Abstract
Cement is one of the main constituents of concrete material and it is one of the main sources of carbon dioxide emissions in the environment. Fillers within a range of 5–7% from different sources can be used as a replacement of cement without compromising the properties of concrete or even tailoring for required property. This paper investigates the influence of inactive silica filler and silica fume on the mechanical- and durability-related properties of concrete with different strengths. The investigated mechanical properties focused on compressive strength at different ages up to 400 days, while the durability-related properties focused on porosity and rapid chloride ion penetrability (RCPT). Two types of ultrafines, namely quartz ultrafine and silica fume, were used. Concrete mixtures with four different water/binder ratios (0.25, 0.30, 0.35, 0.40) were prepared for various dosages of quartz ultrafine (0%, 5%, 8%, 10%, 15%, 25%, and 35%) and different dosages of silica fume (0%, 8%, 10%, and 12%). The results revealed that the compressive strength and durability related properties of concrete with different dosages of ultrafines and silica fume were significantly affected; however, there was a negative impact of ultrafine filler on the compressive strength after replacement of more than 8% of ultrafines. The strength relationships for the concrete with different water-to-cement ratio were assessed and certain modifications were proposed for ultrafines and silica fume. Predictive models were proposed for predicting the compressive strength of concrete in terms of RCPT and porosity for different levels of replacements of ultrafines and silica fume.
Highlights
Concrete is a heterogeneous material composed itself of different materials such as coarse aggregate, fine aggregate, cement, etc
There was a slight increase in the compressive strength with the replacement of 8% of cement with ultrafine
Once the dosage of ultrafine was increased from 10%, a decrease in compressive strength was observed at the age of 28 days
Summary
Concrete is a heterogeneous material composed itself of different materials such as coarse aggregate, fine aggregate, cement, etc. The physical and chemical properties of these materials significantly affect the properties of concrete. One of the most important parts of such materials are fine fillers which compensate for the irregularities of aggregates available in concrete [1]. Fine fillers can be a better alternate for the replacement of cement, and can aid in reducing emissions of carbon dioxide in atmosphere. Higher levels of replacement of cement will reduce emission of CO2 in the environment. Concrete with higher mechanical and durability properties are prepared through dense structure of matrix. Physical densifying through properly grading material in the matrix will prepare more compacted structures [3]. The chemical action (pozzolanic reaction) is explained by fixing of lime release during cement hydration to form a new generation of more compact C–S–H, which
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