ABSTRACT Development of Artificial Lightweight Aggregates using Industrial By-products and Its Application to Lightweight Aggregates Concrete Shin, Jae-Kyung Department of Architectural Engineering Graduate School, Cheongju University Directed by Associate Professor Han, Min Cheol The present study ...
ABSTRACT Development of Artificial Lightweight Aggregates using Industrial By-products and Its Application to Lightweight Aggregates Concrete Shin, Jae-Kyung Department of Architectural Engineering Graduate School, Cheongju University Directed by Associate Professor Han, Min Cheol The present study was aimed to develop the artificial light weight aggregate by using bottom ash and wasted stone sludge produced during ground aggregate process for practical use in the building materials. And optimal mixture proportion of readymixed concrete using light weight aggregate was drawn to expand the use and application of light weight aggregate for concrete. In addition, mechanical properties and durability of concrete used light weight aggregate with the change of mix proportion such as S/a and W/B which are respectively separated by designed strength were carefully examined. the following conclusions may be drawn from the obtained data. In the regard to manufacturing lightweight aggregates, it was found that density of lightweight aggregates increased whereas absorption decreased as increase SB ratio and as increase the burning temperature. For high quality of lightweight aggregates, chemical composition ratio should be in the range of SiO2 51~56 %, Al2O3 18~20 %, Fe2O3 5~8 %, CaO 3.0~3.5 %, K2O 2.0~3.5 %, Na2O 2~3 %. And also it was thought that percentage of moisture content of lightweight aggregates should be controlled under 2 % because if it is over 3 %, lightweight aggregates may be spalling. As to kind of flux and additional contents, thermosetting occurred on the surface of lightweight aggregates in as following temperature respectively, Na2CO3 : 850 ℃, Na2SO4 : 1,100 ℃, CaCO3 : 1,200 ℃, CaSO4 : 1,150 ℃ and absorption of lightweight aggregates with NaOH was over 20%, both CaCO3 and Na2CO3 dried density increased, but absorption decreased. In case of NaOH, dried density and absorption were 1.6 g/cm3, 5.8 % respectively in burning condition of 1,150 ℃, but it was considered improper as flux for lightweight aggregates due to the increase of density. And dried density and absorption of lightweight aggregates with glass abrasion sludge were 1.45~1.55 g/cm3, 9~12 % respectively. In the result of forming agent, dried density of lightweight aggregates increased as increase addition of Fe2O3. And in case of BFS, burning temperature for lightweight aggregates was lower than Fe2O3, but it was considered impossible to use a forming agent on account of high density and low absorption. artificial lightweight aggregate with oxidizing slag of 15 % at burning temperature 1,150 ℃ which have low dried density 1.32 g/cm3 and low absorption 7.2 %, can be manufactured. The optimum ratio for manufacturing lightweight aggregates utilized sewage sludge and bottom ash were SB : BA = 8 : 2 then mix Na2SO4 1 %, SS 15 % at burning temperature 1,125 ℃. From the result of the test, it was obtained that passage time from feeding entrance to outlet in a preheating furnace was about 30 minutes in rake angle 1.5 °. In addition, passage time in burning furnace was about 20 minutes in 2.5~3.0 time/min Concrete with developed lightweight aggregates appeared big slump loss, a little high air contents about 1~2 % and also low compressive strength compare to ordinary concrete. In addition, apparent density of concrete with lightweight aggregates was reduced about 400 kg/㎥ compare to ordinary concrete. If lightweight aggregates has single size-distribution, S/a must be adjusted in high about 2~4 % whereas, if it has continuous size-distribution, S/a will be most similar compare to ordinary concrete with ground gravel. the unit volume mass appeared low as follows CG, CLG, SLG, but there were no effect of the unit water and a change of S/a on it. In a bond performance between lightweight aggregates concrete and reinforcing bar, the maximum bond performance of concrete with lightweight aggregates indicated a little low value and the slip indicated shortly at the moment of maximum bond performance in comparison with ordinary concrete. Therefore, it was thought that concrete with lightweight aggregates may be available through the review for anchorage length when drawing structural design. In regard to durability of concrete with lightweight aggregates, length change caused dry shrinkage was the minimum when used LG properly. SLG which has single-size distribution and low absorption indicated that shrinkage was lower than CG in early age, but it has the biggest shrinkage in last age. In the result of resistance of freezing and thawing, all concrete specimen with lightweight aggregates in W/B 60 % indicated under 90 % on account of pop-out phenomenon and in case of CLG, it was reduced to 80 %. In the result of accelerated neutralization, neutralization depth of concrete with lightweight aggregates was bigger than ordinary concrete, but after 8 weeks, it was similar. Chloride Ion Diffusion Coefficient was also not much in it. In the result of evaluation of applying practice for lightweight aggregates concrete, where applying a PPC girder bridge, typical bending failure phenomenon during static loading test occurred. And there has good resistance for fatigue and occurred 3mm of residual strain in PPC bridge system. As a result, performance of a PPC girder and bridge system with lightweight aggregates were demonstrated about 80% comparing to ordinary them. In the result of practical application, slump and air contents of concrete with lightweight aggregates were satisfied with objectives. And even though there were phenomenon that a little aggregate rose slightly up, it can be managed by surface finishing. In summary of this study, eco-friendly and high qualitative lightweight aggregates consisted SB : BA = 8 : 2 and with Na2SO4 1 %, SS 15 %, sewage sludge 10%, dried density 1.32 g/cm3, absorption 7.2 %, can be manufactured. And through the design of mix proportion for lightwe
