Ternary Blends of White Cement, Limestone, and Waste Glass for 3D Printing

Abstract

<jats:title>Abstract</jats:title> <jats:p> This work focuses on the development of white formulations for 3DPC, a characteristic rarely addressed in the literature but relevant for architectural applications. The 3DPC was developed based on an integrative design to reach carbon-efficient white ternary blends for 3DPCC, reflecting engineering and environmental balance. A central composite design (CCD) was followed to identify statistical models capable of describing key properties of ternary blends at the paste level. Response models were fitted for flowability, setting time, electrical resistivity, mechanical strength, and global warming potential (GWP) as functions key mixture design ratios, including water-to-powder ratio ( <jats:inline-formula> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper V w divided by upper V p" display="inline" overflow="scroll"> <mml:mi>V</mml:mi> <mml:mi>w</mml:mi> <mml:mo stretchy="false">/</mml:mo> <mml:mi>V</mml:mi> <mml:mi>p</mml:mi> </mml:math> </jats:inline-formula> ), water-to-cement ratio (w/c), superplasticizer-to-powder ratio (Sp/p), and waste glass powder-to-cement ratio (GP/c). Several potential blends were obtained, and w/c and GP/c were the most significant variables in the output properties evaluated. Conversely, the superplasticizer showed the most significant impact on the fresh-state properties and initial setting time. A numerical optimization technique based on the desirability function was applied to the derived models to determine potential ternary binders for the mortar study. One of the optimal ternary blends was fixed and the aggregate was introduced, and additional tests were performed to adjust the initial slump and open time. The optimal mortar presents a cement-tosupplementary cementitious materials (SCM) mass ratio of <jats:inline-formula> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="1 ratio 1" display="inline" overflow="scroll"> <mml:mn>1</mml:mn> <mml:mo></mml:mo> <mml:mn>1</mml:mn> </mml:math> </jats:inline-formula> , an initial slump of 190 mm, an open time of at least 1 h, a compressive strength of 58 MPa, and GWP of <jats:inline-formula> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="377 k g upper C upper O 2 e q divided by normal m cubed" display="inline" overflow="scroll"> <mml:mn>377</mml:mn> <mml:mtext></mml:mtext> <mml:msub> <mml:mrow> <mml:mi>kgCO</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> <mml:mi>eq</mml:mi> <mml:mo stretchy="false">/</mml:mo> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">m</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> </mml:msup> </mml:math> </jats:inline-formula> . To end the investigation, the mortar was printed. Notably, the incorporation of glass powder did not compromise the light color of the material, highlighting its chromatic stability. Furthermore, the white base enabled controlled addition of pigments, expanding the range of color customization according to architectural design requirements. </jats:p>