Guidelines for mix proportioning of fly ash/GGBS based alkali activated concretes

By Ali Rafeet, R. Vinai, M. Soutsos, Wei Sha. 2017

231 citations recorded by the source corpus.

Abstract The effects of paste volume, water content and precursor blend on consistency, setting time and compressive strength of alkali activated concrete (AAC) produced with fly ash (FA) and ground granulated blast furnace slag (GGBS) have been investigated with the aim of developing a suitable mix design procedure. Paste volumes in the range 30–33% were found not to influence the compressive strength but did influence the consistency of the mixes. The water-to-solid ratio was found to influence compressive strength and setting time. Increasing GGBS content in the binder blend resulted in an increase of the compressive strength, but higher GGBS content caused also early setting which may be undesirable. A mix design procedure has been developed and has been used to determine the constituent mix proportions for three classes of concretes, i.e. (a) a ready-mix concrete with nominal strength 35 MPa, (b) a typical structural concrete with nominal strength 50 MPa, and (c) a high strength concrete for precast applications with nominal strength 70 MPa. Cost analysis was carried out to compare the AAC with Portland cement concretes with similar properties. Normal strength Portland cement concrete (PC), as typically used in ready mix industry has been shown to be less expensive than AAC. However, alkali activated concrete can be competitively priced for high strength concretes. An empirical step-by-step procedure is presented for selecting trial mix proportions for concretes with a range of consistency values, setting times and cube compressive strengths.

Subfields: Civil and Structural Engineering, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/56dda4d351f7d478953d46b2e1d6e71e52c288de

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In Civil and Structural Engineering

1. Mingzhong Zhang
2. G. Fang
3. W. K. Ho
4. W. Tu

In Materials Chemistry

1. G. Fang
2. Mingzhong Zhang
3. W. Tu

Citations in the corpus

• Workability and mechanical properties of alkali-activated fly ash-slag concrete cured at ambient temperature (2018, background): “According to previous research, the alkaline activation process of AAFS would be accelerated with the decrease of AL/B ratio due to the decrease of consistency of mixtures [49].”
• Production of sodium silicate powder from waste glass cullet for alkali activation of alternative binders (2019, unknown): “Mix proportions for three concretes of 28-day mean compressive strengths of 35, 50 and 70 MPa, described in [62], were used for estimating the costs per cubic metre when (a) commercially available activators and (b) powder activators were used.”
• Use of Vietnamese rice husk ash for the production of sodium silicate as the activator for alkali-activated binders (2018, unknown): “Since the alkali activators represent about 40% of the cost of alkali activated concrete (Rafeet et al., 2017), the use of RHA-derived waterglass would lead to savings of about 22% on the cost per cubic metre of alkali activated concrete.”