There was a significant difference in the amount of biological attachment between the test blocks with two different groove depths formed by two printing heads of different specifications and the control group(P<0.05).The 3D printed artificial reef concrete test blocks printed with 20 mm printing heads had the most attached biomass.(4)The economic benefits of two different construction methods are compared with the artificial reef project in the first phase of Marine pasture demonstration area near Dachangshan Island,Dalian City,Liaoning Province.The results show that the construction cost of 3D printed artificial reef concrete is 21.37% lower than that of traditional cement-based materials.Compared with the traditional cement-based material construction project,the construction site personnel of 3D printing artificial reef concrete technology are reduced by 37.5%,and the labor cost is greatly reduced.Traditional cement base material in construction technology,the design of the template,prefabrication,support,demolition,cleaning process is inevitable,especially in the abnormal blocks construction,need a lot of personnel and time,the template turnover also needs strict design,3D printing perfect to avoid this defect,make the progress by 21%,the curing time is better than the traditional cement base material to reduce greatly.