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The purpose of this paper is to study the effect of nano alumina (Al₂O₃) on the properties of fresh concrete, hardened concrete and microstructure of concrete incorporated with high range water reducer (HRWR). This initiative was taken to improve characteristic properties of concrete using nano alumina because nano alumina can be easily be manufactured from a scrap of industrial aluminum products, so its incorporation in concrete will not only reduce industrial aluminum waste but will also change the morphology of concrete at the microstructural level.

To accomplish the objectives of the research, four different concrete mixes with the constant water–cement ratio (W/C) and superplasticizer (SP) content 0.4 and 0.6% by weight of cement, respectively, were prepared, whereas nano alumina content was altered by 0.3% and 0.4% by weight of cement. Fresh property of concrete was analyzed by using slump cone test, whereas hardened properties of concrete were analyzed through compression test and flexural strength test. The interaction of nano alumina with concrete composite was evaluated using an X-ray diffraction test.

It was observed that 0.6% superplasticizer by weight of cement increased workability by 22% but with the addition of 0.3%, nano alumina by weight of cement workability decreased by 31%. Compressive strength increased by 4.88% with the addition of 0.6% superplasticizer but with the addition of 0.3% nano alumina by weight of cement compressive strength increased by 18.60%. Also, flexural strength increased by 1.21% with the addition of 0.6% superplasticizer by weight of cement but with the addition of 0.3% nano alumina by weight of cement flexural strength increased by 8.76%. With the addition of superplasticizer, alite and belite phases remained un-hydrated but with the addition of nano alumina alite phase was hydrated while belite phase was un-hydrated. The size of belite crystals in mixes having nano alumina was less than that of mix having 0.6% superplasticizer. Also with the addition of nano alumina, a calcium aluminum silicate phase was formed which was responsible for the increment of strength in mixes having nano alumina.

Incorporation nano alumina (Al₂O₃) in concrete will not only reduce industrial aluminum waste but will also reduce CO₂ emission. Nano alumina (Al₂O₃) also changes morphology of concrete at micro structural level.

This study aims to investigate the properties of mortar made from a bottom ash substitute as a sustainable construction material. It is believed that the use of cement in concrete construction contributes to the release of carbon dioxide into the atmosphere, which has been a consistent increase in recent years. The utilization of bottom ash waste is expected to reduce pollution associated with cement production.

Bottom ash is used as replacement materials for cement and fine aggregate in the manufacture of mortar. Bottom ash substituted for cement of 10%, 20% and 30% of the total weight of the binder, whereas bottom ash substituted for the fine aggregate of 30%, 40% and 50% of the total weight of the sand. Binder properties were determined using scanning electron microscopy and energy dispersive X-ray. Meanwhile, the fresh properties (slump flow) and hardened properties were determined (compressive strength and mass density). In the hardened properties test, two types of curing were used: water and sealed curing.

The compressive strength of mortar decreased as the amount of bottom ash as cement replacement. However, the compressive strength increased when bottom ash was used as aggregate replacement. Additionally, bottom ash was sufficient as a substitute for fine aggregate than as a substitute for cement.

This research presents test results that are more straightforward to apply in the construction site.

This study aims on a broad review of Concrete's Rheological Properties. The Concrete is a commonly used engineering material because of its exquisite mechanical interpretation, but the addition of constituent amounts has significant effects on the concrete’s fresh properties. The workability of the concrete mixture is a short-term property, but it is anticipated to affect the concrete’s long-term property.

In this review, the concrete and workability definition; concrete’s rheology models like Bingham model, thixotropy model, H-B model and modified Bingham model; obtained rheological parameters of concrete; the effect of constituent’s rheological properties, which includes cement and aggregates; and the concrete’s rheological properties such as consistency, mobility, compatibility, workability and stability were studied in detail.

Also, this review study has detailed the constituents and concrete’s rheological properties effects. Moreover, it exhibits the relationship between yield stress and plastic viscosity in concrete’s rheological behavior. Hence, several methods have been reviewed, and performance has been noted. In that, the abrasion resistance concrete has attained the maximum compressive strength of 73.6 Mpa; the thixotropy approach has gained the lowest plastic viscosity at 22 Pa.s; and the model coaxial cylinder has recorded the lowest stress rate at 8 Pa.

This paper especially describes the possible strategies to constrain improper prediction of concrete’s rheological properties that make the workability and rheological behavior prediction simpler and more accurate. From this, future guidelines can afford for prediction of concrete rheological behavior by implementing novel enhancing numerical techniques and exploring the finest process to evaluate the workability.

The compressive strength of concrete depends on many interdependent parameters; its exact prediction is not that simple because of complex processes involved in strength development. This study aims to predict the compressive strength of normal concrete and high-performance concrete using four datasets.

In this paper, five established individual Machine Learning (ML) regression models have been compared: Decision Regression Tree, Random Forest Regression, Lasso Regression, Ridge Regression and Multiple-Linear regression. Four datasets were studied, two of which are previous research datasets, and two datasets are from the sophisticated lab using five established individual ML regression models.

