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Concrete is a building material widely used for the infrastructural development. Cement is the binding material used for the development of concrete. It is the primary cause of CO₂ emission globally. The purpose of this study is to develop sustainable concrete material to satisfy the present need of construction sector. Geopolymer concrete (GPC) is a sustainable concrete developed without the use of cement. Therefore, investigations are being conducted to replace the cement by 100% with high calcium fly ash (FA) as binding material.

High calcium FA is used as cementitious binder, sodium hydroxide (NaOH) and sodium silicates (Na₂SiO₃) are used as alkaline liquids for developing the GPC. Mix proportions with different NaOH molarities of 4, 6, 8 and 10 M are considered to attain the appropriate mix. The method of curing adopted is ambient and oven curing. Workability, compressive strength and microstructure characteristics of GPC are analysed and presented.

An increase of NaOH in the mix decreases the workability. Compressive strength of 29 MPa is obtained for Mix-I with 8 M under ambient curing. A polynomial relationship is obtained to predict the compressive strength of GPC. Scanning electron microscope analysis is used to confirm the geo-polymerisation process in the microstructure of concrete.

This research work focuses on finding some alternative cementitious material for concrete that can replace ordinary portland cement (OPC) to overcome the CO₂ emission owing to the utilisation of cement in the construction industry. An attempt has been made to use the waste material (high calcium FA) from thermal power plant for the production of GPC. GPC concrete is the novel building material and alternative to conventional concrete. It is the ecofriendly product contributing towards the improvement of the circular economy in the construction industry. There are several factors that affect the property of GPC such as type of binder material, molarity of activator solution and curing condition. The novelty of this work lies in the approach of using locally available high calcium FA along with manufactured sand for the development of GPC. As this approach is rarely investigated, to prove the attainment of compressive strength of GPC with high calcium FA, an attempt has been made during the present investigation. Other influencing parameter which affects the strength gain has also been analysed in this paper.

This study aims to propose a technique that establishes a mathematical relationship between width and time, and utilizes a derivative method to determine the initial printable time (tint) for mortar suitable for 3D printing. The study conducted experimental tests on the tint, layer strain, and the relationship between filament width and time. These tests involved plain mortar and mortar reinforced with micro-fibers at varying volume fractions. The tint was determined analytically using the derivative method.

This study introduces a technique to accurately determine the initial printable time (tint) and width/height of printed cement mortar. Precise tint determination is essential for ensuring proper filament printing timing and eliminating the need for trial and error.

Results show that the proposed technique accurately determines the tint, as evidenced by the resemblance between expected and actual initial widths. Fiber-reinforced mortar (FRM) has a smaller tint than plain mortar, which decreases with an increasing fiber content. Additionally, FRM displays smaller layer strains compared to plain mortar.

Results show that the proposed technique accurately determines the tint, as evidenced by the resemblance between expected and actual initial widths. FRM exhibits smaller tint and displays smaller layer strains than plain mortar.

This study introduces a novel technique that uses a mathematical relationship to determine the tint and height of cement mortar printing.

While circular economy (CE) is fast becoming a political and economic agenda for global urban development, there are still substantial knowledge gaps in possible strategies to speed up such transition, especially in the construction industry. This study analyses literature surrounding CE to unpack current trends possible future research directions to foster CE implementation in the construction industry.

The study undertakes a systematic review of CE literature published between 1990 and 2019. It adopts a five-stage procedure as a methodological approach for the review: formulation of the research question(s), locating and identifying relevant studies, selection and evaluation of studies, analysis or synthesis and results reporting.

The findings on CE research in the construction industry show extensive focus on resource use and waste management. There are limited investigations in other areas of construction such as supply chain integration, building designs, policy, energy efficiency, land use, offsite manufacturing, whole life costing, and risk, cost reduction, cost management, health and safety management. The study findings provide evidence that current CE practice fails to incorporate other areas that would facilitate the network of true circular construction industry.

