In light of the growing need to mitigate climate change impacts, this study presents an innovative methodology combining ensemble machine learning with experimental data to accurately predict the carbon dioxide footprint (CO2-FP) of fly ash geopolymer concrete. The approach employs adaptive boosting to enhance decision tree regression (DTR) and support vector regression (SVR), resulting in a robust predictive framework. The models used key material features, including fly ash concentration, fine and coarse aggregates, superplasticizer, curing temperature, and alkali activator levels. These features were tested across three configurations (Combo-1, Combo-2, Combo-3) to determine optimal predictor combinations, with Combo-3 consistently yielding the highest predictive accuracy. The performance of the developed models was assessed based on standard metric indicators like mean absolute error (MAE), root mean square error (RMSE), Nash Sutcliffe efficiency (NSE), and correlation coefficient between the predicted and actual CO2-FP. Results demonstrated that the Adaboost-DTR model with Combo-3 configuration achieved the best performance metrics during testing (CC = 0.9665; NSE = 0.9343), outperforming both standalone and other ensemble models. The findings underscore the value of feature selection and boosting techniques in accurately estimating CO2 emissions for sustainable construction applications. This research offers remarkable benefits for policymakers and industry stakeholders aiming to optimize concrete compositions for environmental sustainability. The results support future integration with IoT systems to enable real-time CO2 monitoring in construction materials. Finally, this study establishes a foundation for developing efficient CO2-FP emission management tools.
Hydrated cement is considered one of the most complex binder systems. The development of models that suitably represent hydrated cement is still far from established due to the complexity of the hydration process, as well as the multiscale phase and different morphological properties. Therefore, this study attempts to develop a hydrated cement model using molecular-level simulation and laboratory testing. This model aimed to predict the mechanical properties of cement paste between 0.25 and 0.65 w/c ratios. In this regard, five cement paste mixtures with various w/c ratios were prepared and tested to evaluate their mechanical properties and micro-structures. Then, a novel modeling methodology using molecular dynamics (MD) simulation was carried out to develop an ingredient-based atomistic cement model. In this regard, the Dreiding force field (DFF) was used in all the simulation processes, starting from the cement clinker phases to the hydrated cement. The experimental results of cement paste mixtures revealed some useful data that was supportive of the simulations. Radial distribution function (RDF) and fractional free volume (FFV) were utilized to investigate the local atomic structure of the cement paste models. The calcium-silicate-hydrated (C–S–H) of the developed model was characterized through RDF and benchmarked to a well-known mineral analog, namely tobermorite. The developed model was computationally tested under different w/c ratios, and reliable results in terms of micro-structural matrix as well as mechanical properties were obtained. Then, the cement models incorporating different ratios of nano-silica were developed, and a good estimation of the mechanical properties was obtained. Because of the universal nature of the reported model in this research, it could be utilized to further predict the mechanical behavior and durability performance of the cement paste.
This study presents a pioneering approach that combines artificial intelligence and laser-induced breakdown spectroscopy (LIBS) to predict soil moisture co
The cement/epoxy interface is a critical component in a repair system. Normally, the adhesion properties of the epoxy coating are negatively affected by the presence of moisture or the ingress of harmful species to the interface. In this paper, the interfacial properties between the cross-linked epoxy and hydrated calcium silicate (C–S–H) using graphene (GR) and graphene oxide (GO) nanomaterials were investigated utilizing molecular dynamics (MD) simulation. Various reinforcement schemes were adopted, including adding the GR or GO layer and modifying the epoxy with GR or GO nanomaterials. In addition, three exposure systems (dry, wet, and salty) were considered. The results indicated that introducing a GO sheet at the epoxy/C–S–H interface enhanced the adhesion energy as the oxygen-containing functional groups in the GO provided better tight-binding patterns with the C–S–H surface as well as the epoxy overlay. Modifying the epoxy by GR nanosheet also increased the adhesion energy due to its suitably-oriented conformation inside the epoxy matrix. Moreover, the introduction of graphene reinforcement effectively mitigates the diffusion of moisture and chloride ions. The reported results will certainly enhance our understanding of the sustainability and durability of the epoxy-bonded concrete systems under aggressive moist and chloride environments.
