Biranchi Panda

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.

Flow and mechanical properties of 3D printed cementitious material with recycled glass aggregates

Environmental sustainability has been the focus of recent construction trends. Adopting efficient construction technologies and minimizing the usage of raw materials are a few of many ways to achieve such sustainability. In the past few years, 3D printing of concrete has received considerable attention for its potential to be the next disruptive technology for construction industry. By eliminating and/or reducing the amount of in-situ construction, combined with the need for skilled personnel, 3D printing can help in achieving good quality control at construction site, which has long been an issue in traditional construction industry. Singapore is dependent on neighboring countries for raw construction materials. Using recycled materials as a substitute for aggregates not only minimizes the usage of raw materials, but also help in reducing the Singapore’s dependency on other countries in long-term. In this study, preliminary findings of a 3D printed cementitious material with recycled glass aggregates (RGA) were presented. For 3D printing two different binder systems were used – ternary blended Portland cement and flyash based geopolymer.

Effect of 3D Printing on Mechanical Properties of Fly Ash-Based Inorganic Geopolymer

The inorganic polymer, e.g. geopolymer, is well known as a green construction material with its remarkable mechanical and durability properties compared to other ceramic and Portland cement-based materials. It is worth promising to explore such geopolymer properties processed by a recent innovative technology, i.e. 3D concrete printing, which has established its ground in the construction industry. This study is focused on examining the directional effect of 3D printing process on compressive strengths of geopolymer mortar made from different industry by-products such as fly ash, slag, silica fume, etc. For a comparison, the same geopolymer mix was casted and cured in ambient temperature prior to its mechanical test with printed samples. Results from experimental tests revealed an anisotropy in the compressive strengths caused due to layered deposition of the geopolymer mortar.

Time gap effect on bond strength of 3D-printed concrete

ABSTRACT An advancing technology that combines the concrete extrusion with a motion control to create structures with complex geometrical shapes without the need for formwork is known as 3D concrete printing. Since this technique prints layer by layer, the time taken to reach the same position in the subsequent layer is important as it will create an anisotropic property that has a weaker tensile strength at the bond interface of the two printed filaments. Through rheological measurement, which reveals the material deformation and flow behaviour, it is possible to examine the material structural build-up due to time-gap effect by measuring at different time delay. This paper focuses on investigating the time-gap effect on the printed filament with rheological and observation at macroscopic-scale to understand the material behaviour of the initial and subsequent printed layer during its fresh phase. Rheological experiment findings reveal that the tensile strength of the printed specimen is correlated to the material modulus at the initial layer.

Bond Strength in 3D Printed Geopolymer Mortar

3D printing is getting significant attention in the construction industry. This technology, which has been talked for years, is now delivering tangible results, however it is not yet ready for mass production in mainstream construction. Thixotropy material, 3D printer together with 3-dimensional computer model are the key elements required for robust concrete printing. For a freshly printed material, the increase in structural buildup at rest, prior to the placement of a successive layer can result poor interlayer bond strength and therefore, in this paper, we aimed to investigate the structuration effect of a nano-clay modified geopolymer, used for 3D concrete printing. Different structuration rate was achieved by changing molar ratio of activator and experimental results conclude that, there exists an optimum printing zone for different molar ratios, beyond which interlayer bond strength will be very weak.