The Application Of Green Mud From Papermaking Industry On Green Building Materials

With rapid development of industry globally,people's living standards are enhanced increasing.Meanwhile,there is large amount of solid waste produced to pollute the surroundings.With the strategy of sustainable development's coming into being and people's enhanced consciousness of environmental protection,the recycle treatment of solid waste draw much attention of the public.Nowadays,recycling the solid waste is also one of the effective way in construction industry.The solid waste,green mud,of paper mill's was investigated in this dissertation.More specifically,the basic properties of green mud were comprehensively assayed by the method of XRF,XRD,TG and SEM.Then,green mud was replaced by cement and standard sand to study the effects of green mud on cement paste and the properties of mortar and to investigate the slumming's inhibition.Simultaneously,further research was made on optimal conditions of banana stem fiber cement board and the effects of green mud on the properties of the cement board.The main conclusions were as follows:The main constituent of green mud was calcium carbonate(CaC03),which density was lower than cement.Therefore,these particles could agglomerate together.Most of single particle with size distribution below 100 ?m,appeared to be sphere.The main properties of cement paste include water requirement of normal consistency,consolidating time and compressive strength.After cement was replaced by green mud,we found an obvious influence of green mud on the properties of cement paste.When the mix-ratio of green mud was below 20%,water requirement of normal consistency was basically unchanged while when the mix-ration of green mud was above 20%,water requirement of normal consistency decreased significantly,from which could we accordingly concluded that the mix of green mud could prolong both initial and final consolidating time of cement paste.However,the increment was not obvious,which met the demands of GB.In addition,the compressed strength after cement paste's 7-day and 28-day blocking would show an upward trend at first,but descend afterwards with the addition of green mud.When the addition of green mud accounted for 15%,the compressed strength could reach the top.Besides,the strengths after 7-day and 28-day blocking were 37.44 MPa and 54.69 MPa,respectively.Another conclusion could be concluded that green mud affected the strength of cement in early period more from SEM characterization.The effects of green mud on mortar by using green mud to replace standard sand were also investigated.The results indicated that the addition of green mud would reduce the property of mortar,but only little.When the amount of substitution accounted for 10%,the mobility of mortar was 190 mm and the compressed strengths after 3 days and 28days were 19.04 MPa and 33.08 MPa,respectively.Main possibility of slumming in the blocked cement mixed with green mud might attribute to soluble salt in green mud.Therefore,the green mud must be dealt with by water.Accordingly,the optimal conditions of water-washing were determined as the ratio of green mud and water 1:2,stirring time 1 h.The results could succeed in inhibiting the form of slumming apparently.The orthogonal experiments were also conducted.Therein,the ratio of water and green mud(RW:G)and the ratio of fiber and green mud(RF:G)were chosen as variables to investigate the optimal condition of manufacturing banana stem fiber cement boards.The results indicated that when RW:G was too low,the static bending strength would rise with the augment of RF:G while the static bending strength would drop when RW:G was too large.Ultimately,the optimal conditions were determined as RW:G 0.3,RF:G 0.4.Under these conditions,the density of fiber cement board was 1.62 g/cm3 and the static bending strength was 10.85 MPa,which could meet the requirements of superior products of national standards.