| Paper mill sludge has many problems,such as large reserves,difficult disposal and secondary pollution.In order to realize the recycling of paper mill sludge,this paper used paper mill sludge as the main raw material to prepare new lightweight ceramsite,and then uses the lightweight aggregate to prepare lightweight self-thermal Insulating wall blocks for green building.The main conclusions are as follows:（1）The best preparation conditions and properties of paper sludge ceramsite were determined.The optimal proportion of paper-making sludge ceramsite was determined as follows,paper-making sludge:clay:fly ash=30:49:21.At this time,the expansion ratio of ceramsite is the best,and the morphology of ceramsite is good.And the best preparation conditions were also obtained as follows:the pretreament temperature was 300～400℃,the pretreatment time was 5～25 min,the sinter temperature was 1230℃,and the sinter time was 8min.Under this pertreatment condition,the complete carbonization of raw pellets were realized,the cracking and caking of ceramsite was effectively avoided because the organic matter and water contained in paper-making sludge were uneven heated in the sintering process.Under this condition,the characteristics of prepared sludge ceramsite were as follws:the expanded ratio of the prepared paper sludge ceramsite was 1.93,the bulk density was 633 kg/m3,the cylinder compressive strength was 3.1 Mpa.（2）The preparation mechanism of ceramsite from papermaking sludge was discussed.The organic matter in the sludge which was produced into carbon after preheating treatment released gas in the sintering process,which promoted the volume expansion of ceramsite.By adjusting the sintering temperature,the speed of gas generation was controlled,and then the expansion ratio of ceramsite was controlled to avoid cracking.Calcium oxide in papermaking sludge acted as a flux,which reduced the sintering temperature of ceramsite.With the increase of paper-making sludge content,the sintering temperature of ceramsite decreased,the pore diameter decreased,the density increased and the cylinder pressure strength increased.The content of"Si O2+Al2O3"in papermaking sludge was low.When the amount of sludge was too large,the morphology and structure of the product would be difficult to maintain in the moltenstate due to the lack of skeleton.In order to achieve a higher amount of paper-makingsludge and maintain the morphology of ceramsite,clay and fly ash with high silicon and aluminum content needed to be introduced as ingredients.（3）The best preparation conditions and properties of self insulation lightweight wall block were determined.When 0～5 mm fine aggregate and 5～20 mm coarse aggregate were saturated 24hours by pre wetting treatment,the wall blocks with good performance were produced as follows:cement 264 kg/m3,fly ash 66 kg/m3,ceramsite fine aggregate 493 kg/m3,ceramsite coarse aggregate 431 kg/m3,pre wetting water 107 kg/m3,mixing water 103kg/m3,polycarboxylate superplasticizer 8.25 kg/m3.Under this condition,the characteristics of the wall blocks were as follws:the compressive strength was 5.2 MPa,the apparent density was 1020 kg/m3,the water absorption was 14.2%.Performance of the wall blocks was tested and analyzed,which meeted the performance requirements of self insulation block. |
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