A new configuration of hollow concrete blocks was fabricated in the field. Three distinct types of hollow concrete blocks were produced to assess the effectiveness of such blocks in the market. In addition, the experimentally determined thermal resistance was used to calculate the expenses, oil consumption, and CO2 emissions. Blocks made with crumb rubber failed in the ASTM C129 tests for non-load bearing compressive strength, whereas those made with the control and high-density polyethylene (HDPE) met the standard requirements. It was shown that the inclusion of rubber particles lowered the strength by 56%. The control block with the new configuration used in this investigation has a thermal conductivity of 53.4% lower than the commercial hollow blocks. While the inclusion material had a smaller impact than the arrangement of holes, HDPE thermal conductivity decreased by 6.4% compared to the control block. Likewise, the control-block wall's layout can reduce the power consumption by 53%. Moreover, the HDPE and low-density polyethylene (LDPE) blocks lowered the power consumption by 54 and 57%, respectively, saving roughly 4.26 ($/m2.year). Furthermore, the oil consumption and CO2 emissions were decreased by 56% when HDPE with 20% replacement was utilized. Reducing oil consumption as an energy source implies cleaner air and a lower carbon footprint. Therefore, it is recommended to incorporate these waste materials in the production of concrete blocks in order to reduce CO2 pollution in the world.
Self-healing geopolymer (SHG) concrete is an innovative construction material that has emerged as a promising alternative to conventional Portland cement concrete due to its exceptional mechanical properties, durability, and self-repairing ability in certain environmental conditions. However, the widespread adoption of geopolymer technologies necessitates the development of self-healing materials to prevent deterioration due to cracking. Although the literature on SHG concrete is extensive, only a few studies have investigated its properties in civil engineering applications such as paste, mortar, concrete, or composites. Common geopolymer materials include fly ash (FA), granulated blast furnace slag (GBFS), and metakaolin (MK). This review provides an overview of the current state of research on SHG and the types of self-healing agents, mechanical properties, durability, and self-healing capabilities of SHG products. The review suggests that SHG products are more resistant to environmental degradation, such as freeze–thaw cycles or chemical attacks, and have higher mechanical strength than traditional Portland cement concrete, owing to the presence of healing agents. Furthermore, SHG products exhibit excellent self-healing capabilities (able to repair cracks up to 650 μm) by forming new bonds between fractured particles when exposed to moisture, such as bonding of calcium carbonate (CaCO3) crystals precipitated by bacteria. While bacteria are the most common healing agents, new healing agents such as fibers and glass frit have been introduced; however, their healing efficiency is not as high as that of bacterial agents. This paper concludes by emphasizing the need for further research to fully understand the performance and efficiency of SHG in civil engineering applications.
Saudi Arabia is undergoing a significant rise in housing development, propelled by increasing demand for affordable housing. This demand surge posi tions compact housing as a viable sustainable approach to meet housing needs efficiently. This study employs a mixed-method approach, integrating qualitative and quantitative methods, to assess the acceptance of compact housing in Saudi Arabia. Through a comprehensive survey, it investigates public attitudes of various compact housing design features. The findings reveal a fair degree of acceptance for compact housing solutions, with an average agreement score of 3.12 out of 5. While open-plan layouts with reduced partitions and the integration of contempo rary furniture were the most preferred design features, certain elements, such as shared walls with neighbours and the merging of guest and living spaces, were less favoured. These observations provide insights into the preferences and attitudes of Saudi residents towards compact housing. The study suggests that promoting col lective housing types, such as attached, semi-attached, or apartment-style homes, may play a key role in lowering housing costs and broadening availability. How ever, achieving these goals will necessitate a comprehensive understanding of the socio-cultural preferences of residents to ensure the suitability of these housing options now and in the future.
The repair and strengthening of reinforced concrete members are very important due to several factors, including unexpected increases in load levels and/or the damaging impact of aggressive environmental conditions on structural concrete members. Many researchers have turned to using materials for the repair and strengthening of damaged structures or the construction of new concrete structural members. Ultrahigh‐performance fibre‐reinforced concrete (UHPFRC), characterized by superior structural and durability performance in aggressive environmental conditions, is one of the materials that have been considered for the repair and strengthening of concrete structural members. The repair or strengthening of concrete structures using UHPFRC needs a thorough knowledge of the behaviour of both the strengthening material and the strengthened concrete structure at service load conditions, in addition to an understanding of the design guidelines governing the use of such materials for effective repair and strengthening. In this study, the recent issues and findings regarding the use of UHPFRC as a repair or strengthening material for concrete structural members are reviewed, analysed, and discussed. In addition, recommendations were made concerning areas where future attention and research on the use of UHPFRC as a strengthening material needs to be focused if the material is to be applied in practice.
