EFFECT OF WATER-CEMENT RATIO, CEMENT DOSAGE, TYPE OF CEMENT AND CURING PROCESS ON THE DEPTH OF CARBONATION OF CONCRETE

In recent years, the durability of concrete has been the subject of a few research projects carried out by several scientific and technical centres. As a major cause of concrete degradation around the world, reinforcing steel corrosion requires our full attention. This article analyses one of the phenomena at the origin of these disorders, namely the carbonation of concrete, and proposes some provisions to guard against it. The article is divided into two parts; the first describes the causes and consequences of the chemical process of carbonation as well as the means to protect it. The second deals with the influence factors on carbonation such as the minimum cement dosage, the type of cement, the water-cement ratio (W/C) and the reinforcement coating. Indeed, prismatic specimens (15 x 15 x 60 cm3) and cubic specimens (15 x 15 x 15 cm3) were made for different mixtures and with a W/C ratio of 0.50, 0.55 and 0.60. The prismatic specimens were subjected to a carbonation test, while the cubic specimens were used to determine the compressive strength, the corresponding density and the immersion water absorption

Fracture analysis of steel fibre-reinforced concrete using Finite element method modeling

Concrete has a great capacity to withstand compressive strength, but it is rather weak at resisting tensile stresses, which ultimately result in the formation of cracks in concrete buildings. The development of cracks has a significant impact on the durability of concrete because they serve as direct pathways for corrosive substances that harm the concrete’s constituents. Consequently, the reinforced concrete may experience degradation, cracking, weakening, or progressive disintegration. To mitigate such problems, it is advisable to include discrete fibres uniformly throughout the concrete mixture. The fibers function by spanning the voids created by fractures, therefore decelerating the mechanism of fracture initiation and advancement. It is not practical to assess the beginning and spread of cracks when there are uncertainties in the components and geometrical factors through probabilistic methods. This research examines the behaviour of variation of steel fibers in Fiber Reinforced Concrete (FRC) via Finite Element Method (FEM) modeling. In this study also the fracture parameters such as fracture energy, and fracture toughness have been computed through FEM analysis. The FEM constitutive model developed was also validated with the experimental result. The compressive strength of the developed constitutive model was 28.50 MPa which is very close to the 28-day compressive strength obtained through the experiment, i.e., 28.79 MPa. Load carrying capacity obtained through FEM was 7.9 kN, 18 kN, and 24 kN for three FEM models developed for three varying percentages of steel fiber 0.25%, 0.5%, and 0.75% respectively. The study developed a FEM model which can be used for calculating the fracture parameters of Steel Fibre-Reinforced Concrete (SFRC)

Flexural behavior of reinforced concrete beams under instantaneous loading: Effects of recycled ceramic as cement and aggregates replacement

The flexural behavior of five reinforced concrete beams containing recycled ceramic as cement and aggregate replacement subjected to a monotonic static load up to failure was studied. A full-scale, four-point load test was conducted on these beams for 28 days. The experimental results were compared with the conventional concrete as a control specimen. The cross-section and effective span of these beams were (160 × 200 mm) and 2200 mm, respectively. The data recorded during the tests were the ultimate load at failure, steel-reinforcement bar strain, the strain of concrete, cracking history, and mode of failure. The beam containing 100% recycled aggregates displayed an ultimate load of up to 99% of the control beam specimen. In addition, the first crack load was almost similar for both specimens (about 14 kN). The deflection of the beam composed of 100% of the recycled aggregates was reduced by 43% compared to the control specimen. Regardless of the recycled ceramic aggregates ratio, quantities such as service, yield, and ultimate load of the proposed beams exhibited a comparable trend. It was asserted that the ceramic wastes might be of potential use in producing high-performance concrete needed by the structural industry. It might be an effective strategy to decrease the pressure on the environment, thus reducing the amount of natural resources usage

Utilization of millet husk ash as a supplementary cementitious material in eco-friendly concrete: RSM modelling and optimization

