Research On The Experiment And Mechanism Of Clay Bricks Reinforced By Hydroxyapatite

As a kind of traditional building materials,brick has remarkable achievements in historical orientation and geographical dimension.Outside the brick materials used in construction decoration has a long history,from as far away as one thousand years ago the walls,towers and palaces,private garden of Ming and qing dynasties,local-style dwelling houses building,close to the current cultural buildings such as museums,libraries,etc.,are heavy use of blue bricks,such as red brick material as the foundation structure.And a long brick structure building materials use fixed number of year,because brick material inside there are a large number of small open pore,with strong water imbibition,when the water saturation and negative temperature in winter,the porosity of the complete side wall surface will produce microcrack,easy pulverization,cracking and peeling symptoms.How to protect and reinforce the brick structure is an important task in engineering.In this paper,on the basis of sintered clay brick,by different concentration of calciumchloride,?calciumchloride,CaCl2?anddiammoniumphosphate,?Diammonium Phosphate,DAP,?NH₄?₂HPO₄?solution is a circulation process of 28days of sintered clay brick,and 0.5 mol/L of calcium chloride and ammonia solution of hydrogen Phosphate with different cycle approach to 30 days after sintered clay brick experiment,the bibulous rate of each sample were as well as the change of the compressive strength.Using scanning electron microscopy?SEM?and energy spectrum analysis?SEM/EDX?and X-ray diffraction spectrum?XRD?was carried out on the sample of micro morphology,element distribution and crystal analysis,research of different concentration of DAP and cycles on sintered brick the differences between the reinforcement effect and strengthen the mechanism of sintered brick DAP.The main work and conclusions of this paper are as follows:1)The water absorption rate of sintered clay bricks after immersed for 28 days in0.5 mol/L,1 mol/L,2 mol/L calcium chloride and DAP solutions was reduced by 23%,41%,and 58%,respectively,compared with ordinary sintered clay bricks.The compressive strength increased by 27%,36%,and 43%,respectively.2)After 10 cycles of soaking for 30 days with 0.5 mol/L calcium chloride and DAP solution for 30 days,the water absorption of the sample decreased by 65.7%and the strength increased by 55.9%.After five cycles of soaking for 30 days with 0.5mol/L calcium chloride and DAP solution soaked for 6 days,the water absorption of the sample was reduced by 22.7%and the strength was increased by 25%.3)Microscopic characterization tests showed that the micro-morphology of the sintered bricks soaked in calcium chloride and DAP solution changed significantly.SEM and XRD confirmed that the sintered bricks were immersed in the calcium chloride solution,which caused free adsorption on the surface and internal pore cracks.Calcium ions,these calcium ions will dissolve in the water complex reaction with DAP,generate phosphorus-containing hydroxyapatite HAP precipitation,HAP formation and crystallinity with the increase in the concentration of DAP solution increases.4)The microscopic analysis of the micro-mechanism of the DAP-reinforced sintered bricks was obtained by microscopic analysis.The calcined bricks were immersed in a calcium chloride solution and adsorbed free calcium ions at the surface and internal pore cracks.When the bricks were freed with calcium ions,they were dried.When immersed in DAP solution,these calcium ions will dissolve in the water and react with the phosphate in the DAP solution under alkaline conditions.HAP precipitates in the surface pores and internal pores of the brick,fills the pores,and strengthens the gaps.Knot,and because of its unique nano-network structure,intertwined with each other to form a stable reinforcement structure,thus enhancing the compressive strength of sintered bricks.In summary,the use of DAP as a reinforcing agent and calcium chloride as a supplemental calcium source can effectively reduce the water absorption of the fired bricks,and increase the compressive strength of the fired bricks,thereby improving the durability and strengthening and protecting the clay bricks.To the beneficial effect.