Abstract
In the last decade, the use of Fly ash as replacement to improve the strength and performance of the cement has become a part of mortar and concrete manufacturing. When the used amount of fly ash ranges from 20 to 25%, the proprieties of concrete and mortars such as strength and durability are improved, which also reduce the Portland cement consumption and its impact on environment. For some special applications the High-Volume Fly Ash (HVFA) (up to 50%) is recommended, but the use of HVFA is still limited because of the low early age strength. The aim of this study is to overcome the constraints caused by the use of the High-Volume Fly Ash, by upgrading the mortar using grinding to reduce the particle size, and by the application of an upsetting force to modify the behavior of swelling and to modify the crystal structure of ettringite in order to increase the early age strength of the mortar. The results show an increase in the rupture resistance at 7 days and 28 days by 60% and 30% respectively. Which will make the use of HVFA mortar possible in construction industry and therefore reduce more CO2 emissions from the cement production. Doi: 10.28991/cej-2021-03091731 Full Text: PDF
Highlights
The concrete and mortar are a widely used in construction industry due to its high strength and its durability
The results show that the use of Fly ash particles of 100 μm instead of 500 μm decreases the water requirement and improves the strength of the mortar
Studies and recent experimental studies shows, that the rate of strength development depends upon the following factors: Fly ash characteristics such as its chemical and mineralogical composition, fineness, and pozzolanic reactivity, Type of cement, Replacement level of cement with fly ash, Mixture proportions, Ambient temperature, Curing environment reference. It is the pore structure of the cement matrix that determines its porosity and permeability and its sensitivity to transport and diffusion processes, the High Volume Fly Ash (HVFA) as replacement of cement reduces the bleeding and segregation, which reduces the water demand
Summary
The concrete and mortar are a widely used in construction industry due to its high strength and its durability. Due to several factors, such as the higher consistency during the fresh stage, the superior durability with respect to chloride resistance and the lower material cost, the Fly ash is widely used in construction industry. The use of high volume Fly ash concrete (HVFA) decreases more the CO2 emission, by reducing the amount of the Portland cement [4]. The HVFA gives better results compared to Portland cement, where the strength resistance at late age as well as the resistance to chloride ion penetration are improved; the permeability and the shrinkage are reduced, which make the mortar and concrete have better durability characteristics [4]
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