3D-Printable Concrete Using Stabilized Soil (2026-04)¶

Stabilized soils are sensitive to moisture content, and their performance is significantly influenced by the stabilizer (i.e. binder) and prevailing humidity. To understand their suitability as fine aggregate in 3D printed concrete, this study investigates the effects of binders and curing regimes. Two binder systems, ordinary Portland cement (C) and blended cement with 15% fly ash and 15% GGBS (F15G15), were evaluated under three curing regimes: ambient curing (AC), burlap plus sealed curing (BSC), and water curing (WC). The fine aggregates comprised equal proportions of sand and natural soil, maintaining a filler-to-binder ratio of 2.0. Investigations were conducted on the compressive strength, bond strength, porosity, sorptivity, shrinkage, and microstructure, while printability was assessed through flowability, extrudability, and buildability. Results showed that mix F15G15 exhibited superior flow retention with only 5.9% slump loss over 20 min compared to 9.1% for mix C. Both mixes demonstrated superior extrudability and buildability up to a height of 300 mm or more. The inherent anisotropy in printed specimens resulted in varied effects on compressive strength. Compared to mix C, F15G15 resulted in changes of − 44 to + 17% when tested along and across the printing directions, respectively. Compared to AC, WC improved strength by up to 148%, and reduced porosity and sorptivity by up to 55% and 88%, respectively. Furthermore, both mixes exhibited reduced shrinkage values under WC (95–158 μm) and BSC (54–84 μm) compared to AC (470–560 μm) at 55 days.