Research On Life Cycle Environmental Impact Assessment Of Recycled Straw Wall Materials

Straw is a biomass resource with multiple uses.However,about 70%of the total amount of straw in China is burned in the field,thus causing serious environmental pollution and waste of resources.Driven by the national wall material reform and energy-saving building policies,China's new wall materials are developing rapidly.Straw building board not only has the advantages of light weight,high bending strength and good thermal insulation performance,but also has broad application prospects in the construction industry.Domestic research on straw wall materials mainly focuses on product performance,but for the environmental load status of the whole life cycle of the board produced with straw as raw material,the advantages and disadvantages of the comparison with environmental load of the traditional wood board and straw open-air burning mode still need to be studied.This paper first focuses on the principles and basic operating steps of the Life Cycle Assessment(LCA).The raw material ratio design and production process of two kinds of straw wall materials were analyzed.On this basis,we collect,integrate and analyze the input and output data of inventory analysis in straw board,which lays a foundation for the comprehensive quantitative analysis of the environmental impact of straw board and even its life cycle;in addition,a comparative study with traditional wood board and straw open burning methods is conducted to qualitatively and quantitatively analyze the energy consumption and environmental load at various stages of the life cycle,and the process links that have the greatest impact on the environment are identified during the production process;the eBalance software is used to construct a life cycle impact assessment method suitable for straw boards,from resource consumption(depletion coefficient),greenhouse effect(GWP),acidification effect(AP),water eutrophication(EP),photochemical smog(POCP)and human body impact assessment of six aspects of health damage(HTP);on this basis,the Monte Carlo Crystal Ball software is used to perform a sensitivity analysis on the contribution rate of key parameters to the overall system environmental impact,and the contribution rate of the key parameters to the system environmental performance is obtained;.Finally,from the perspective of production technology and pollution prevention and control,some reference suggestions are proposed to improve the environmental performance of straw wall materials.The research results show that the total energy consumption of the life cycle of 1m3 straw man-made board is 3125MJ,the total potential environmental impact value is 4.84E-11,and the wood-based board is 5%and 9%higher than it.The most serious environmental impact is GWP,accounting for 41.41%of the total potential value;the total life cycle energy consumption of 1m3 straw cement composite board is 5622MJ,the environmental impact potential value is 6.70E-11,and the relative size of environmental impact is GWP>EP>AP>POCP>HTP;compared with the traditional way of straw(open burning),the environmental impact of straw burning in the greenhouse effect,acidification effect or particulate matter emissions is far greater than the plan of making straw into plates,but straw burning also has a positive effect on soil fertility;in the straw board system,the straw transportation distance,the power consumption of the board forming process and the power consumption of the straw processing process have the largest contribution rate,which is the main factor affecting the environmental performance of the system;in the straw cement composite board system,power consumption in the process of molding,straw transportation distance and OPC transportation distance are the main factors;the raw material preparation,drying and hot pressing processes are the two energy-consuming processes of the straw board life cycle.By formulating reasonable preparation,drying and hot pressing processes,the dryer and the working efficiency of the hot press will greatly reduce the environmental load of the straw board;various performance indicators of the straw board meet or exceed the wooden board,and the straw board has excellent thermal insulation performance,fire resistance performance,sound insulation performance and so on,which can be replaced wood to protect the ecological environment.