The scaled recycled coarse aggregate concrete beam specimen tests have been simulated in finite element analysis (FEA) based analysis software, ATENA 3D, which is explicitly developed for analysis of reinforced cement concrete (RCC) structural elements. ATENA 3D offers freedom to the users to define the measured stress-strain relationship of the materials as input parameters through user define material definitions. Two numbers of scaled reinforced concrete (RC) beam specimens were tested in the laboratory and subsequently simulated to analyse the response. Each beam specimen was (125 × 250) mm in cross-section and 2100 mm long. Experimentally evaluated values of compressive strength, split tensile strength and elastic modulus of concrete besides reported values of thermal coefficients and Poisson’s ratio of concrete have been used as inputs against default inputs to explore the enhancement in the quality of simulation. Furthermore, in order to explore the potential for enhancing the simulation, the utilization of measured stress-strain relationship for the materials has been examined as an alternative to the default values. For subsequent analysis, a commonly reported constitutive relationship for recycled coarse aggregate concrete, as reported in the literature, has been considered. In addition to strength, the load deformation characteristics of simulated beams were compared to those of beam specimens examined in the laboratory. The outcomes show that, tends of load carrying capacity reflect similar behavior, especially with due consideration of appropriate input parameters.
This research explores the durability performance of ternary blended concrete made using industrial by-products ground granulated blast furnace slag (GGBFS) and microfine (MF) as partial replacements for ordinary Portland cement (OPC), along with manufactured sand (MS) as a sustainable alternative to river sand. M30-grade concrete mixes were prepared, including a control mix and a ternary blend (G3M4) comprising 30 % GGBFS, 20 % MF, and 50 % OPC. Durability assessments were carried out by exposing the specimens to acidic (5 % HCl + 5 % H2SO4) and saline (10 % NaCl) environments. Compressive strength and weight loss were evaluated at 28, 56, 90, and 180 days. The G3M4 mix showed significantly better performance, with lower weight reduction (7.64 % in acid and 4.98 % in salt exposure) than the control mix (12.99 and 5.35 %, respectively). Likewise, strength loss was minimized in the G3M4 mix, recording reductions of 45.41 % under acid and 6.88 % under salt exposure versus 52.08 and 9.44 % for the control. These improvements are credited to the denser matrix and increased chemical resistance from the combined use of GGBFS and MF. The study highlights the potential of ternary blended concrete with MS in enhancing durability under harsh conditions, promoting more sustainable construction solutions.
The large CO2 emissions of the construction sector have spurred research for environmentally friendly alternatives. CO2-activated concrete strengthens, according to carbon cure and Solidia company, and it permanently stores carbon. This research evaluated mechanical properties of dry ice infused concrete at 10, 20, and 30 % shows incremental strength trend up to 20 % over the control mix, CO2-infused concrete increases compressive, flexural, and split tensile strength, hence strengthening the resultant structure. It resists H2SO4) and HCl to some degree; MgSO4 greatly increases strength. NaCl has no advantages, though. Including CO2 into concrete could increase sustainability and performance, therefore lowering the environmental effect in construction.
The increasing demand for sustainable infrastructure, coupled with the need for materials that can withstand aggressive environments, has driven researchers to develop highperformance concrete with reduced carbon emissions and enhanced durability. This study is undertaken to address these challenges by exploring the mechanical performance, workability, microstructural behavior, and environmental impact of ultra high-performance concrete (UHPC) incorporating supplementary cementitious materials (SCMs) such as fly ash, ground granulated blast furnace slag (GGBFS), and microfine particles. Six UHPC trial mixes (TM01–TM06) were developed with a fixed water-to-binder ratio of 0.2 and evaluated through compressive, split tensile, and flexural strength tests at 7, 28, and 56 days. TM04, which included steel fibers, achieved the highest mechanical performance, showing a 25 % increase in compressive strength and a 20-30 % improvement in tensile and flexural strength compared to fiber-free mixes. Workability was assessed using slump flow tests, where TM01 and TM02 showed better flow retention (~5 % loss), while TM06 experienced a 9 % drop due to the presence of steel fibers. SEM analysis confirmed that TM04 exhibited a denser microstructure with uniformly distributed N-A-S-H and C-AS-H gels and reduced porosity, while TM01 showed scattered gel formations and micro-voids. In terms of environmental impact, TM04 and TM05 containing higher SCM content with 40 % cement reduction achieved up to 35 % lower carbon emissions compared to TM01. Life cycle assessment (LCA) results also showed that TM03 achieved an 18 % reduction in embodied CO2 emissions (E-CO2). These findings highlight the potential of SCM- and fiber-enhanced UHPC mixes to deliver high strength, improved durability, and reduced environmental footprint, making them suitable for modern, sustainable construction applications.