The five statistical indicators like coefficient of determination (R²), mean absolute error, root mean squared error, Nash–Sutcliffe efficiency and mean absolute percentage error have been used to compare the performance of the models. The models are further compared using statistical indicators with previous studies. Lastly, to understand the variable effect of the predictor, the sensitivity and parametric analysis were carried out to find the performance of the variable.

The findings of this paper will allow readers to understand the factors involved in identifying the machine learning models and concrete datasets. In so doing, we hope that this research advances the toolset needed to predict compressive strength.

Concrete, the second most used material in the world, surpassed only by water, relies on a vast amount of cement. The process of cement production emits substantial amounts of carbon dioxide (CO₂). Consequently, it is crucial to search for cement alternatives. Geopolymer concrete (GC) uses industrial by-product material instead of traditional cement, which not only reduces CO₂ emissions but also enhances concrete durability. On the other hand, the disposal of concrete waste in the landfills represents a significant environmental challenge, emphasising the urgent need for sustainable solutions. This study aimed to investigate waste concrete's best form and rate as the alternative aggregates in self-compacting and ambient-cured GC to preserve natural resources, reduce construction and demolition waste and decrease pertinent CO₂ emissions. The binding material employed in this research encompasses fly ash, slag, micro fly ash and anhydrous sodium metasilicate as an alkali activator. It also introduces the best treatment method to improve the recycled concrete aggregate (RCA) quality.

A total of25%, 50% and 100% of coarse aggregates are replaced with RCAs to cast self-compacting geopolymer concrete (SCGC) and assess the impact of RCA on the fresh, hardened and water absorption properties of the ambient-cured GC. Geopolymer slurry was used for coating RCAs and the authors examined the effect of one-day and seven-day cured coated RCA. The mechanical properties (compressive strength, splitting tensile strength and modulus of elasticity), rheological properties (slump flow, T500 and J-ring) and total water absorption of RCA-based SCGC were studied. The microstructural and chemical compositions of the concrete mixes were studied by the methods of energy dispersive X-Ray and scanning electron microscopy.

It is evident from the test observations that 100% replacement of natural aggregate with coated RCA using geopolymer slurry containing fly ash, slag, micro fly ash and anhydrous sodium metasilicate cured for one day before mixing enhances the concrete's quality and complies with the flowability requirements. Assessment is based on the fresh and hardened properties of the SCGC with various RCA contents and coating periods. The fresh properties of the mix with a seven-day curing time for coated RCA did not meet the requirements for self-compacting concrete, while this mix demonstrated better compressive strength (31.61 MPa) and modulus of elasticity (15.39 GPa) compared to 29.36 MPa and 9.8 GPa, respectively, for the mix with one-day cured coated RCA. However, incorporating one-day-cured coated RCA in SCGC demonstrated better splitting tensile strength (2.32 MPa) and water absorption (15.16%).

A potential limitation of this study on SCGC with coated RCAs is the focus on the short-term behaviour of this concrete. This limited time frame may not meet the long-term requirements for ensuring the sustained durability of the structures throughout their service life.

This paper highlights the treatment technique of coating RCA with geopolymer slurry for casting SCGC.

Concrete-filled double skin steel tubes (CFDST) columns are taken more attention due to their ability to withstand high structural loads in structures such as high-rise buildings, bridges' piers, offshore and marine structures. This paper is intended to improve the CFDST column's capacity without the need to increase the column's size to maintain its lightweight by filling it with self-compacted concrete (SCC) containing nanoclay (NC).

First, experimental investigation is conducted to select the optimal NC percentage that improves the mechanical properties. Different mixing method, mixture ingredients, cement content, and NC percentage are considered. Then, slender and short CFDST columns are tested for axial capacity to investigate the effect of adding the optimum NC percentage on column's capacity and failure mode.

The test results show that adding 3% NC by cement weight using dry mixing method to SCC is the optimum ratio. It is concluded that adding 3% NC by cement weight increased the CFDST column's capacity, especially the specimens with higher slenderness ratio. Moreover, it is concluded that more specimens should be tested under various geometric and reinforcement details.

Recently, CFDST tube columns solve many structural and architectural problems that engineers have encountered in traditional systems. Therefore, more studies are required to design high-performance columns capable of carrying complex loads with high efficiency since the traditional design could not achieve the required performance. Since concrete contributes to a large portion in the axial capacity of the CFDST columns, it is proposed to improve the CFDST column's capacity without the need to increase the column's size to maintain its lightweight by filling it with (SCC containing NC. Previous research has affirmed the effectiveness of employing nanoclay in the concrete's workability, durability, microstructures, and mechanical properties.

This paper aims to express a mathematical model that predicts the effect of mineral additives on the physical–mechanical properties of high-performance sand concrete (HPSC), using SAS's JMP7 statistical analysis software.

A mixture design modeling approach is applied to sand concrete (SC) for optimizing mixtures without being obliged to do a lot of experiments, where the cement is partially replaced with two mineral additives silica fume (SF) and blast furnace slag (BFS) in proportions as high as 20% of the mass. A total of 15 mixtures of sand concrete is prepared in the laboratory using this analytical technique in combinations with binary and ternary systems to estimate the workability and the compressive strength (CS) of sand concrete at 7 and 28 days.

