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The purpose of this paper is to highlight the sustainability benefits of using demolition and industrial wastes as a replacement for aggregates and cement in traditional concrete mixes.

Crushed concrete from demolition sites served as a replacement for fine and coarse aggregate in some of the mixes at various ratios. In addition, ground granulated blast furnace slag, metakaolin, silica fume, and fly ash each served as a cement replacement for cement content in the mixes tested in this research at various rates. Compression strength tests, permeability, and thermal expansion tests were performed on various mixes to compare their performance to that of traditional mixes with natural aggregate, and with no cement replacement.

The compressive strength results indicated the suitability of using such demolition wastes as replacements in producing green concrete (GC) without hindering its mechanical characteristics significantly. In addition, the results indicated an enhancement in the mechanical characteristics of GC when replacing cement with pozzolanic industrial wastes and byproducts.

The research assesses the utilization of sustainable GC using recycled waste aggregate and byproducts.

This study aims to present the results of an experimental evaluation of low (M30), mid (M40) and high (M50) grade self-compacting concrete (SCC) with three nominal maximum aggregate sizes (NMAS), namely, 20 mm, 16 mm and 12.5 mm, with Bailey gradation (BG) in comparison with Indian standard gradation (ISG).

This study was conducted in a laboratory by testing the characteristics of fresh and hardened properties of self-compacting concrete.

Rheological and mechanical properties of SCC were evaluated in detail and according to the results, a concrete sample containing lower NMAS with BG demonstrated improvement in modulus of elasticity and compressive strength, while improving the rheological properties as well. Meanwhile, SCC demonstrated poor performance in split tensile and flexural strengths with lower NMAS gradations and a direct correlation was evident as the increase in NMAS caused an increase in the strength and vice-versa.

Upon comparison of BG with ISG, it was revealed that BG mixes succeeded to demonstrate superior performance. From the material optimization, rheological and mechanical performance study, it is recommended that BG with NMAS 16 mm can be used for conventional SCC.

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.

Fracture properties of concrete are mainly influenced by specimen shape, size and type of testing method. The study aims to identify the characteristic divergence in fracture – evaluating testing methods, i.e. three-point bend test and wedge splitting test for fibrous self-compacting concrete.

A total of nine mixes with three different coarse aggregate sizes (20, 16 and 12.5mm) and three coarse to fine aggregate quantities (40–60, 45–55 and 50–50) were considered to examine the influence of materials on fracture parameters of fibrous self-compacting concrete. For three-point bend test, size effect method was considered to analyze the fracture properties.

The experimental investigation revealed that fracture energy calculated from wedge splitting test was reasonably on higher side for maximum coarse aggregate-based specimens for all coarse to fine aggregate quantities, while for the size effect method, fracture energy value was maximum for least coarse aggregate sized specimens.

The fracture properties of fibrous self-compacting concrete obtained from wedge splitting test method was higher than the size effect method. This is due to the consideration of only peak load for determining the fracture properties in size effect method analysis.

The purpose of this work is to improve the air entrainment capacity of a concrete by using fine mineral admixtures such as fly ash (FA) and silica fume (SF) as cement substitute, and coal bottom ash (CBA) as fine aggregate substitute. Air entrainment capacity has been studied indirectly as a measure of heat resistance of concrete. Literature has suggested that mineral admixtures improve the air absorption in the paste component of the concrete, on the one hand, whereas they perform pore and grain size refinement, on the other, thereby reducing the air entrainment. CBA, which being porous, creates the possibility of air adsorption by the aggregate component. Therefore, the study finds out whether a double benefit of adding both of these materials will be achieved, or CBA will try to improve the deficiency in the air entrainment created by the mineral admixtures.

Air-entrained concrete (AEC) mixes were constituted in three groups. First group represents mixes with natural fine aggregates only, and second with 25% fine aggregates substituted by CBA. Progressively, the third group has 50% fine aggregates substituted with CBA. In all the three groups, cement was substituted with FA and SF @ 0%, 20% and 40%, and 0%, 5% and 10%, respectively, thereby creating four binary and four ternary mixes corresponding to each group. Compressive and flexural strength tests were conducted at 28 days on the concrete mixes pre and post high-temperature heat treatment, i.e. 100°C, 200°C and 400°C, respectively. This study also examines the microstructure characteristics of AEC after 14 days of curing via X-ray diffraction. Sorptivity test was also conducted to estimate the capillary and air-entrained voids in concrete.

