Properties and Performance of Concrete Materials and Structures

The Special Issue on “Properties and Performance of Concrete Materials and Structures” presents the current and relevant research and advances in the field of concrete composites, as well as covering a broad range of experimental studies in relation to high-performance, fiber-reinforced, self-compacting, and eco-efficient concrete materials and structures. Furthermore, analytical studies and numerical simulations are presented to show developments in the design methods of concrete composites. This Special Issue collects the most recent experimental techniques, analytical and numerical methods in relation to concrete materials and structures

A Green Way of Producing High Strength Concrete Utilizing Recycled Concrete

Multiple studies have investigated the influence of recycled aggregates derived from concrete waste on the efficacy of structural concrete manufactured in recent times. By utilizing recycled aggregates obtained from construction and demolition debris, it is possible to safeguard natural aggregate resources, reduce the demand for landfill space, and promote the utilization of sustainable building materials. However, compared to natural aggregate, bonded cement mortar on recycled concrete aggregate exhibits higher porosity, greater water absorption capacity, and lower strength. The mechanical and durability characteristics of freshly poured and hardened concrete made from recycled concrete aggregate are adversely affected as a result. This study presents comprehensive experimental research aimed at examining the residual mechanical properties and resistance to acid attack of normal and high-strength mixes of recycled aggregate concrete (RAC) using the compressible packing model. Recycled aggregate was employed as both coarse and fine aggregate. The recycled concrete samples were prepared in a manner that corresponded to the proportions of both the coarse and fine aggregates. Twelve mixtures were designed and cast, and their performance was evaluated based on various strength parameters (compressive strength, splitting tensile strength, and flexural strength) as well as acid attack resistance properties (porosity and ultrasonic pulse velocity). The findings indicate that recycled concrete aggregate can be utilized in the production of high-strength concrete, with mechanical property values that are significantly acceptable compared to concrete containing natural aggregates. Moreover, the addition of Silica Fume as a cement replacement in concrete plays a crucial role in enhancing sulphate resistance. In terms of concrete product utilization, recycled concrete and its significance in this study played a crucial role in environmental preservation. Doi: 10.28991/CEJ-2023-09-10-08 Full Text: PD

New Frontiers in Cementitious and Lime-Based Materials and Composites

Cement and lime currently are the most common binders in building materials. However, alternative materials and methods are needed to overcome the functional limitations and environmental footprint of conventional products. This Special Issue dedicated to “New frontiers in cementitious and lime-based materials and composites” gathers selected reviews and experimental articles that showcase the most recent trends in this multidisciplinary field. Authoritative contributions from all around the world provide important insights into all areas of research related to cementitious and lime-based materials and composites, spanning from structural engineering to geotechnics, including materials science and processing technology. This Topical Collection is intended to foster innovation and help researchers and developers to identify new solutions for a more sustainable and functional built environment

An Experimental Investigation on Metakaolin Modified Concrete Paver Blocks

Concrete paver blocks are special pre-cast pieces of concrete blocks of non-interlocking or interlocking types, commonly used in exterior landscaping pavement applications. Properly designed and constructed paver blocks give excellent performance at locations where conventional pavement systems have lower service life due to a number of environmental, geological constraints. But with the use of high performance concrete they can be designed to sustain light, medium, heavy and very heavy traffic conditions under any constraints. Modern concrete can be modified with addition of mineral admixtures which refine the microstructures of the concrete and enhance its physical properties and durability. Metakaolin, produced by controlled thermal treatment of kaolin, can be used as a concrete constituent, since it has pozzolanic properties. It is a highly efficient Pozzolana and react rapidly with the excess calcium hydroxide resulting from OPC hydration by a pozzolanic reaction, to produce calcium silicate hydrate and calcium alum inosilicate hydrates. Hence the objective of the present work was to evaluate the performance of concrete modified with Metakaolin for paver blocks for use in pavements and other application areas. As compressive, flexural strengths and water absorption are the most significant properties for concrete paver blocks the same have been studied for various concrete mixes with varying percentages of Metakaolin. Metakaolin was used as partial replacement of cement in the study and three percentages 5%.10% and 15% were adopted for determination of compressive strength, flexural strength and water absorption of zigzag, dumbel and I shape paver blocks. The mix with 10% replacement was found to give maximum compressive, flexural strength and minimum water absorption for all types of paver blocks. To validate the above conclusion XRD, FESEM and EDS analysis of the MK modified mixes were done and found that addition of MK to concrete made microstructure very dense, thereby improving its propertie

Investigating the governing factors influencing the pozzolanic activity through a database approach for the development of sustainable cementitious materials

Pozzolans, known to possess high pozzolanic activity, enhances the long-term engineering properties of concrete due to the consumption of calcium hydroxide and the consequent formation of the calcium-silicate-hydrate gels within the cementitious matrix. Although the key factors that affect the pozzolanic activity such as the chemical composition, amorphousness, and fineness are commonly addressed in literature, there is a growing need to further gain an insight into the factors that govern this activity in a more comprehensive approach. The aim of this empirical study is to develop concrete models comprising optimal replacement of pozzolans based on the governing factors affecting the activity through the database approach. The database, consisting of 631 number of data points harvested from the literature, is established to determine the optimum replacement levels of the designated pozzolans in concrete. The governing factors therefore played a key role in establishing the boundary conditions that enabled the potential concrete models to be generated particularly for the sustainability assessment of concrete incorporating pozzolans. The study shows that the optimum replacement levels in con- crete mixtures are 15–50% for GGBS, 10–35% for fly ash, and 5–15% for silica fume. The study furthermore demonstrated that the utilisation of these substitutions leaded a considerable reduction in carbon emissions that ranged from 13% to 43% for GGBS, 9–31% for fly ash, and 4–13% for silica fume. The study significantly contributes to the generation of greener construction materials, and offers a cleaner disposal route for the pozzolans principally compared to the traditional waste management alternatives