Suvash Chandra Paul

3D printing trends in building and construction industry: a review

ABSTRACT Three-dimensional (3D) printing (also known as additive manufacturing) is an advanced manufacturing process that can produce complex shape geometries automatically from a 3D computer-aided design model without any tooling, dies and fixtures. This automated manufacturing process has been applied to many diverse fields of industries today due to significant advantages of creating functional prototypes in reasonable build time with less human intervention and minimum material wastage. However, a more recent application of this technology towards the built environment seems to improve our traditional building strategies while reducing the need for human resources, high capital investments and additional formworks. Research interest in employing 3D printing for building and construction has increased exponentially in the past few years. This paper reviews the latest research trends in the discipline by analysing publications from 1997 to 2016. Some recent developments for 3D concrete printing at the Singapore Centre for 3D Printing are also discussed here. Finally, this paper gives a brief description of future work that can be done to improve both the capability and printing quality of the current systems.

Processing and Properties of Construction Materials for 3D Printing

3D printing (3DP), commonly known as additive manufacturing (AM), is a promising technology that can fabricate three dimensional complex shape prototypes directly from computer-aided design (CAD) model without any tooling and human intervention. Owing to its peculiar characteristics, AM is widely used in many industries to assist in the design, manufacture and commercialization of a product. More recently, this technology has been extended to building and construction (B&C) application in order to mitigate some of the critical issues such as shortage of skilled labour, high production cost and construction time, health and safety concerns of the workers in the hazardous environment etc. However for successful implementation, proper selection of materials and their mix design is highly recommended, which is a challenging task. This paper summarizes the current available 3DP systems from literature and the respective materials that have been used thus far by various experts, industries for B&C purposes. Finally, the benchmarking properties of theses material and potential research directions are briefly discussed.

Reinforcing Bar Corrosion

Currently, a common use for strain-hardening cement-based composites (SHCC) is as a repair material, or for retrofitting reinforced concrete (RC) structures. This is due to SHCC being expected to have high resistance to substance penetration as the cracks that are produced in SHCC are fine. Equally, in retrofitting applications such as those described in Sects. 1.5.3– 1.5.5, or in applications of steel-reinforced SHCC (R/SHCC) in structures in coastal regions, the corrosion of the steel reinforcement is likely to determine both durability and structural service life. Accordingly, this chapter discusses the chloride-induced corrosion of R/SHCC. From reported experimental results, chloride profiles in cracked R/SHCC have been reported in Chap. 2. Here, the chloride contents are evaluated for correlations with observed corrosion damage in the steel bars for different cover depths in cracked R/SHCC. Steel bar damage is expressed in terms of steel mass loss, corrosion depth, and reduction in yield resistance. Finally, a corrosion model is proposed for R/SHCC, incorporating crack width, crack spacing, free chloride content, and cover depth.

A review of 3D concrete printing systems and materials properties: current status and future research prospects

Three-dimensional printing of concrete (3DPC) has a potential for the rapid industrialization of the housing sector, with benefits of reduced construction time due to no formwork requirement, ease of construction of complex geometries, potential high construction quality and reduced waste. Required materials adaption for 3DPC is within reach, as concrete materials technology has reached the point where performance-based specification is possible by specialists. This paper aims to present an overview of the current status of 3DPC for construction, including existing printing methods and material properties required for robustness of 3DPC structures or structural elements.,This paper has presented an overview of three categories of 3DPC systems, namely, gantry, robotic and crane systems. Material compositions as well as fresh and hardened properties of mixes currently used for 3DPC have been elaborated.,This paper presents an overview of the state of the art of 3DPC systems and materials. Research needs, including reinforcement in the form of bars or fibres in the 3D printable cement-based materials, are also addressed.,The critical analysis of the 3D concrete printing system and materials described in this review paper is original.

A review of the mechanical and durability properties of strain hardening cement-based composite (SHCC)

This review paper covers the current state of the art and cases of successful applications of innovative materials in the field of concrete and in particular, the current and possible future uses of strain hardening cement-based composite (SHCC) in structural and non-structural concrete. It also presents an extensive overview of existing results and background of the mechanical and durability aspects of SHCC in relation to reference concretes. Research articles on SHCC indicate that its pseudo strain-hardening behavior can be an alternative solution to the impasse of normal concrete in ductility, tensile and flexural strength, and crack widths. Though research works on SHCC have been conducted in some countries, however, as a new material, the literature on SHCC, especially its durability properties is still limited. Some of the existing results are yet to be tested on the field, hence the limited applications of SHCC.

Automation of Robotic Concrete Printing Using Feedback Control System

In recent years, digital fabrication is termed as “third industrial revolution” and its interaction with extrusion based cementitious material has been well known as concrete printing. In concrete printing, a gantry/robotic system deposits concrete layer by layer following G-codes generated from slicing of the 3D component. However, the robotic system does not consider the material (concrete) properties and component geometry which sometimes cause failure in the printing process. Concrete properties are usually attributed with time and therefore the system parameters such as extruder velocity and layer height are necessarily to be controlled accordingly to obtain an uninterrupted smooth flow. In line with this, our current research aims to automate the printing process by collecting material’s fresh properties through a feedforward control system. A six-axis industrial Denso® robot was used for 3D printing of geopolymer concrete with the help of screw pump and ten-millimeter circular extruder. The obtained experimental results confirmed the validity and robustness of this