It was found that a concrete mix containing 20% FA and 10% SF along with 50% CBA could give similar post-heated strength to a normal (without mineral admixtures) AEC. In AECs where only CBA is present and cement paste is not substituted, both of the pre- and post-heated strengths of concrete reduce. Also, some mixtures containing large amounts of mineral admixtures in concrete with nil CBA show a high reduction in post-heated strength though they show good pre-heated strength. Therefore, mineral admixtures and CBA complement each other in improving the post-heated strength. Air pore structure found from sorptivity test also verifies these results.

AEC is very helpful for insulation of buildings during summer season by absorbing heat waves. AEC containing FA and CBA reduces carbon footprint because of substitution of cement and it also helps to conserve natural resources by the use of CBA in place of fine aggregates.

This paper aims to discuss the evaluation of the compressive and splitting tensile strength of concrete mixes containing different proportions of up to 20 per cent glass aggregate. Portions of sand in concretes with and without admixtures were replaced with measurements of glass aggregates.

“Glascrete” is a term used for concrete in which crushed glass is used as a substitute for all or part of the aggregates. Glass can be recycled many times without changing its properties, making it an ideal material in concrete. Overall, 144 cubes and 144 cylinders of glascretes were prepared with different admixtures and subjected to compressive and splitting tensile strength test.

A comparison with a 21-day control mix indicated that glass aggregates are replacing sand in concrete ranging from 5 to 20 per cent by volume, resulting in 3.8-10.6 per cent and 3.9-16.4 per cent fall in compressive and tensile strength, respectively. However, the use of mineral admixture improved the properties of the mixes at 3, 7, 14 and 21 days.

Cities worldwide are congested, and even those with the best waste-management system would have issues with waste disposal after the year 2030. Consequently, waste management is a current issue for cities all over the world.

This study aims to evaluate the physical properties of mortar mixes that contain different volumes of waste glass as substitutes for fine aggregate with or without additives. Mineral additives are used to improve the mechanical properties of glascrete mixes in addition to its chemical resistance by absorbing the OH⁻ ions responsible for the possible alkali-silica reaction (ASR). It also reduces the adverse effects of mix-dimensional stability. Water-reducing admixtures are used to reduce the impact of the ASR by minimizing the amount of moisture in concrete, in effect decreasing the possible expansion of any produced gel. In this research, compressive and splitting tensile strength of concrete mortar containing waste glass of limited substitutions is evaluated.

The purpose of this paper is to investigate the potential use of construction and demolition waste materials (C&DWM) as an alternative for natural fine aggregates (NFA), in view to solve the disposal problems caused due to landfills. In addition, to evaluate its suitability as a sustainable material, mechanical and durability properties have been performed on different proportions of concrete blending and the results recorded were compared with the reference concrete values.

In this research, the NFA were replaced at the proportion of 25%, 50%, 75% and 100% of C&DWM with a constant slump range of 130 mm–150 mm. This parameter will assess the consistency of the fresh concrete during transportation process. The characteristics of the end product was evaluated through various tests conducted on hardened concrete samples, namely, compressive strength, flexural strength, depth of penetration of water under pressure, rapid chloride penetration test, carbonation test and ultrasonic pulse velocity (UPV) test. All results recorded were compared with the reference concrete values.

The results demonstrated that the use of C&DWM in concrete portrayed prospective characteristics that could eventually change the concept of sustainable concrete. It was noted that the compressive and flexural strength decreased with the addition of C&DWM, but nevertheless, a continuous increase in strength was observed with an increase in curing period. Moreover, the increase in rapid chloride penetration and decrease in UPV over time period suggested that the concrete structure has improved in terms of compactness, thus giving rise to a less permeable concrete. The mechanical tests showed little discrepancies in the final results when compared to reference concrete. Therefore, it is opined that C&DWM can be used effectively in concrete.

This study explores the possible utilisation of C&DWM as a suitable surrogative materials in concrete in a practical perspective, where the slump parameter will be kept constant throughout the experimental process. Moreover, research on this method is very limited and is yet to be elaborated in-depth. This approach will encourage the use of C&DWM in the construction sector and in the same time minimise the disposal problems caused due to in landfills.

