Alkali-activated concrete (AAC) has emerged as a sustainable alternative to conventional concrete due to its lower carbon emissions and effective use of industrial by-products. Several studies have explored the performance of AAC in both fresh and hardened states. However, the broader application of these mixes in real-time applications can be enhanced through further modifications to meet current needs. Fiber-reinforced self-compacting alkali-activated concrete (FSAAC) mixes represent one such class of innovative concrete mixes. This study evaluates the fresh-state, mechanical, and fracture properties of FSAAC mixes optimized using Taguchi’s design of experiments (DOE) methodology. An L9 orthogonal array was employed with three variables at three levels: fly ash (FA) content (30%, 40%, 50%) as partial replacement of blast furnace slag, steel fiber (SF) content (0.25%, 0.5%, 0.75% by concrete volume), and fiber aspect ratio (AR) (40, 60, 80). A control mix without FA and SF was included in the comparison study. All FSAAC mixes satisfied EFNARC guidelines for fresh-state properties. Fracture parameters were determined through three-point bending (TPB) tests. The F30-S0.75-A80 mix exhibited superior performance with compressive strength of 66.33 MPa, flexural strength of 7.05 MPa, initial fracture toughness <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41024_2025_620_Article_IEq1.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="40" /> </InlineMediaObject> <EquationSource Format="TEX">$({\text{K}}_{\text{IC}}^{\text{ini}})$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">(</mo> <msubsup> <mtext>K</mtext> <mrow> <mtext>IC</mtext> </mrow> <mtext>ini</mtext> </msubsup> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> of 0.813 MPa√m, unstable fracture toughness <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41024_2025_620_Article_IEq2.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="38" /> </InlineMediaObject> <EquationSource Format="TEX">${\text{(K}}_{\text{IC}}^{\text{uns}}$</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mtext>(K</mtext> <mrow> <mtext>IC</mtext> </mrow> <mtext>uns</mtext> </msubsup> </math></EquationSource> </InlineEquation>) of 6.123 MPa√m, fracture energy (GF) of 5513.80 N/m, and a toughness ratio of 0.133. Compared to the control mix, the mix F30-S0.75-A80 showed 22.6%, 14.35%, 313.15% and 2518% rise in flexural strength, <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41024_2025_620_Article_IEq3.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="27" /> </InlineMediaObject> <EquationSource Format="TEX">${\text{K}}_{\text{IC}}^{\text{ini}}$</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mtext>K</mtext> <mrow> <mtext>IC</mtext> </mrow> <mtext>ini</mtext> </msubsup> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41024_2025_620_Article_IEq4.gif" Format="GIF" Height="18" Rendition="HTML" Resolution="72" Type="Linedraw" Width="32" /> </InlineMediaObject> <EquationSource Format="TEX">${\text{K}}_{\text{IC}}^{\text{uns}}$</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mtext>K</mtext> <mrow> <mtext>IC</mtext> </mrow> <mtext>uns</mtext> </msubsup> </math></EquationSource> </InlineEquation> and GF, respectively. Taguchi analysis identified optimal mix proportions for slump flow at FA 50%, SF 0.25%, AR 40, and for <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41024_2025_620_Article_IEq3.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="27" /> </InlineMediaObject> <EquationSource Format="TEX">${\text{K}}_{\text{IC}}^{\text{ini}}$</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mtext>K</mtext> <mrow> <mtext>IC</mtext> </mrow> <mtext>ini</mtext> </msubsup> </math></EquationSource> </InlineEquation> at FA 30%, SF 0.75%, AR 60. For other properties, proportions were optimized at FA 30%, SF 0.75%, AR 80. Regression models developed exhibited high degree of predictive accuracy, closely aligning with experimental outcomes.

Performance evaluation of fiber reinforced self compacting alkali activated concrete mixes—a DoE approach

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发表日期：

2025年5月4日

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Gundupalli Bhanu Prakash,
M. H. Prashanth,
Mattur C. Narasimhan,
Kaku Mahendra,
Amit Kumar Das

摘要

Alkali-activated concrete (AAC) has emerged as a sustainable alternative to conventional concrete due to its lower carbon emissions and effective use of industrial by-products. Several studies have explored the performance of AAC in both fresh and hardened states. However, the broader application of these mixes in real-time applications can be enhanced through further modifications to meet current needs. Fiber-reinforced self-compacting alkali-activated concrete (FSAAC) mixes represent one such class of innovative concrete mixes. This study evaluates the fresh-state, mechanical, and fracture properties of FSAAC mixes optimized using Taguchi’s design of experiments (DOE) methodology. An L9 orthogonal array was employed with three variables at three levels: fly ash (FA) content (30%, 40%, 50%) as partial replacement of blast furnace slag, steel fiber (SF) content (0.25%, 0.5%, 0.75% by concrete volume), and fiber aspect ratio (AR) (40, 60, 80). A control mix without FA and SF was included in the comparison study. All FSAAC mixes satisfied EFNARC guidelines for fresh-state properties. Fracture parameters were determined through three-point bending (TPB) tests. The F30-S0.75-A80 mix exhibited superior performance with compressive strength of 66.33 MPa, flexural strength of 7.05 MPa, initial fracture toughness $({\text{K}}_{\text{IC}}^{\text{ini}})$ $(K_{IC}^{ini})$ of 0.813 MPa√m, unstable fracture toughness ${\text{(K}}_{\text{IC}}^{\text{uns}}$ ${(K}_{IC}^{uns}$ ) of 6.123 MPa√m, fracture energy (G_F) of 5513.80 N/m, and a toughness ratio of 0.133. Compared to the control mix, the mix F30-S0.75-A80 showed 22.6%, 14.35%, 313.15% and 2518% rise in flexural strength, ${\text{K}}_{\text{IC}}^{\text{ini}}$ $K_{IC}^{ini}$ , ${\text{K}}_{\text{IC}}^{\text{uns}}$ $K_{IC}^{uns}$ and G_F, respectively. Taguchi analysis identified optimal mix proportions for slump flow at FA 50%, SF 0.25%, AR 40, and for ${\text{K}}_{\text{IC}}^{\text{ini}}$ $K_{IC}^{ini}$ at FA 30%, SF 0.75%, AR 60. For other properties, proportions were optimized at FA 30%, SF 0.75%, AR 80. Regression models developed exhibited high degree of predictive accuracy, closely aligning with experimental outcomes.