The population growth and harsh weather conditions in Saudi Arabia increase the demand for electricity due to the overwhelming usage of air-conditioning sy
The performance of insulated concrete blocks, with different industrial waste materials, was assessed for improved thermal resistance and mechanical properties. The optimal dosage of polystyrene bead (EPS), low-density polyethylene (LDPE), vermiculite (VL) and volcanic scoria (VS) was initially determined to produce concrete blocks with low thermal conductivity and acceptable compressive strength using low cement content to reduce both the CO2 emission and the cost. Thermal conductivity, compressive strength, density, absorption, cost analysis, and CO2 emission were used to assess the efficiency. The results proved that the thermal conductivity of VS, EPS, LDPE and VL blocks were reduced by about 26.1, 19.4, 17.0 and 16.7%, as compared to that of the normal block. However, the results showed that the reduction in compressive strength was 51, 47, 39, and 37% for VS, VL, LDPE, and EPS blocks, as compared to that of the control block. Further, the vermiculite block exhibited the highest water absorption of all blocks by up to about 14%. Moreover, the results of cost analysis proved that the EPS and VS are the cheapest insulated blocks, as compared to other insulated blocks. Besides, the results support the recommendation to use VS-insulated block because of its lowest thermal conductivity and it satisfied the requirements of compressive strength as non-load bearing walls. It is found that the best wall (VS) can improve the thermal resistance by about 279% when compared to the conventional concrete blocks. This improvement could reduce the cost of energy consumption from 349.3 to 99.4 $/m2 (about 3.5 times of reduction) based on net present value (NPV) over 50 years. The VS-wall could minimize the CO2 by about 3.71 times over the conventional concrete block and about 1.35 times over the control wall. This work has achieved the following dual benefits: conversion of waste polymers into useful materials to produce cheap and sustainable constructional material as well as saving the energy and thus the environment.
Shear failure in RC beams can lead to sudden and catastrophic collapse, posing significant risks to the occupants and the structure itself. The computation
Self-sensing concrete (SSC) has emerged as a promising material for Structural Health Monitoring (SHM) due to its ability to detect internal strain and damage through its intrinsic electrical properties. This study investigates the combined influence of saturation and alternating current (AC) frequency on the impedance and piezoresistive behavior of SSC. The specimens were prepared using conductive steel fibers (CSF). Impedance and stress-resistivity measurements were conducted across a range of AC frequencies. Results indicate that drying significantly affects both impedance magnitude and phase angle, with more pronounced effects observed at higher frequencies. Additionally, the piezoresistive response of SSC exhibited strong frequency dependence. These findings highlight the importance of accounting for environmental factors and input in the design and implementation of SSC-based SHM systems. The study provides data analysis for optimizing measurement protocols to enhance the sensitivity and accuracy of self-sensing materials in real applications.
Heat transfer has become of great importance due to the excessive energy consumption, which is greatly affected by the amount of thermal flow to the inner surfaces of the building envelope (walls and roof).In this investigation, thermal analysis of a room (slab, walls, columns and plaster) was conducted with two types of slab (solid slab and one-way-ribbed slab) using finite element model (FEM) with ABAQUS software to investigate the effect of slab type and plastering on the overall inner surface temperature of the room.Plastering with thickness of 1 cm was used from both sides of the room envelopes.Results of the FEM indicate that the ribbed slab was more thermally efficient than the solid one by about 19% and 17% for plastered and non-plastered slabs, respectively.For the overall inner temperature of the room, the room with ribbed slab was more thermally resistant than that with the solid one by approximately 38%.The effect of plaster with ribbed slab had a little increment on the thermal resistance compared to the solid one by about 0.55°C; while the effect was negligible in the case of walls.The effect of mortar on temperature increment of the wall was 0.56°C.For the room with solid slab, the inner surface temperature for one wall was almost the same for both plastered and non-plastered walls, while it was 0.73°C for the room with ribbed slab because the beams (30 cm thickness) increased the heat flow to the upper face of the wall.The heat flow from the ribbed slab to the columns was much higher than the solid one by about 3.11%.However, the room with ribbed slab was more comfortable from thermal point of view as compared to the room with solid slab.
