Study on the setting and flow characteristics, unconfined compressive strength, and microscopic properties of ground polymer grouting materials in a recycled concrete micropowder system

Abstract

This study innovatively develops high-strength geopolymers for grouting materials with a high recycled concrete powder (RCP) usage of 60% to meet engineering needs. It investigates the impact of slurry synthesis parameters such as the mass ratio of RCP to granulated blast-furnace slag (r_RP/GS), water glass modulus (M_s), alkali equivalent (r_AE), and the ratio of water mass to solids mass (r_L/S) on the properties of high-performance geopolymer grouting materials (HRCP-GP). The results reveal the optimal parameter intervals: r_RP/GS = 60:40, M_s = 1.2 – 1.4, r_AE = 7% – 9%, and r_L/S = 0.38 – 0.40. Under these conditions, especially when w(RCP) is 60%, M_s = 1.4, r_AE = 9%, and r_L/S = 0.40, the 28 d compressive strength of the slurry reaches 45.81 MPa, ensuring excellent solidification flow properties. Microscopic analyses show that at the optimum alkali excitation ratio, the inert crystallites in RCP are efficiently solubilized and polymerized to form a dense three-dimensional network structure coexisting with C-(N)-A-S–H and C-(A)-S–H gels. This study provides a new approach for the development and application of sustainable grouting materials.

Keywords

Recycled concrete powder / Geopolymer / Grouting material / Engineering performance / Micro mechanisms

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Funding

Supported by Sichuan Science and Technology Program(2025YFHZ0321)

Hainan Province “Nanhai New Star”project funding(202309008)

Hainan Provincial Natural Science Foundation of China(522CXTD510)

Academician Innovation Platform Project of Hainan Province(YSPTZX202320)

RIGHTS & PERMISSIONS

The Author(s)