A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
EFFECT OF GYPSUM POWDER AS PARTIAL REPLACEMENT OF EAST CEMENT ON FRESH AND HARDENED PROPERTIES OF SELF-COMPACTING CONCRETE
Self-compacting concrete (SCC) is among the latest advancements in concrete technology. SCC has got its flow-ability and compact-ability properties by the use of a high amount of cement and fine aggregate as compared to normal concrete. The use of a high amount of cement increases the cost of self-compacting concrete. To reduce the cost of cement and to gain the subsequent improvement of properties, replacing it partially with other cementitious or non- cementitious materials is taken as one solution. Many types of research have been done on the replacement of cement with limestone, silica fume, phosphogypsum, etc. Gypsum is naturally abundant in Ethiopia. Only in Muger and Jema Valleys, more than 57,000,000 tons reserve of gypsum is available. Even though it is not quantified, comparable or more deposit is available in Abay gorge, Mekele outlier, and other locations. Using this abundant material as a replacement of cement will reduce the cost of self-compacting concrete and play a huge role in the reduction of carbon dioxide emissions to the environment. In this study, the potential of gypsum powder as a replacement of cement and its effect on the fresh and hardened properties of SCC with different percentage replacement is investigated. The aim of the study is to determine the optimum amount of gypsum powder replacement for the desired compactability, flowability, viscosity and strength properties in addition to spotting the effect of increment of gypsum powder as 0%, 5%, 10%, 15%, and 20% along with its economic viability. SCC mixes with gypsum powder replacement were prepared with the ACI mix design method for SCC. Cement grade CEM I 42.5N, coarse aggregates less than 12.5mm size, river sand, and Sikament® NN superplasticizer were used. Slump flow, L-box, V-funnel and setting time tests were conducted for fresh SCC properties while compressive tests were done for hardened concrete properties with ASTM testing procedures. A total of 36 cube samples was prepared for tests at 7, 14 and 28 days. Among the replacements, 20% replacement did not satisfy the fresh SCC properties and was not considered for strength comparison. 15% replacement was found as an optimum replacement percentage. Compressive strength at twenty-eight days of 5%, 10% and 15% replacements attained respectively 72.18%, 58.12% and 60.56% strength of the control (0%) 40MPa SCC. Gypsum powder replaced cement showed accelerated setting times. Only 5% of replacement cement maintained the Portland cement setting time limits. Initial setting time is highly improved to more than 5hrs for all replacements with the addition of superplasticizer. Hence, gypsum powder can be used as a cement replacement for the production of SCC with reduced compressive strength.
EFFECT OF GYPSUM POWDER AS PARTIAL REPLACEMENT OF EAST CEMENT ON FRESH AND HARDENED PROPERTIES OF SELF-COMPACTING CONCRETE
Self-compacting concrete (SCC) is among the latest advancements in concrete technology. SCC has got its flow-ability and compact-ability properties by the use of a high amount of cement and fine aggregate as compared to normal concrete. The use of a high amount of cement increases the cost of self-compacting concrete. To reduce the cost of cement and to gain the subsequent improvement of properties, replacing it partially with other cementitious or non- cementitious materials is taken as one solution. Many types of research have been done on the replacement of cement with limestone, silica fume, phosphogypsum, etc. Gypsum is naturally abundant in Ethiopia. Only in Muger and Jema Valleys, more than 57,000,000 tons reserve of gypsum is available. Even though it is not quantified, comparable or more deposit is available in Abay gorge, Mekele outlier, and other locations. Using this abundant material as a replacement of cement will reduce the cost of self-compacting concrete and play a huge role in the reduction of carbon dioxide emissions to the environment. In this study, the potential of gypsum powder as a replacement of cement and its effect on the fresh and hardened properties of SCC with different percentage replacement is investigated. The aim of the study is to determine the optimum amount of gypsum powder replacement for the desired compactability, flowability, viscosity and strength properties in addition to spotting the effect of increment of gypsum powder as 0%, 5%, 10%, 15%, and 20% along with its economic viability. SCC mixes with gypsum powder replacement were prepared with the ACI mix design method for SCC. Cement grade CEM I 42.5N, coarse aggregates less than 12.5mm size, river sand, and Sikament® NN superplasticizer were used. Slump flow, L-box, V-funnel and setting time tests were conducted for fresh SCC properties while compressive tests were done for hardened concrete properties with ASTM testing procedures. A total of 36 cube samples was prepared for tests at 7, 14 and 28 days. Among the replacements, 20% replacement did not satisfy the fresh SCC properties and was not considered for strength comparison. 15% replacement was found as an optimum replacement percentage. Compressive strength at twenty-eight days of 5%, 10% and 15% replacements attained respectively 72.18%, 58.12% and 60.56% strength of the control (0%) 40MPa SCC. Gypsum powder replaced cement showed accelerated setting times. Only 5% of replacement cement maintained the Portland cement setting time limits. Initial setting time is highly improved to more than 5hrs for all replacements with the addition of superplasticizer. Hence, gypsum powder can be used as a cement replacement for the production of SCC with reduced compressive strength.
EFFECT OF GYPSUM POWDER AS PARTIAL REPLACEMENT OF EAST CEMENT ON FRESH AND HARDENED PROPERTIES OF SELF-COMPACTING CONCRETE
CHERNET GETANEH TEBABAL (author)
2019-10-28
doi:10.20372/nadre/4129
Theses
Electronic Resource
English
DDC:
690
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