The results obtained showed that the use of derived models based on the experimental design approach greatly assisted in understanding the interactions between the various parameters of the studied mixtures; the mathematical models present excellent correlation coefficients (R² = 0.96 for CS7 days, R² = 0.93 for CS28 days and R² = 0.95 for slump) for all studied responses. Moreover, it was also found that the inclusion of additives (SF and BFS) in binary mixture SC12 and ternary mixtures SC8 leads to a significant improvement in mechanical strength compared to reference sand concrete SC15. These results give the possibility to obtain a formulation of HPSC.

This paper shows the possibility of manufacturing high-performance sand-concrete with good compressive strength; the developed mathematical model by using SAS's JMP7 statistical analysis software allowed us to reach a strength compression value of about 60 MPa, in 28 days, by replacing 10% of the cement weight with silica fume. Furthermore, with partial replacement of the cement weight (15%) with two additions such as silica fume (10%) and blast furnace slag (5%), a 58 MPa of compressive strength can be achieved, without overlooking the fact that this can be a key economic and environmental alternative.

This study aims to practically determine the optimum proportion of aggregates to attain the desired strength of geopolymer concrete (GPC) and then compare the results using established analytical particle packing methods. The investigation further aims to assess the influence of various amounts of recycled aggregate (RA) on properties of low-calcium fly ash-based GPC of grade M25.

Fine and coarse aggregates were blended in various proportions and the proportion yielding maximum packing density was selected as the optimum proportion and they were compared with analytical models, such as Modified Toufar Model (MTM) and J. D. Dewar Model. RAs for this study were produced in laboratory and they were used in various amounts, namely, 0%, 50% and 100%. 12M NaOH solution was mixed with Na₂SiO₃ in the ratio of 1:2. The curing of concrete was done at the temperatures of 60° and 90 °C for 24, 48 and 72h.

The experimentally obtained optimum proportion of coarse to fine aggregate was 60:40 for all amounts of RA. Meanwhile, MTM and Dewar Model resulted in coarse aggregate to fine aggregates as 40:60, 45:55, 55:45 and 55:45, 35:65, 60:40, respectively, for 0% 100% and 50% RAs. The compressive strength of GPC elevated with the increase in curing regime. In addition, the ultrasonic pulse velocity also displayed a similar trend as that of strength.

The GPC with 50% RAs may be considered for use, as it exhibited superior properties compared to GPC with 100% RAs and was comparable to GPC with natural aggregates. Furthermore, compressive strength is correlated with split tensile strength and ultrasonic pulse velocity.

To contribute to the identification of the parameters influencing the behavior of textile-reinforced concrete (TRC), the purpose of this paper is to investigate the flexural behavior of TRC-based plates under four-point bending notably designed in the context of sustainable development and the substitution of mortar components with natural and abundant materials.

An extensive experimental campaign was focused about two main parameters. The first one emphases the textile reinforcements, such as the number of layers, the nature and the textile mesh size. In the second step, the composition of the mortar matrix was explored through the use of dune sand as a substitute of the river one.

Test results in terms of load-displacement response and failure patterns were highlighted, discussed and confronted to literature ones. As key findings, an increase of the load-bearing capacity and ductility, comparable to the use of an industrially produced second textile layer was recorded with the use of dune sand in the mortar mix design. The designed ecofriendly samples with economic concerns denote the significance of obtained outcomes in this research study.

The novelty of the present work was to valorize the use of natural dune sand to design new TRC samples to respond to the environmental and economical requirements. The obtained values provide an improved textiles–matrix interface performance compared to classical TRC samples issued from the literature.

Cement can be replaced to reduce the energy consumption and the environmental impact of cement. Also, foamed concrete can be used structurally in residential buildings to reduce weight and improve thermal insulation. To achieve these two goals, this paper aims to investigate the effect of basalt powder as a partial replacement of either cement or sand.

This paper investigates the effect of basalt powder as a partial replacement of either cement or sand on the mechanical properties of foamed concrete used to cast slabs. First, mechanical properties of foamed concrete are tested with and without replacement of basalt. Then, six slabs of different thicknesses and mixes are investigated. The thicknesses considered are 150- and 200-mm slabs. The three mixes used to construct these slabs are foamed concrete with no basalt powder, foamed concrete with replacement of 20% of cement by basalt powder and foamed concrete with replacement of 20% of sand by basalt powder. The flexural behavior of these slabs is investigated.

All the slabs failed in the commonly intended flexural mode. The results show that the basalt powder acted as a strong filler material in the foamed concrete mix based on mechanical properties and flexural behavior. The proposed foamed concrete slabs can be used structurally in residential buildings.

A natural waste material that can be used to promote energy efficiency and reduce emission is basalt. In this paper, basalt powder is suggested to be used due to its chemical composition that is similar to cement. Also, basalt powder is low in cost as it is waste, while basalt aggregate is prepared, and it is only used as filler in paved roads. Accordingly, basalt is partially used instead of cement to reduce the emission of carbon dioxide that results from the cement manufacturing. Also, it is used as a partial alternative to sand which can be considered as a new stronger source as filling material used in the production of concrete.