Effect of Ammonium Sulfate and Ammonium Carbonate in Fly Ash on Properties of Mortars
Post-coal combustion process with SCR or SNCR technology is widely used to reduce NOx gas.Both SCR and SNCR technologies involve the process to inject NH3 into the process in order to convert NOx gas to N2.Some unreacted ammonia left in the process can cause ammonia-contaminated fly ash which mostly found in the form of ammonium sulfate and ammonium carbonate.The objective of this study is to investigate the effect of ammonium sulfate ((NH4)2SO4) and ammonium carbonate ((NH4)2CO3) in fly ash on properties of mortars.This research aims to study workability, compressive strength, and shrinkage.Mortar specimens with 30% fly ash replacement and w/b of 0.5 were prepared.The ammonia contamination was done by preparing ammonium salts solution with dissolved ammonium salts in water.The varied concentrations in the test were 0 and 200 ppm (mg of salt/kg of fly ash).The recommended ammonia concentration as the limit for using in concrete from consensus of industry opinions is 200 ppm.This research also investigates the effect of the blending ratios of (NH4)2SO4 and (NH4)2CO3, which are 0, 0.25, 0.50, 0.75 and 1, on the tested mortar properties.The test results show that workability of fresh mortars containing ammonium salts was improved when compared to that of non-ammonium salts mortars.Workability of mortars containing (NH4)2CO3 was higher than that of mortars containing (NH4)2SO4.Setting time of cement pastes containing ammonium salts was delayed when compared to that of non-ammonium salts cement pastes.Setting time of cement pastes containing (NH4)2CO3 was longer than that of cement pastes containing (NH4)2SO4.Compressive strength of mortars containing (NH4)2SO4 reduced when compared to that of nonammonium salts mortars, while the mortars containing NH4)2CO3 achieved greater strength.Autogenous shrinkage of both mortars containing (NH4)2SO4 and NH4)2CO3 were increased when compared to that of non-ammonium salts mortars, while total shrinkage of the mortars containing NH4)2CO3 were reduced.The test results of properties of mortars containing ammonium salts with different ratios of (NH4)2SO4 and NH4)2CO3 were in between that of mortars containing pure (NH4)2SO4 and pure NH4)2CO3.
Fly ash Ammonium sulfate Ammonium carbonate Mortar
S.Roongruangsarn S.Krerkchaiwan W.Saengsoy L.Yongchaitrakul S.Tangtermsirikul
School of Civil Engineering and Technology, Sirindhorn International Institute of Technology (SIIT), Construction and Maintenance Technology Research Center (CONTEC), School of Civil Engineering and Te
国际会议
福州
英文
427-434
2018-11-04（万方平台首次上网日期，不代表论文的发表时间）