The article describes the state of the art in reinforced geopolymers, taking into consideration various types of polymer fiber reinforcements, such as polypropylene, polyethylene, or polylactic acid. The description is focused on the usage of polymer short fibers and the mechanical properties of the geopolymer composites. However, to show a wider research background, numerous references are discussed concerning the selected studies on reinforcing geopolymer composites with long fibers and fabrics. The research method applied in the article is the critical analysis of literature sources, including a comparison of new material with other materials used in similar applications. The results of the research are discussed in a comparative context and the properties of the composites are juxtaposed with the properties of the standard materials used in the construction industry. Potential applications in the construction industry are presented. Moreover, the contemporary research challenges for geopolymer materials reinforced with fibers are presented.

Fly ash geopolymer is amorphous aluminosilicate material which is considered as alternative to Portland cement concrete. One of the limiting factors of its utilization is an increased shrinkage and related deterioration of fracture properties. This paper reports on a study of the application of multi-walled carbon nanotubes (MWCNTs) to improve the fracture properties of fly ash geopolymer. The amount of MWCNTs added varied in the range of 0.05–0.2% of the mass of fly ash. Mechanical fracture properties were determined via evaluation of three-point bending fracture tests. Specimen response during fracture tests was also monitored by means of acoustic emission, and this method was also used for the determination of cracking tendency occurring during the hardening process. Results show that the addition of MWCNTs increases the elastic modulus and compressive strength of fly ash geopolymer. However, basic fracture parameters (fracture toughness, fracture energy) firstly decreased with very small addition of MWCNTs and were regained or slightly exceeded the reference values with higher amount of MWCNTs

The aim of this paper is to quantify particularly fracture properties of selected types of mortars prepared with an alkali activated binder and hemp fibers. The main attention is focused on evaluation of three-point bending fracture tests of prismatic specimens with an initial central edge notch made of alkali activated fly ash mortars. The load versus crack mouth opening displacement (F–CMOD) diagrams were recorded during the fracture tests and subsequently evaluated using the Double-K fracture model. This model allows the quantification of two different levels of crack propagation: initiation, which corresponds to the beginning of stable crack growth, and the level of unstable crack propagation. The course of fracture tests was also monitored by acoustic emission method.

Concrete used in civil structures is usually made on cement-based matrix and natural aggregates (such as sand, gravel, crushed stone, etc.). Ceramic waste aggregate is considered as a perspective replacement of a part of natural aggregate in modern environmentally oriented building material. Concrete with natural aggregate partially replaced by ceramic waste aggregate usually show different mechanical characteristics than ordinary concrete. This paper introduces the pilot study of fatigue parameters of six concrete mixtures with various amount of ceramic waste. The experimentally obtain results are compared and discussed.