Léo Demont

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• PhD. Eng MArch
• R&D Engineer - Manager of the large-scale additive manufacturing workshop at École nationale des ponts et chaussées

The vast majority of applications of extrusion-based concrete additive manufacturing deal with unreinforced mortar. The lack of reinforcement is a serious limitation for the industrial development of 3d printed concrete, because of the brittleness and lack of tensile strength of unreinforced mortar. In this paper, a new reinforcement method inspire...

Important developments in additive manufacturing with concrete have been achieved in the past decades. Yet, printed components usually do not comply with building standards or basic reliability principles, and are not commonly used as load-bearing components. A gap between research and practice exists and despite several attempts, off-the-shelf com...

The issue of reinforcement for 3D concrete printing has received considerable attention, as constructions have to comply with reliability principles and building standards. Here a specific process called Flow-Based Pultrusion for additive manufacturing (FBP), inspired by pultruded composite manufacturing and built on existing extrusion-based 3D pri...

Quality control (QC) is a key issue for extrusion-based additive manufacturing of concrete. The timely evolution of the material yield stress, called structuration, plays a key role in the stability of the printed part and its final mechanical performances [1]. With this regard, the authors have previously proposed an affordable and efficient struc...

The control of mortar rheology is of paramount importance in 3D printing concrete by extrusion. This is particularly sensitive for two-component (2K) processes that use an accelerator to switch the printed mortar very quickly from a liquid behavior to a sufficiently solid behavior to be able to be printed (i.e. structuration). After some main key p...

Significant developments in 3D concrete have been made over the past few decades. Yet, unreinforced printed components generally do not comply with existing construction standards or regulations and are therefore not used as load-bearing components. There is still a gap between research and use, and despite several proposals, standard commercial so...

Extrusion-based 3D concrete printing processes have seen significant development in the last decades. However, from a regulatory perspective, it is not possible to build with printed concrete without reinforcement, which greatly limits the scope of this technology. We therefore propose to develop a 3D printing process for fiber-reinforced concrete,...

The control of mortar rheology is of paramount importance in the design of systems and structures in 3D printing concrete by extrusion. This is particularly sensitive for two-component (2K) processes that use an accelerator to switch the printed mortar very quickly from a liquid behavior to a sufficiently solid behavior to be able to be printed. It...

This article investigates the application of a multi-robotic platform to the fabrication of complex “free-form” timber structures. A concept of “smart factory”, with a 13-DOF robotic cell combining robotic mobility with fixed workstations, is proposed. A computational workflow was implemented to allow for fast iterations during the early design sta...

Various technologies of in-line reinforcement for extrusion-based 3D printing have been proposed in the recent years. With such techniques, knowledge of the dynamic rheological properties of the extruded material is a key point for several issues, such as its ability to properly impregnate reinforcement, and possibly to pull the reinforcement thank...

This paper introduces a novel rheological technique allowing for the assessment of printable materials yield stress at nozzle exit in the case of extrusion-based 3D printing. This technique is derived from the analysis of the specific gravity-induced non-Newtonian flow that takes place at nozzle exit, which is at the origin of the formation of mate...

This work aims at proposing a strategy for 3D-printing geopolymer composite structures at a half-meter scale, without using organic additives. An original printing device based on cartridges is developed and adapted to a 6-axis robot. The yield stress, working time and apparent Young modulus of the extruded material are measured. A devoted software...

Successful and efficient fabrication using robotic extrusion of cementitious materials mainly relies on the mastering of the printable material fresh state behavior. This paper tackles this aspect by introducing a novel rheological apparatus dedicated to the yield stress measurement at nozzle exit in extrusion-based manufacturing. It is based on th...

This paper proposes a specific extrusion method for 3D printing of mortar called free deposition by the authors. It consists in letting a fine mortar flow through a moving nozzle above a support, here EPS foam. The aim is to obtain a regular lace, thus to avoid instability phenomena like coiling, and ensure a regular diameter, without stretching th...

For the tens past years, important development has been achieved on the adaptation of additive manufacturing to the construction industry using concrete. They mostly concerns control rheology at fresh state, setting time, and technology advances. Nevertheless, the reinforcement of 3D printed part remains an open question. Different reinforcement pr...

Polydon is an inflatable-deployable structure demonstrator. It is interactive and offers various spatial conditions depending on the membrane folds.

The aim of this paper is to discuss the dialectic form-finding of a complex timber structure based on an innovative structural system: shell-nexorade hybrids. Nexorades, also known as reciprocal frames are elegant structures that suffer from a relatively poor structural behavior due to in-plane shear and bending of the members. Introducing plates a...