Study On The Physical And Mechanical Properties Of Shell Lime-the Ancient Chinese Building Material

The main components of shells are about 95% calcium carbonate(CaCO3)and a small amount of chitin.The ancients used shells to make shell lime which was used as building cementitious materials.Shell lime has long history in China's southeastern coast,and widely distributed.Many ancient buildings along the southeast coast have used shell lime as gel materials.The purpose of this paper is to fully understand the properties of shell lime as building materials and to serve the protection and restoration of ancient buildings.In this paper,the distribution,history,firing technology,mineral,chemical composition,microscopic and physical properties of the shell lime of ancient buildings were studied.The shells from Xiamen city of southeast coastal Fujian Province were calcined in the laboratory to produce shell lime,and their mineral and chemical composition were studied.The physical and mechanical properties of shell lime under different sand cement ratio and water cement ratio were compared.In particular,the paper also studied the effect of glutinous rice slurry on the physical and mechanical properties of shell lime.The conclusion of this paper is as follows:(1)Calcium carbonate is the main component in the shell lime samples of ancient buildings,accounting for about 50%-90% of the total,and it contains organic compounds,which may contain glutinous rice paste.Small cracks can be observed in the shell lime samples,some of which are linear and some are reticular;(2)The shell lime prepared by calcining the shell with clay minerals contains the hydraulic component ?-calcium silicate(?-CS),and the content of ?-CS is the most at 1000 ?;(3)The shell lime samples with S / L = 1:2 and W / L = 0.6 have stronger resistance to softening and disintegration,the largest shear strength and the fastest growth rate of shear strength;the samples with S / L = 2:1 and W / L = 0.6 have the best compressive strength properties;(4)After adding glutinous rice pulp,the water content of shell lime decreased,the durability increased,and the shear strength and compressive strength increased significantly.