Nowadays, mortar and concrete systems are not just simple building materials made of water, cement, and aggregate. The demands for building materials in terms of technical, ecological, and economic properties are constantly increasing, especially due to the growing importance of building maintenance and repair. Therefore, repair materials are continuously subject to innovation, with a particular focus on binder systems in research and development. The modification and variation of individual components allows for the adjustment of processing and usage properties adapted to the application. The synergistic use of mineral and organic binder components enables the achievement of diverse and optimal properties.

However, researching the mechanical and physical properties of such systems is typically very time-consuming. The numerous possibilities for variations in components and the dosage quantities result in a large number of potential formulations. The mechanical properties of these formulations are usually determined through quasi-static tests on relatively large test specimens at room temperature. If there is a need to have additional information on the temperature- or moisture-dependent behavior of the materials, it will result in a test matrix that requires a significant amount of time and material.

The objective is to develop a new technique for characterizing the mechanical properties of functionalized binder systems under varying environmental conditions. In the present contribution, a high-load dynamic-mechanical measuring system for solids will be presented to investigate the mechanical behavior of small test specimens using dynamic loading at defined temperatures or humidity levels. Examples of dynamic-mechanical analyses of selected binder systems composed of organic and mineral components are shown. The initial results indicate that the DMA investigation method can significantly contribute to the development and research of new and existing binder systems.

The construction sector faces the challenges and obligations of handling and reducing the use of raw materials and increasing the reuse and recycling streams of waste disposal. The incorporation of industrial by-products in cementitious composites and the use of locally sourced materials contributes towards producing cementitious building materials with lower embodied energy, yet acceptable mechanical properties, thus promoting sustainability within the construction industry. This study investigates the utilization of limestone quarry waste and silica fume, as partial replacement to fine sand and cement, respectively, in cementitious composites. The limestone waste material used as filler in this study originated from a local quarry, while the silica fume was imported. Various cementitious mixtures were designed and produced in the laboratory, following a parametric design process, whereby alternative proportions of the industrial by-products were used. During the design of the mixtures, specific performance objectives were set. The physico-mechanical properties of the hardened composites were rigorously examined at different curing ages to assess the effect of the industrial by-products on the cementitious mixtures hereby produced. The results highlight the potential of the utilization of industrial by-products in cementitious composite materials. Mixtures with silica fume showed better enhancement in compressive strength between 7 and 28 days of curing, compared to mixtures without silica fume. The workability assessment of the mixtures in the fresh state confirmed the feasibility and practicality of the manufacturing process of the specific composites. These findings project a potential avenue for the utilization of limestone quarry waste and silica fume as sustainable alternatives in cementitious material production, thus offering pathways to reduce the environmental impact of these materials while maintaining or improving their physico-mechanical properties. The incorporation of the aforementioned substitute waste materials contributes to the promotion of ecologically conscious activities and meets the desires of the public for greener building materials.

The Mars colonization vision is progressing faster than anticipated, due to rapid advancements in space exploration technology, which pave the way for future Mars missions. Addressing challenges such as extreme low temperatures, lack of substantial atmosphere, and resource scarcity on Mars is essential for successfully establishing sustainable habitats and infrastructure.In this study, a bio-synthesis hydrogel-based concrete (Bio-HBC) containing a physically crosslinkable sand-hydrogel scaffold and genetically engineered yeast cells - S. cerevisiae capable of expressing proteins on the yeast's cell surface was recently developed. Here, Bio-HBC design factors, i.e., yeast/gelatin ratio, sol/sand ratio, curing regimes, and types of protein expressed, are evaluated.

Bio-HBCs were produced using various yeast-to-gelatin ratios, ranging from 0:5 to 5:0. To mimic the Martian environment, curing conditions that replicated extreme low temperatures (-48°C) and low atmospheric pressure (8 Pa) were adopted. These Bio-HBCs were examined for mechanical properties, microstructural properties, and recovery of original properties in successive generations. The results indicate that the compressive strength and elastic modulus of Bio-HBCs initially increased with the yeast/gelatin ratio, peaked at a critical value, and subsequently decreased. Specifically, a 3:7 yeast/gelatin ratio achieved an average compressive strength of 11.9 MPa and an elastic modulus of 398.9 MPa. Notably, the findings reveal that abiotic HBCs have significant regeneration potential, as they maintained their properties through three successive material generations.

Ultra-high performance concrete (UHPC) has become increasingly popular for several applications, e.g. bridge structures joints, because of its superior mechanical performance. However, the large-scale implementation of UHPC for full structural members is yet to be fully realized because of the high cost associated with the material. Emerging UHPC uses local and sustainable materials that can be economically feasible and environmentally sustainable. This study explores the structural performance of eco-UHPC with recycled steel fibers (RSF) and manufactured steel fibers (MSF) for full precast bridge columns. Two sets of identical 1/3-scale bridge columns were fabricated at a precast plant, including four footing foundations with conventional concrete. The specimens were tested under combined axial and quasi-static cyclic lateral force at the Earthquake Engineering Laboratory of the University of Nevada, Reno. This preentation will provide an overview of the test results and comparison of structural behavior of columns with recyceld and high-end steel fibers.

Concrete rehabilitation has become increasingly important due to the need to maintain and improve the performance of existing structures. Among the various techniques available for concrete rehabilitation, active techniques such as prestressing strengthening methods have proven to be highly sustainable solutions. One of the most used prestressing strengthening applications involves placing externally unbonded post-tension tendons on the element due to its ease of construction and cost-effectiveness.

However, external post-tensioning (EPT) strengthening techniques exhibit multiple nonlinear behaviors mainly due to material responses to loading, geometrical disorders during loading, and variations in behavior between unbonded tendons and concrete deformations. These uncertainties can compromise the sustainability of the rehabilitated structure, meaning it may not operate as intended. As a result, numerous studies have been conducted to predict the ultimate tendon stress in EPT beams and determine their flexural strength. However, a more rational, accurate, and functional approach is still needed.

Therefore, this research aims to propose a practical prediction model of the ultimate tendon stress by employing machine learning techniques, specifically tree-based machine learning algorithms. To this end, a comprehensive dataset is created in this research using 32 experimental studies from the literature, which comprises 133 reinforced concrete beams strengthened with unbonded EPT tendons (24 beams were strengthened with FRP tendons while the other 109 were high-strength steel). In addition, a thorough comparison has been made with four design code models and four rational models found in the literature, with theoretical analyses based on specific section or whole member examinations.

Based on this rigorous comparison, the ensemble learning algorithms utilized in this research have demonstrated their reliability. These models have shown high accuracy and low error percentages (MAPE <10%). Furthermore, It has been observed that the variation in tendon eccentricity, along with its initial effective strain, holds significance in many machine-learning prediction models.