ABSTRACT Development of Artificial Lightweight Aggregates using Industrial By-products and Its Application to Lightweight Aggregates Concrete Shin, Jae-Kyung Department of Architectural Engineering Graduate School, Cheongju University Directed by Associate Professor Han, Min Cheol The present study was aimed to develop the artificial light weight aggregate by using bottom ash and wasted stone sludge produced during ground aggregate process for practical use in the building materials. And optimal mixture proportion of readymixed concrete using light weight aggregate was drawn to expand the use and application of light weight aggregate for concrete. In addition, mechanical properties and durability of concrete used light weight aggregate with the change of mix proportion such as S/a and W/B which are respectively separated by designed strength were carefully examined. the following conclusions may be drawn from the obtained data. In the regard to manufacturing lightweight aggregates, it was found that density of lightweight aggregates increased whereas absorption decreased as increase SB ratio and as increase the burning temperature. For high quality of lightweight aggregates, chemical composition ratio should be in the range of SiO2 51~56 %, Al2O3 18~20 %, Fe2O3 5~8 %, CaO 3.0~3.5 %, K2O 2.0~3.5 %, Na2O 2~3 %. And also it was thought that percentage of moisture content of lightweight aggregates should be controlled under 2 % because if it is over 3 %, lightweight aggregates may be spalling. As to kind of flux and additional contents, thermosetting occurred on the surface of lightweight aggregates in as following temperature respectively, Na2CO3 : 850 ℃, Na2SO4 : 1,100 ℃, CaCO3 : 1,200 ℃, CaSO4 : 1,150 ℃ and absorption of lightweight aggregates with NaOH was over 20%, both CaCO3 and Na2CO3 dried density increased, but absorption decreased. In case of NaOH, dried density and absorption were 1.6 g/cm3, 5.8 % respectively in burning condition of 1,150 ℃, but it was considered improper as flux for lightweight aggregates due to the increase of density. And dried density and absorption of lightweight aggregates with glass abrasion sludge were 1.45~1.55 g/cm3, 9~12 % respectively. In the result of forming agent, dried density of lightweight aggregates increased as increase addition of Fe2O3. And in case of BFS, burning temperature for lightweight aggregates was lower than Fe2O3, but it was considered impossible to use a forming agent on account of high density and low absorption. artificial lightweight aggregate with oxidizing slag of 15 % at burning temperature 1,150 ℃ which have low dried density 1.32 g/cm3 and low absorption 7.2 %, can be manufactured. The optimum ratio for manufacturing lightweight aggregates utilized sewage sludge and bottom ash were SB : BA = 8 : 2 then mix Na2SO4 1 %, SS 15 % at burning temperature 1,125 ℃. From the result of the test, it was obtained that passage time from feeding entrance to outlet in a preheating furnace was about 30 minutes in rake angle 1.5 °. In addition, passage time in burning furnace was about 20 minutes in 2.5~3.0 time/min Concrete with developed lightweight aggregates appeared big slump loss, a little high air contents about 1~2 % and also low compressive strength compare to ordinary concrete. In addition, apparent density of concrete with lightweight aggregates was reduced about 400 kg/㎥ compare to ordinary concrete. If lightweight aggregates has single size-distribution, S/a must be adjusted in high about 2~4 % whereas, if it has continuous size-distribution, S/a will be most similar compare to ordinary concrete with ground gravel. the unit volume mass appeared low as follows CG, CLG, SLG, but there were no effect of the unit water and a change of S/a on it. In a bond performance between lightweight aggregates concrete and reinforcing bar, the maximum bond performance of concrete with lightweight aggregates indicated a little low value and the slip indicated shortly at the moment of maximum bond performance in comparison with ordinary concrete. Therefore, it was thought that concrete with lightweight aggregates may be available through the review for anchorage length when drawing structural design. In regard to durability of concrete with lightweight aggregates, length change caused dry shrinkage was the minimum when used LG properly. SLG which has single-size distribution and low absorption indicated that shrinkage was lower than CG in early age, but it has the biggest shrinkage in last age. In the result of resistance of freezing and thawing, all concrete specimen with lightweight aggregates in W/B 60 % indicated under 90 % on account of pop-out phenomenon and in case of CLG, it was reduced to 80 %. In the result of accelerated neutralization, neutralization depth of concrete with lightweight aggregates was bigger than ordinary concrete, but after 8 weeks, it was similar. Chloride Ion Diffusion Coefficient was also not much in it. In the result of evaluation of applying practice for lightweight aggregates concrete, where applying a PPC girder bridge, typical bending failure phenomenon during static loading test occurred. And there has good resistance for fatigue and occurred 3mm of residual strain in PPC bridge system. As a result, performance of a PPC girder and bridge system with lightweight aggregates were demonstrated about 80% comparing to ordinary them. In the result of practical application, slump and air contents of concrete with lightweight aggregates were satisfied with objectives. And even though there were phenomenon that a little aggregate rose slightly up, it can be managed by surface finishing. In summary of this study, eco-friendly and high qualitative lightweight aggregates consisted SB : BA = 8 : 2 and with Na2SO4 1 %, SS 15 %, sewage sludge 10%, dried density 1.32 g/cm3, absorption 7.2 %, can be manufactured. And through the design of mix proportion for lightwe
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