Abstract

The article presents the first results of the project under the title: ‘Development of 3D printing technology for construction and facade prefabricated elements made of concrete composites and geopolymers’, grant no. POIR.04.01.04-00-0096/18, funded by the National Centre for Research and Development in Poland, within the framework of programme: ‘Smart Growth Operational Programme 2014-2020, IV Increasing the research potential, 4.1.4: ‘Application projects’. The main aim of the project is design and development of the innovative large-format printer using geopolymers for 3D printing for residential houses. It allows the development of a technology for the production of a universal residential building, with a construction that is easy to transport and fast to assemble, as well as with the possibility of simple and quick expansion depending on the needs of users. The article shows the main idea of the advanced large format 3D printing for geopolymers with using an ergonomic printing method as well as materials research in modern filaments in the form of geopolymers.

Abstract

Cement is the most used construction material in the world (3670 MT/year are generated), being highly polluting, emitting aproximately one ton of CO2 per ton of cement. In this sector, in which the search for more sustainable materials becomes essential, the geopolymers or alkaline cements are introduced as an ecological alternative, resulting in 80% less polluting and requiring 50% less of energy comsumption in the manufacturing process.

In this context, GeoCel project is oriented to the developing of ecological construction materials to get concretes and mortars (without Portland cement) of cellular structure. Different constructive solutions were proposed for these inovative materials as wall cladding and insulation panels and  continous and draining  pavements.The caracterization of the different solutions was carried out bymechanical resistance, fire resistance and thermal conductivity tests, among others, based on the requiremens imposed at the industrial level, in order to evaluate the technical viability of the new materials. The results obtained have been promising, getting mechanical strengths superior to conventional materials  in case of mortars , as well as classification of reaction to fire A1.

Abstract

Alkali-activated materials (AAM) are now seriously considered by the cement industry as an economical alternative to Portland cement, especially for its low CO2 footprint. However, their durability still remain to be assessed in more details. The aim of this study is to focus on the sample preconditioning conditions required for testing, especially the drying stage involved in most of the current tests. Four alkali-activated binders were studied: a geopolymer (Na-silicate activated metakaolin), a Na-carbonate activated slag (GGBS), a Na-silicate activated slag and a Na-silicate activated mixture of 50% metakaolin with 50% GGBS. After an endogenous cure of 28 days at 20°C, mortar specimens were dried at different temperatures (from 20°C to 125°C) until mass stabilization. Drying kinetics and released water contents were evaluated, as well as physical, mechanical and mineralogical analyses at the end of drying. Optimal drying temperature for each alkali-activated binder was determined by coupling mechanical strength measurements and mercury intrusion porosimetry. This study revealed that an inappropriate drying temperature could modify the porosity of some classes of AAM, and reduced the compressive strength by up to 30 to 40%. Antagonistic behaviors were observed in the four alkali-activated materials studied, therefore one should be careful about selecting preconditioning protocols for assessing the properties and the durability of these binders.