Underwater 3D concrete printing (UW3DCP) relocates early-age evolution into a saturated, low-effective-stress regime where washout and seam weakening are controlled by the time-dependent mobility of pore water. This study investigates whether the time-dependent fresh-state hydraulic conductivity, K(t), can serve as a practical metric for UW3DCP materials. A framework for UW3DCP is formulated by coupling hydraulic conductivity <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$K(t)$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>K</mi> <mo stretchy="false">(</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> in the fresh state (proxy for transient preferential path formation) with interlayer integrity measured in air-printed and submerged-printed elements, while also examining the influence of aggregate size. Biopolymer admixtures are examined qualitatively at comparable extrusion and buildability conditions. Cellulose ethers (HPMC) cause only short-lived reductions in <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$K(t)$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>K</mi> <mo stretchy="false">(</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation>; their apparent benefits in shape retention are not sufficient to prevent the early development of washout transport paths. In contrast, a Sphingan gum forms a more stable and cohesive gel network that suppress both level and drift of <InlineEquation ID="IEq3"> <EquationSource Format="TEX">$K(t)$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>K</mi> <mo stretchy="false">(</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> within the deposition-to-setting time window. Within the scope of the present permeability test, K(t) discriminates mixture stability and captures the influence of polymer chemistry and granular packing on washout susceptibility. This result therefore supports the use of fresh-state K(t) as a promising acceptance metric for UW3DCP mixture qualification.

Underwater 3D printing of concrete: tailoring mix-design to tackle washout

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2026年5月10日

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Y. Jacquet,
A. Perrot,
V. Picandet

摘要

Underwater 3D concrete printing (UW3DCP) relocates early-age evolution into a saturated, low-effective-stress regime where washout and seam weakening are controlled by the time-dependent mobility of pore water. This study investigates whether the time-dependent fresh-state hydraulic conductivity, K(t), can serve as a practical metric for UW3DCP materials. A framework for UW3DCP is formulated by coupling hydraulic conductivity $K(t)$ $K (t)$ in the fresh state (proxy for transient preferential path formation) with interlayer integrity measured in air-printed and submerged-printed elements, while also examining the influence of aggregate size. Biopolymer admixtures are examined qualitatively at comparable extrusion and buildability conditions. Cellulose ethers (HPMC) cause only short-lived reductions in $K(t)$ $K (t)$ ; their apparent benefits in shape retention are not sufficient to prevent the early development of washout transport paths. In contrast, a Sphingan gum forms a more stable and cohesive gel network that suppress both level and drift of $K(t)$ $K (t)$ within the deposition-to-setting time window. Within the scope of the present permeability test, K(t) discriminates mixture stability and captures the influence of polymer chemistry and granular packing on washout susceptibility. This result therefore supports the use of fresh-state K(t) as a promising acceptance metric for UW3DCP mixture qualification.