Abstract
Alkali-activated fly ash-slag (AAFS) concrete is a new blended alkali-activated concrete that has been increasingly studied over the past decades because of its environmental benefits and superior engineering properties. However, there is still a lack of comprehensive studies on the effect of different factors on the fresh and hardened properties of AAFS concrete. This paper aims to provide a thorough understanding of workability and mechanical properties of AAFS concrete cured at ambient temperature and to obtain the optimal mixtures for engineering application. A series of experiments were carried out to measure workability, setting time, compressive strength, splitting tensile strength, flexural strength and dynamic elastic modulus of AAFS concrete. The results showed that workability and setting time decreased with the increase of slag content and molarity of sodium hydroxide solution (SH). Compressive strength increased with the increase of slag content and molarity of SH as well as the decrease of alkaline activator to binder (AL/B) ratio, but it did not have significant relationship with sodium silicate to sodium hydroxide (SS/SH) ratio. In addition, equations provided by ACI code, Eurocode and previous researchers for ordinary Portland cement concrete overestimated the values of splitting tensile strength, flexural strength and dynamic elastic modulus of AAFS concrete. The optimal mixtures of AAFS concrete were set as slag content of 20–30%, AL/B ratio of 0.4, 10 M of SH, and SS/SH ratio of 1.5–2.5 considering the performance criteria of workability, setting time and compressive strength.
Highlights
Alkali-activated materials (AAM) is an inorganic binder derived by the reaction of an alkali metal source with a⇑ Corresponding author.solid silicate powder such as fly ash (FA) and slag [1]
The main purpose of this study is to provide a thorough understanding of workability, setting time and mechanical properties of activated fly ash-slag (AAFS) concrete cured at ambient temperature
activated concrete (AAC) with the slump values in the range of 50 mm and 89 mm is classified as medium workability, while AAC with slump values below 50 mm is considered as low workability due to the significant vibration of compaction
Summary
Alkali-activated materials (AAM) is an inorganic binder derived by the reaction of an alkali metal source (solid or dissolved) with a. Solid silicate powder such as fly ash (FA) and slag [1]. AAM has been recognized as a promising alternative binder to ordinary Portland cement (OPC) because of its environmental benefits and superior engineering properties [2,3,4,5]. The manufacture of OPC is known as a significant contributor to greenhouse gas emissions accounting for around 5% of global CO2 emissions [6,7].
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