We experimentally studied the interaction between pozzolanic material（fly ash） and dehydrated autoclaved aerated concrete（DAAC）. The DAAC powder was obtained by grinding aerated concrete waste to particles fi ner ...We experimentally studied the interaction between pozzolanic material（fly ash） and dehydrated autoclaved aerated concrete（DAAC）. The DAAC powder was obtained by grinding aerated concrete waste to particles fi ner than 75μm and was then heated to temperatures up to 900 ℃. New cementitious material was prepared by proportioning fly ash and DAAC, named as AF. X-ray diffraction（XRD） was employed to identify the crystalline phases of DAAC before and after rehydration. The hydration process of AF was analyzed by the heat of hydration and non-evaporable water content（Wn）. The experimental results show that the highest reactivity of DAAC can be obtained by calcining the powder at 700 ℃ and the dehydrated products are mainly β-C2 S and CaO. The cumulative heat of hydration and Wn was found to be strongly dependent on the replacement level of fl y ash, increasing the replacement level of fl y ash lowered them in AF. The strength contribution rates on pozzolanic effect of fl y ash in AF are always negative, showing a contrary tendency of that of cement-fl y ash system.展开更多
Since last two decades,the Portland Pozzolane Cement(PPC)is extensively used in structural concrete.But,till to date,a few literature is available on bond strength of concrete using PPC mixes.There are many literature...Since last two decades,the Portland Pozzolane Cement(PPC)is extensively used in structural concrete.But,till to date,a few literature is available on bond strength of concrete using PPC mixes.There are many literatures available on bond strength of concrete mixes using Ordinary Portland Cement(OPC).Hence,a comparative study was conducted on bond strength between OPC and PPC mixes.In the present investigation,total 24 samples consisting of M20,M35 and M50 grades of concrete and 16 and 25 mm diameter of TMT bar were tested for 7 and 28 days.The pullout bond test was conducted on each specimen as per IS:2770-1967/1997[1]and the results were observed at 0.25 mm slip at loaded end called as critical bond stress and at maximum bond load called as maximum bond stress.It was observed that the critical bond strength of PPC mixes is 10%higher than OPC mixes.Whereas,marginal improvement was noticed in maximum bond strength of PPC mixes.Hence,based on these findings,it could be concluded that development length for PPC mixes could be reduced by 10%as compared with same grade of OPC mixes.展开更多
基金Funded by the"863"National High-tech Research and Development Program of China(No.2012AA06A112)
文摘We experimentally studied the interaction between pozzolanic material（fly ash） and dehydrated autoclaved aerated concrete（DAAC）. The DAAC powder was obtained by grinding aerated concrete waste to particles fi ner than 75μm and was then heated to temperatures up to 900 ℃. New cementitious material was prepared by proportioning fly ash and DAAC, named as AF. X-ray diffraction（XRD） was employed to identify the crystalline phases of DAAC before and after rehydration. The hydration process of AF was analyzed by the heat of hydration and non-evaporable water content（Wn）. The experimental results show that the highest reactivity of DAAC can be obtained by calcining the powder at 700 ℃ and the dehydrated products are mainly β-C2 S and CaO. The cumulative heat of hydration and Wn was found to be strongly dependent on the replacement level of fl y ash, increasing the replacement level of fl y ash lowered them in AF. The strength contribution rates on pozzolanic effect of fl y ash in AF are always negative, showing a contrary tendency of that of cement-fl y ash system.
文摘Since last two decades,the Portland Pozzolane Cement(PPC)is extensively used in structural concrete.But,till to date,a few literature is available on bond strength of concrete using PPC mixes.There are many literatures available on bond strength of concrete mixes using Ordinary Portland Cement(OPC).Hence,a comparative study was conducted on bond strength between OPC and PPC mixes.In the present investigation,total 24 samples consisting of M20,M35 and M50 grades of concrete and 16 and 25 mm diameter of TMT bar were tested for 7 and 28 days.The pullout bond test was conducted on each specimen as per IS:2770-1967/1997[1]and the results were observed at 0.25 mm slip at loaded end called as critical bond stress and at maximum bond load called as maximum bond stress.It was observed that the critical bond strength of PPC mixes is 10%higher than OPC mixes.Whereas,marginal improvement was noticed in maximum bond strength of PPC mixes.Hence,based on these findings,it could be concluded that development length for PPC mixes could be reduced by 10%as compared with same grade of OPC mixes.
