The properties of the self-compacting concrete mix depend on an automatic introduction of air bubbles caught during the process of mixing. What is interesting, the criterion for self-compactibility is not taken into c...The properties of the self-compacting concrete mix depend on an automatic introduction of air bubbles caught during the process of mixing. What is interesting, the criterion for self-compactibility is not taken into consideration in commonly used self-compacting tests. On the basis of different tests concerning self-compacting concrete mixes, it has been found out that too high air content in their volume was the result of superplasticizer, in spite of meeting the self-compactibility criteria （i.e., self-venting）. For the decrease of too high air volume in SCC, the use of anti-foaming admixture （AFA） is proposed. As a result, the effect of AFA mix flow diameter is increased and the flow time is decreased. Moreover, the workability loss is lower. In case of mix incorporating AFA, their high flowability does not cause segregation of the mix, what is possible in case of SCC incorporating only superplasticizer. However, the time of the introduction of AFA and its type is essential to get higher flowability degree, but it is not important to achieve low air volume in SCC.展开更多
Self-compacting concrete （SCC） is defined so that no vibration is necessary for the compaction. The main criteria of producing SCC have to satisfy the following characteristics [1, 2, 3]： （1） Ability to flow into...Self-compacting concrete （SCC） is defined so that no vibration is necessary for the compaction. The main criteria of producing SCC have to satisfy the following characteristics [1, 2, 3]： （1） Ability to flow into and completely fill complex forms under its own weight; （2） Ability to pass through and bond to congested reinforcements; （3） High resistance to aggregate segregation. Self-compacting concrete presents a significant sign in improving the product quality and efficiency of the building industry. It also enhances the working conditions and the quality and appearance of concrete. Japan has been used self-compacting concrete in bridge, building and tunnel construction since the early 1990s. In the last decade, SCC has been produced a high potential for greater acceptance and wider applications in highway bridge construction in the Europe and U.S.. However, till now, there is no application of SCC in the construction industry in Egypt. Therefore, the main objective of this research is to produce SCC by using the locally available materials in our region such as basalt, gravel, sand, limestone powder and silica fume. Experimental programme was designed to characterize the properties of fresh and hardened SCC. It comprises different concrete mixes thbricated with different types and percentages of constituent materials. Three full-scale reinforced concrete beams were fabricated from the SCC mixes and tested under flexure. For the purpose of comparison, an extra RC beam was made of conventional normal concrete to serve as a reference beam. This study, in general, demonstrated that the applications of SCC in construction industry oiler products with enhanced characteristics as well as could be economical.展开更多
文摘The properties of the self-compacting concrete mix depend on an automatic introduction of air bubbles caught during the process of mixing. What is interesting, the criterion for self-compactibility is not taken into consideration in commonly used self-compacting tests. On the basis of different tests concerning self-compacting concrete mixes, it has been found out that too high air content in their volume was the result of superplasticizer, in spite of meeting the self-compactibility criteria （i.e., self-venting）. For the decrease of too high air volume in SCC, the use of anti-foaming admixture （AFA） is proposed. As a result, the effect of AFA mix flow diameter is increased and the flow time is decreased. Moreover, the workability loss is lower. In case of mix incorporating AFA, their high flowability does not cause segregation of the mix, what is possible in case of SCC incorporating only superplasticizer. However, the time of the introduction of AFA and its type is essential to get higher flowability degree, but it is not important to achieve low air volume in SCC.
文摘Self-compacting concrete （SCC） is defined so that no vibration is necessary for the compaction. The main criteria of producing SCC have to satisfy the following characteristics [1, 2, 3]： （1） Ability to flow into and completely fill complex forms under its own weight; （2） Ability to pass through and bond to congested reinforcements; （3） High resistance to aggregate segregation. Self-compacting concrete presents a significant sign in improving the product quality and efficiency of the building industry. It also enhances the working conditions and the quality and appearance of concrete. Japan has been used self-compacting concrete in bridge, building and tunnel construction since the early 1990s. In the last decade, SCC has been produced a high potential for greater acceptance and wider applications in highway bridge construction in the Europe and U.S.. However, till now, there is no application of SCC in the construction industry in Egypt. Therefore, the main objective of this research is to produce SCC by using the locally available materials in our region such as basalt, gravel, sand, limestone powder and silica fume. Experimental programme was designed to characterize the properties of fresh and hardened SCC. It comprises different concrete mixes thbricated with different types and percentages of constituent materials. Three full-scale reinforced concrete beams were fabricated from the SCC mixes and tested under flexure. For the purpose of comparison, an extra RC beam was made of conventional normal concrete to serve as a reference beam. This study, in general, demonstrated that the applications of SCC in construction industry oiler products with enhanced characteristics as well as could be economical.
