Study On The Working Performances And Behavior Mechanisms Of Potassium Magnesium Phosphate Cement Fire Prevention Board

With the vigorous development of social economy and building industries,public consciousness of fire prevention and environmental protection is increased.Fire prevention board has been adopted to improve the capacity of building fire protection,because of its convenience to be use.In order to satisfy the public demand for fire prevention and environmental protection,a new type of inorganic fire prevention board is developed in this research.Potassium magnesium phosphate cement(MKPC)has excellent properties of high temperature resistance,high early strength,good volume stability and high bond strength.Thus it is very suitable for the preparation of fire prevention board.To give full play to the advantages of MKPC,this research firstly attempts to use MKPC for the development of fire prevention board.Firstly,the activity of magnesia powder is controlled to prepare MKPC with stable performance.Then,appropriate net pulp ratio of MKPC is selected for the preparation of potassium magnesium phosphate cement fire preventi on board(abbreviated MKPC fire prevention board and fire prevention board for short).Finally,a series of single and double mixing experiments selecting the flexural strength,duration of fire resistance,apparent density as main indexes are conducted to study the basic performance and its optimization of MKPC fire prevention board with different mix ration.The laws of performances changing with the mixing proportion are found to guide the proportion design of MKPC fire prevention board.The test results of simultaneous thermal analysis,pore structure,SEM and macro tests are combined to analyze the behavior mechanisms.The main conclusions are as follows:1.The magnesium oxide powder calcined with longer time and higher temperature has better crystallization degree,smaller specific surface area and less reactivity under the conditions of the experiments,using citric acid neutralization method to measure the reactivity of magnesium oxide powder.If the reaction solution temperature and neutralization time of 2.0 g sample could match the formula of T ?14.32-0.34t(T represents time,t represents temperature),the activity of magnesium oxide powder is suitable to prepare MKPC with appropriate performance;2.when the quality ratio of KH2PO4 and magnesium oxide(MgO)(P/M)is 1/3,the flexural and compressive strength are best and refractory performance is satisfactory.MKPC with P/M= 1/3 is a suitable adhesive material for preparation of fire prevention board;3.With the increasing dosage of refractory insulation materials,the refractory insulation performance of fire prevention board is improved,the fire endurance time is increased,but the flexural strength and apparent density are decreased;4.Silica fume can improve the work performance of fire prevention board obviously,increase the compactness and improve the flexural strength of fire prevention board,and has little effect on the refractory insulation performance or apparent density of fire prevention board;5.PVA fiber,aluminum silicate fiber,glass fiber interacted with the adhesive cementation material can significantly improve the flexural strength of the fireproof board.But PVA fiber is easy to be thermal decomposedto form the communication hole in the board,Thus it would weaken the thermal insulating ability of fire prevention board;6.MKPC contains a lot of MgKPO4 · 6H2O,that leads to the high moisture content of fire prevention board.However,when heated,MgKPO4 · 6H2O will absorb heat and take off crystal water,and greatly retard the heating speed on the back of fire prevention board,and it is helpful to prolong the fireproof time of the board.