The environment has been greatly impacted by the increase in cement consumption. However, a huge quantity of energy is consumed and large amount of poisonous gases releases into the atmosphere during the cement production, which harms the environment. In order to decrease not only cement manufacturing but also energy usage and to aid in environmental protection, scientists are attempting to introduce agricultural and industrial waste materials with cementitious characteristics. Therefore, millet husk ash is used as supplementary cementitious material (SCM) in the concrete for producing sustainable environmental. The main purpose of this investigation is to check the workability, compressive strength, splitting tensile strength, flexural strength and drying shrinkage of concrete incorporating 0 %, 5 %, 10 %, 15 % and 20 % of MHA as SCM in concrete. A total of 165 concrete samples was made with mix proportion of 1:1.5:3 and cured at ages of 7, 28, and 90 days. The investigational outcomes displayed that there was an improvement in compressive strength, tensile strength, and flexural strength by 11.39 %, 9.80 %, and 9.39 %, correspondingly, at 10 % of MHA replacement of cement. Also, the water absorption reduced as MHA content increased after 28 days. There was also a reduction in drying shrinkage of concrete as the MHA increased after 28 days. Though, the workability is declined as the proportion of MHA increased in concrete. Moreover, the embodied carbon is declined while the content of PC substituted with MHA rises in concrete. In addition, response prediction models were built and validated using ANOVA at a 95 % significance level. R2 values for the models varied from 87.47 to 99.59 percent. The study concludes that the accumulation of 10 % MHA in concrete has a favourable effect on the characteristics of the concret

BIM-driven energy simulation and optimization for net-zero tall buildings: sustainable construction management

The growing demand for sustainable and energy-efficient buildings, particularly in the context of tall structures, has prompted increased attention to innovative solutions. Despite advancements in Building Information Modelling (BIM) technology, there exists a critical gap in understanding its comprehensive application for achieving net-zero energy consumption in tall buildings, particularly in the Malaysian construction industry. This research addresses this gap by presenting a novel strategy that integrates BIM technology with energy analysis tools for net-zero tall buildings in Malaysia. The aim of the study is to contribute valuable insights to the construction industry, policymakers, and researchers by conducting empirical research, utilizing case studies, validating the proposed framework, advancing sustainable design practices, and supporting the transition towards net-zero energy tall buildings in Malaysia. The methodology involves a three-phase approach, including qualitative analysis, a pilot survey, and a main questionnaire. Exploratory factor analysis (EFA) validates the categorization derived from qualitative interviews, while Partial Least Squares Structural Equation Modelling (PLS-SEM) assesses the convergent and discriminant validity of the measurement model. Hypotheses testing using bootstrapping establishes the significance of correlations between BIM deployment and key factors such as early design integration, enhanced energy efficiency, optimized system integration, predictive performance analysis, and validation of sustainable design. The research findings support the positive associations between BIM deployment and the mentioned factors, providing statistical significance through T-statistics and p-values. The implications of this research extend beyond the Malaysian context, offering valuable insights for architects, engineers, and stakeholders involved in designing and managing sustainable tall buildings. By addressing the identified gaps and leveraging BIM technology effectively, stakeholders can contribute to the construction of net-zero energy structures, aligning with global efforts towards sustainable and energy-efficient building practices

Experimental Study of the Usability of Recycling Marble Waste as Aggregate for Road Construction

The road construction industry consume a considerable amount of natural aggregates in the world. As a consequence, the increase in the natural aggregates demand increases the construction cost. On the other hand, marble spoil waste, generated from marble cutting and polishing process, is an environmental nuisance in the world. Indeed, an economical solution to this problem is the reuse of these wastes as an aggregates for road construction. The main objective of this study is to evaluate the usability of aggregate, obtained by crushing marble waste, as a conventional aggregate for road construction using an experimental investigation. To achieve this objective, these experimental tests were carried out on fine and coarse marble aggregate samples: sieve analysis, Atomic Absorption Spectrometry, calcium carbonate content, scanning electron microscope (SEM), X-Ray- diffraction (XRD), densities, water absorption, equivalent of sand, Los Angeles, Micro Deval, flakiness index, and shape index. Finally, experimental test results show that the chemical composition and the physical and mechanical properties of marble aggregate recommend it to be used as a conventional aggregate for road construction

Experimental Study of the Usability of Recycling Marble Waste as Aggregate for Road Construction

The road construction industry consume a considerable amount of natural aggregates in the world. As a consequence, the increase in the natural aggregates demand increases the construction cost. On the other hand, marble spoil waste, generated from marble cutting and polishing process, is an environmental nuisance in the world. Indeed, an economical solution to this problem is the reuse of these wastes as an aggregates for road construction. The main objective of this study is to evaluate the usability of aggregate, obtained by crushing marble waste, as a conventional aggregate for road construction using an experimental investigation. To achieve this objective, these experimental tests were carried out on fine and coarse marble aggregate samples: sieve analysis, Atomic Absorption Spectrometry, calcium carbonate content, scanning electron microscope (SEM), X-Ray- diffraction (XRD), densities, water absorption, equivalent of sand, Los Angeles, Micro Deval, flakiness index, and shape index. Finally, experimental test results show that the chemical composition and the physical and mechanical properties of marble aggregate recommend it to be used as a conventional aggregate for road construction

