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- Author or Editor: Shirish V. Deo x
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Abstract
High performance concrete is extensively used for construction works in recent era. For the preparation of high performance concrete (HPC) mineral and chemical admixtures are used. The addition of mineral admixtures minimizes the utilization of cement and makes concrete more sustainable. The addition of metakaolin as a substitute to cement enhances the properties of concrete. There is need to study the mechanical and micro-structural properties of concrete containing metakaolin as cementitious material. In this work an endeavour has been made to study the properties of HPC employing matakaolin as an alternative for cement. The cement has been replaced with metakaolin by 5%, 10%, 15%, 20%, and 25% respectively for 0.25, 0.3, and 0.35 w/c ratios. The strength and electrical resistivity tests are conducted for all concrete mixes on triplicate. Results confirm that the accumulation of metakaolin increases the properties of HPC. A maximum of 49% increase in compressive strength in concrete was observed by the accumulation of 15% of metakaolin in concrete as substitute to cement for 0.25 w/c ratio in comparison to standard concrete. The development of secondary calcium silicate hydrates and minimal Ca(OH)2 components was revealed by X-ray spectroscopy, indicating that the concrete was denser. The results of this study revealed that metakaolin has a considerable impact on high-performance concrete, particularly in terms of compressive and flexural strength.
Abstract
Alkali Activated Concrete (AAC) is a moderately new form of concrete that has gotten a lot of interest in recent decades owing to its environmental advantages and features. However, further research into the effects of various proportions of fly ash, ground granulated blast furnace slag (GGBS), and lime on the characteristics of calcium-based AAC is still needed. This work aims to provide detailed information about the characteristics of AAC with various concentrations of fly ash, GGBS, and lime in order to produce the best combinations for engineering applications. The alkali activators in this investigation are sodium hydroxide and calcium silicate. All concrete mixes are examined for workability, strength, and durability for knowing the impact of fly ash, GGBS, and lime on AAC performance. The results specify that the increase in dosage of GGBBS diminishes the workability. The accumulation of only lime and GGBS shows optimum strength and durability results. In this study further regression analysis has been carried out for predicting the strength of the AAC. The regression equation was developed using the response surface approach for reliably predicting experimental outcomes with an acceptable margin of error.
Abstract
The manufacturing of cement liberates the green-house gasses into atmosphere. To overcome this problem so many alternative materials has been invented by researchers to minimize addition of cement. The incorporation of these alternative materials as cementitious material in concrete enhances the attributes of concrete. In this scenario metakaolin gained momentum as a substitution to cement in concrete. Most of the researchers studied the performance of concrete incorporating metakaolin as cementitious material in normal curing conditions. There is a need for analysing the impact of accelerated curing on properties of concrete by incorporating metakaolin as cementitious material. The current construction industry needs high early strength for removal of form work in early ages. The accelerated curing is a method which provides high early strength. In this study, different proportions of metakaolin are added as partial alternative to cement and cured in accelerated curing tank for 3.5 h. The strength parameters test, durability test, and micro-structural parameter tests are performed on these samples. Further, micro-structural analysis has been carried out using SEM, and EDX tests. Results depicted the incorporation of 15% of metakaolin as substitute to cement amplifies the overall performance of concrete in accelerated curing regime.