This study aims to investigate the compressive strength of concretes incorporating Linz-Donawitz slag (LD slag) as partial replacement for natural fine and coarse aggregates and compare them with traditional concrete.

The natural fine and coarse aggregates were replaced by weight simultaneously up to 100% with LD slag aggregates at an incremental increase of 20%. Concrete of grades M20, M25, M30, M35 and M40 were cast, cured and tested with standard cube specimens to study the density and compressive strength of reference and LD slag aggregate concretes (LDSACs). The concrete specimens were exposed to elevated temperatures, i.e. 100 to 900 °C at an equal interval of 100 °C and tested to study the variation in density and residual compressive strength.

The results from the experiments reveal that the LDSAC yields a higher density than that of the reference concrete and also undergo less density variation when exposed to elevated temperatures. In addition, the residual compressive strength of LDSAC specimens was significantly higher than that of the reference concrete.

LD slag is believed to be stronger and more durable than locally available limestone aggregates or blast furnace slag. Moreover, it is necessary to study its strength and other properties to determine whether it can be successfully used as an aggregate in concrete universally.

Use of LD slag as aggregates in concrete will convert LD slag into a value added product and as an alternative to the existing natural aggregates which will help in maintaining ecological balance and save valuable lands.

The economically weaker section of the society may now use LDSAC as waste utilization will bring down the overall cost and hence it will benefit people on large scale.

Use of LD slag as aggregate in concrete can help find an alternative to the existing natural aggregates which will save the ecosystem and at the same time help in reducing the industrial waste on a large scale.

This study aims to discuss the results of fresh properties and compressive strength of self-compacting concrete using ingredients added red brick powder as a fine aggregate substitute. The results of the study were compared with the properties of fresh properties and compressive strength with ingredients added by rice husk ash, which is also a fine aggregate substitute. In addition, the initial compressive strength of each of these variations was also examined to accelerate the completion time of construction projects using self-compacting concrete.

This research was conducted in a laboratory by testing the characteristics of fresh and hardened properties of self-compacting concrete.

Fresh properties testing is carried out in the form of V-funnel, flow table, J-ring and L-box where all specimens produce quite varied flow rates. Compressive strength was estimated at ages 3, 7, 14 and 28 days with cylindrical specimens with a diameter of 150 mm and a height of 300 mm. The variation of fine aggregate substitutes used is 20, 40 and 60 per cent.

From the results of the compressive strength, it can be concluded that the added material is categorized as self-compacting concrete with high initial compressive strength, while at 28 days, the compressive strength test results are categorized as high-strength self-compacting concrete.

Utilization of sustainable materials is a global demand in the construction industry. Hence, this study aims to integrate waste management and artificial intelligence by developing an artificial neural network (ANN) model to predict the compressive strength of green concrete. The proposed model allows the use of recycled coarse aggregate (RCA), recycled fine aggregate (RFA) and fly ash (FA) as partial replacements of concrete constituents.

The model is constructed, trained and validated using python through a set of experimental data collected from the literature. The model’s architecture comprises an input layer containing seven neurons representing concrete constituents and two neurons as the output layer to represent the 7- and 28-days compressive strength. The model showed high performance through multiple metrics, including mean squared error (MSE) of 2.41 and 2.00 for training and testing data sets, respectively.

Results showed that cement replacement with 10% FA causes a slight reduction up to 9% in the compressive strength, especially at early ages. Moreover, a decrease of nearly 40% in the 28-days compressive strength was noticed when replacing fine aggregate with 25% RFA.

The research is limited to normal compressive strength of green concrete with a range of 25 to 40 MPa.

The developed model is designed in a flexible and user-friendly manner to be able to contribute to the sustainable development of the construction industry by saving time, effort and cost consumed in the experimental testing of materials.

Green concrete containing wastes can solve several environmental problems, such as waste disposal problems, depletion of natural resources and energy consumption.

This research proposes a machine learning prediction model using the Python programming language to estimate the compressive strength of a green concrete mix that includes construction and demolition waste and FA. The ANN model is used to create three guidance charts through a parametric study to obtain the compressive strength of green concrete using RCA, RFA and FA replacements.