Impact of Window to Wall Ratio on Energy Loads in Hot Regions: A Study of Building Energy Performance

The concern regarding local responsive building design has gained more attention globally as of late. This is due to the issue of the rapid increase in energy consumption in buildings for the purpose of heating and cooling. This has become a crucial issue in educational buildings and especially in schools. The major issue in school buildings in Saudi Arabia is that they are a form of prototype school building design (PSBD). As a result, if there is any concern in the design stage and in relation to the selection of building materials, this will spread throughout the region. In addition to that, the design is repeated regardless of the climate variation within the kingdom of Saudi Arabia. This research will focus on the influence of the window to wall ratio on the energy load in various orientations and different climatic regions. The research will use the energy computer tool TAS Environmental Design Solution Limited (EDSL) to calculate the energy load as well as solar gain. During the visit to the sample schools, a globe thermometer will be used to monitor the globe temperature in the classrooms. This research introduces a framework to assist architects and engineers in selecting the proper window to wall ratio (WWR) in each direction within the same building based on adequate natural light with a minimum reliance on energy load. For ultimate WWR for energy performance and daylight, the WWR should range from 20% to 30%, depending on orientation, in order to provide the optimal daylight factor combined with building energy efficiency. This ratio can be slightly greater in higher altitude locations

Thermal and Acoustic Features of Lightweight Concrete Based on Marble Wastes and Expanded Perlite Aggregate

A large amount of industrial solid waste is generated from industrial activities worldwide. One such waste is marble waste, a waste generated from quarries which is generated in larger amount which needs attention. It is proved that this waste has a significant impact both on the people health and on the environment. Hence, research works are directed towards addressing usage of waste marble power, the aim of this experimental investigation is to study the usability of sand obtained by crushing marble waste (MWS) on the mixing of lightweight concrete based on expanded perlite aggregate (EPA). First, the mechanical, chemical, and physical properties of marble waste sand and expanded perlite aggregate were determined after which different mixtures of concrete are prepared by varying the percentage of EPA (0, 20, 40, 60, 80, and 100%), in order to find the optimum mixture focussing on obtaining best hydraulic properties. Also, in this work, the thermal and acoustic properties (thermal conductivity, thermal diffusivity, specific heat capacity and sound reduction index at different frequencies) of the tested concrete samples were investigated. Results shows that it is possible to obtain thermal and acoustic insulation lightweight concrete by using sand obtained by crushing marble wastes. Also, addition of more than 20% of EPA aggregate in concrete, develops a thermal insulating lightweight concrete which possess capacity to store heat and produce better thermal performance. Concrete blend with a percentage of more than of 20% of EPA aggregate can be placed in the category of acoustic insulation lightweight concrete. In summary, cement based on MWs and EPA provides better workability and energy saving qualities, which are economical and environmentally beneficial and may result in decreased construction budget and improve a long-term raw materials sustainability

Performance Improvement of Innovative Shear Damper Using Diagonal Stiffeners for Concentrically Braced Frame Systems

Although concentrically braced frame (CBF) systems enjoy high elastic stiffness and lateral strength, they show a low seismic energy absorption capacity. This dilemma is due to the buckling of CBFs’ diagonal members under compressive loading. To overcome the shortcoming, researchers have proposed the use of dampers to improve the behavior of CBF systems. Among the proposed dampers, the metallic shear damper is the most popular thanks to its suitable performance as well as its economic profit. The main shortcoming of the shear dampers is low stiffness. Therefore, in this article, an innovative approach is proposed to improve the behavior of the shear dampers. Subsequently, strengthening the shear damper with X-stiffeners is proposed, and its behavior is evaluated numerically and parametrically. Results indicate that by adding the X-stiffeners, the ultimate strength and elastic stiffness of the shear dampers are enhanced considerably. However, the properties of the stiffeners do not impact the stiffness in the nonlinear zone. Moreover, the behavior of the dampers is affected by parameters such as the ratio of the strength of the web plate to the flange plates, the ratio of the X-stiffeners to the flange plates, and the r factor. To consider the parameters to predict the behavior of the damper, required equations are proposed which demonstrate a good agreement with finite element results