Urea blocks. I. Methodology of block making and different formulae tested in Syria

[摘要] ThreetestswerecarriedoutfromMaytoOctober1991tomakeurea-blocksusingavarietyofagriculturalby-productsandbinders.Solvent-extractedolivecake(20to35%)withandwithoutscreenedpoultrylitterwasusedinTest1.Theeffectofbinderwasestablishedinthesecondpartofthistest.InTest2,molasseswasaddedtotheformulationusingsevendifferentproportions(0,5,10,15,20,30and40%).Theeffectofthetypeofbinder(cement,slakedlime)eachatthreedifferentlevels(0,4and8%),wasstudiedinafactorialarrangementoftreatmentsforblockscontainingareducedlevelofmolasses(Test3).Gypsum[CaSO4.1/2H2O]wasfoundtobeagoodbinderinTest1;however,inpart2ofTest1,itproducedblocksoflesshardnessandcompactnessthanwhenslakedlime[Ca(OH)2]wasused.Tenpercentcementinaformulawithoutanymolassesorpoultrylittergavegoodblocks,whereaswhenpoultrylitterwaspresent,theblockswereofmediumhardnessandcompactness.Increasingthelevelofcementwasfoundtoproducegoodblocksevenatthepresenceofpoultrylitter.Intheformulaewithoutmolasseslargerquantitiesofbinderandwaterwererequired(Test2).Thesametestshowedthatblockscanbemadewithorwithoutmolassesandthateven5%molasseswassufficientformakinggoodblockswithlowlevels(6%)ofslakedlime.InTest3,theadditionofaslittleas4%slakedlimegaveverygoodblockswhenmolasses(20%)waspresent.Ingeneral,formulaecontainingcementwerefoundtobelesshardthanthosewithlime.Thedensityofblockswasfoundtodecreasewithdecreasingmolassescontentandalsowithincreasinglevelsofbulkymaterials.Itisconcludedthatblockscanbemadewithandwithoutmolasses;slakedlimeisabetterbinderthangypsumandselectionbetweenslakedlimeandcementshoulddependonavailabilityandprice.Theorderofintroductionoftheingredientsseemstobelessimportantthanwaspreviouslythought.

[学科分类] 农业科学（综合）