This research article investigates the thermo-hygro coupled mechanical behavior of high-performance concrete (HPC) under severe transient heating conditions, specifically from ambient temperatures rising to 1000°C for a duration of four hours. The experimental study reveals that HPC mix designs containing supplementary cementitious materials (SCMs) are highly susceptible to thermally induced spalling. It was found that the chemically bonded saturated moisture within the highly durable concrete matrix significantly contributes to explosive spalling, more so than free saturated moisture during transient heating conditions. Under unrestrained conditions, HPC blocks that are subjected to severe heating conditions on one side are especially prone to developing pore pressure at a depth of 20 mm from the heating exposure surface. Nominal spalling has been observed in the concrete matrix at temperatures ranging from 126 to 266°C. This phenomenon is identified by the presence of surface cracks throughout the concrete blocks. In contrast, explosive spalling occurs at higher temperatures, specifically ranging from 325 to 449°C, leading to significant damage to the concrete matrix. It is also observed that within the range of 325 to 449°C in the concrete matrix, the phase change of saturated moisture to vapor increases the heat transmission rate in the concrete matrix. It is essential to address these issues in order to improve the behavior of concrete at elevated temperatures. This research outcome may aid in the development of new techniques to mitigate concrete spalling and enhance the safety and integrity of reinforced concrete (RC) structures, especially under severe fire conditions. Ultimately, this can help reduce the risk of failure or collapse and improve the fire resistance rating of RC structures.
This study investigates rebar corrosion in geopolymer concrete with three water-to-binder ratios (0.45, 0.5, and 0.55) and two binder contents: ground granulated blast furnace slag (GGBS) alone or equal fractions of fly ash (FA) and GGBS. The corrosion performance of embedded rebar in geopolymer concrete was tested in wet (7 days) and dry (14 days) cycles with 3.5 %, 5 %, and 7.5 % NaCl. The cast cylindrical specimens were tested for half-cell potential and corrosion current density using linear polarization resistance (LPR) after 28 days ambient curing at 1, 7, and 150 days per ASTM G109 for each exposure condition. The cube specimen was tested for compressive strength at 7 and 28 days of curing. Binders, water-to-binder ratio, testing age, and NaCl exposure percentages affect geopolymer concrete rebar corrosion. Due to decreased pore size and greater C-A-S-H and N-A-S-H gel formation, GGBS-based geopolymer concrete has a higher compressive strength than fly ash and GGBS. A blend of fly ash and GGBS-based geopolymer concrete with a waterto-binder ratio of 0.55 had a higher corrosion risk based on the investigation.
The need to reduce carbon emissions from cement production necessitates the development of more environmentally friendly construction methods. The purpose of this research was to investigate the long-term corrosion behaviour of steel rebar embedded in concrete with natural zeolite fine aggregate and powder (ZP) as a partial substitution. The goal was to reduce CO2 emissions from the concrete manufacturing sector and improve stable CO2 sequestration in the matrix of concrete under macrocell corrosion conditions for a period of one year. The present study investigated the performance of rebar placed in concrete composed of 100 % ordinary Portland cement (OPC), 85 % OPC+15 % ZP, 85 % Portland pozzolana cement (PPC)+15 % ZP and 85 % Portland slag cement (PSC)+15 % ZP under accelerated carbonation. Following the initial water curing for 28 days, the reinforced concrete samples were placed in a sodium bicarbonate (NaHCO3) solution with a concentration of 0.5 M and 0.75 M. The carbonation depth measurement test was conducted to ascertain the degree of carbonation after 365 days of exposure. The corrosion performance of steel rebar was assessed by measuring the macrocell total corrosion after each wet-dry cycle. Fourier transform infrared spectroscopy (FTIR) measurements were done to evaluate the extent of carbonation in each mix. Results showed 100 % OPC had lower carbonation depth and macrocell total corrosion than binder incorporated with ZP, indicating greater carbonation in zeolite containing concrete. Additionally, specimens cured with 0.5 M and 0.75 M carbonated solution had higher carbonation depth, macrocell total corrosion and CO2 sequestration within the concrete matrix compared to those cured with the normal water.
July 2025
Volume - 99
Number : 07
June 2025
Volume - 99
Number : 06
May 2025
Volume - 99
Number : 05
April 2025
Volume - 99
Number : 04
March 2025
Volume - 99
Number : 03
February 2025
Volume - 99
Number : 02
January 2025
Volume - 99
Number : 01
December 2024
Volume - 98
Number : 12
November 2024
Volume - 98
Number : 11
October 2024
Volume - 98
Number : 10
September 2024
Volume - 98
Number : 09
