3D printing of calcined clay-limestone-based cementitious materials

This paper aims to investigate the influences of high Portland cement substitutions (>60 wt%) by low-grade calcined clay (CC) and limestone (LF) on 3D concrete printability, stiffness evolution and early-age hydration. Results show that, with the same dosage of admixtures (superplasticizer and viscosity modifier), increasing LF and CC...

Improving printability of limestone-calcined clay-based cementitious materials by using viscosity-modifying admixture

In 3D concrete printing (3DCP), it is necessary to meet contradicting rheological requirements: high fluidity during pumping and extrusion, and high stability and viscosity at rest to build the layered structure. In this paper, the impact of the hydroxypropyl methylcellulose (HPMC)-based viscosity-modifying admixture (VMA) on the 3D printability...

Effect of different grade levels of calcined clays on fresh and hardened properties of ternary-blended cementitious materials for 3D printing

This study aims to investigate the influences of different grades of calcined clay on 3D printability, compressive strength (7 days), and hydration of limestone and calcined clay-based cementitious materials. Calcined clays that contained various amounts of metakaolin were achieved by blending low-grade calcined clay (LGCC) and high-grade...

Effect of printing parameters on interlayer bond strength of 3D printed limestone-calcined clay-based cementitious materials: An experimental and numerical study

For a single batch material, time intervals and nozzle standoff distances between two subsequent layers are two critical printing parameters that influence the mechanical performance of the printed concrete. This paper presents an experimental and numerical study to investigate the impacts of these printing parameters on the interlayer bond...

Micro-cantilever testing on the short-term creep behaviour of cement paste at micro-scale

This study proposes an experimental method for studying the short-term creep behaviour of cement paste at micro-scale. The micro-bending tests on miniaturized cantilever beams were used to characterize the viscoelastic properties of cement paste. The effects of w/b ratio, the type of binder and the stress level on the microscopic creep...

Investigation of drying-induced non-uniform deformation, stress, and micro-crack propagation in concrete

Concrete generally deforms and cracks in a non-uniform manner under drying-induced stress. This study used the lattice fracture model to simulate the drying-induced non-uniform deformations, stresses, and micro-crack propagation in concrete. Experiments were designed to validate the lattice fracture model, wherein the drying-induced non...

Effect of relative humidity on drying-induced damage in concrete: A comparative study of digital image correlation and lattice modelling

To assess the effect of relative humidity (RH) on drying-induced damage in concrete, the non-uniform strains and microcracks in concrete under different RH conditions were obtained using the digital image correlation (DIC) technique and lattice fracture model. The simulated non-uniform displacements were consistent with those captured using...

The Effect Of Viscosity Modifier Agent On The Early Age Strength Of The Limestone And Calcined Clay-Based Sustainable And 3D Printable Cementitious Material

Recently, our group attempted to develop the ternary blended (Portland cement, calcined clay and limestone) cementitious material for 3D concrete printing (3DCP). Due to the elimination of formwork during the layer-by-layer casting process, the printed material should have favorable elastic properties and green strength at the fresh state. A...

The Effect of Viscosity-Modifying Admixture on the Extrudability of Limestone and Calcined Clay-Based Cementitious Material for Extrusion-Based 3D Concrete Printing

To investigate the effects of viscosity-modifying admixture (VMA) on the extrudability of limestone and calcined clay-based cementitious materials, three mix designs with different dosages of VMA were proposed in this study. The ram extrusion was utilized as an extrusion model for exploring the fresh properties of printable materials. Two...

Limestone and Calcined Clay-Based Sustainable Cementitious Materials for 3D Concrete Printing: A Fundamental Study of Extrudability and Early-Age Strength Development

The goal of this study is to investigate the effects of different grades of calcined clay on the extrudability and early-age strength development under ambient conditions. Four mix designs were proposed. Three of them contained high, medium, and low grades of calcined clay, respectively, and one was the reference without calcined clay. In terms...

Feasibility of Using Low CO2 Concrete Alternatives in Extrusion-Based 3D Concrete Printing

In conventional concrete, replacing high-volume (more than 45%) of ordinary Portland cement (OPC) by supplementary cementitious materials (SCMs) is not a novel CO2 reduction method, whereas rarely in 3D printable concrete. This study attempts to explore the feasibility of using SCMs in 3D printable concrete. Initially, the existing binder mixes,...