This research provides a comprehensive overview of research efforts on CE in the construction context, identifying areas of extensive and limited coverage over three decades. Besides, it identifies possible pathways for future research directions on CE implementation, towards the accelerated transition to a true circular construction industry for the benefit of funding bodies and researchers.

Buildings respond differently to microbial invasion depending on the design, type of construction materials and finishes used and extent of exposure to climatic factors. However, in the hot-humid tropical environment of Nigeria, much is not known about how buildings with different types of façade finishes or claddings are liable to microbial decay. The purpose of this research is to investigate the susceptibility of buildings with different types of façade finishes to microbial decay in Enugu metropolis, southeast Nigeria.

A survey involving physical observation of purposively selected 383 buildings and questionnaire administration to their owners was carried out in the study area. The data were subjected to descriptive and logistic regression analyses.

Most of the 383 buildings sampled were less than 41 year and 47% of them had painted façade finishes followed by 25.1% with cementitious finishes. Around 63.4% of the buildings had their façade finishes or claddings colonised by microbes. Older buildings of 15 years and above and those with cementitious materials and paints as their predominant façade finishes were more likely to experience microbial decay than newer ones and those having refractory bricks, ceramic tiles, aluminium composite materials and plastics/polymers as their predominant façade finishes or claddings.

The study identifies the categories of buildings that are likely to be more susceptible to microbial decay; and thus contributes to research on how to slow down the rate of biodeterioration of building façade finishes or claddings in the hot-humid tropical environments.

This is the first study on the susceptibility of buildings with different types of façade finishes or claddings to microbial decay in the hot-humid tropical environment of Enugu metropolis, southeast Nigeria. It also provides a clue on the age at which buildings become more vulnerable to microbial decay in the study area.

The United Nations has demonstrated a commitment to preserving the ecosystem through its 2030 sustainable development goals agenda. One crucial objective of these goals is to promote a healthy ecosystem and discourage practices that harm it. Building materials production significantly contributes to the emissions of greenhouse gases. This poses a threat to the ecosystem and prompts a growing demand for sustainable building materials (SBMs). The purpose of this study is to investigate SBMs to determine their utilization in construction operations and the potential impact their application could have on construction productivity.

A systematic review of the existing literature in the field of SBMs was conducted for the study. The search strings used were “sustainable” AND (“building” OR “construction”) AND “materials” AND “productivity”. A total of 146 articles were obtained from the Scopus database and reviewed.

Bio-based, cementitious and phase change materials were the main categories of SBMs. Materials in these categories have the potential to substantially contribute to sustainability in the construction sector. However, challenges such as availability, cost, expertise, awareness, social acceptance and resistance to innovation must be addressed to promote the increased utilization of SBMs and enhance construction productivity.

Many studies have explored SBMs, but there is a dearth of studies that address productivity in the context of SBMs, which leaves a gap in understanding. This study addresses this gap by drawing on existing studies to determine the potential implications that using SBMs could have on construction productivity.

Fire can severely affect concrete structures and with knowledge of the properties of materials, the damage can be assessed. Aggregate, cement matrix and their interaction are the most important components that affect concrete behaviour at high temperatures. The effect of incorporating recycled concrete aggregate or cementitious materials, namely, cement type and pulverized fly ash, are reviewed to provide a better understanding of their involvement in fire resistance.

More investigation research is needed to understand the fire resistance of such sustainable concrete that was already constructed. The present study illustrates the effect of using recycled concrete aggregate and cementitious materials on the fire resistance of concrete. To do so, a literature review was conducted and relevant data were collected and presented in a simple form. The author's selected research findings, which are related to the presents study, are also presented and discussed.

Recycled concrete aggregate enhances the concrete behaviour at high temperatures when it substitutes the natural aggregate by reasonable substitution (more than 25–30%). It also almost eliminates the possibility of spalling. Moreover, utilizing both supplementary cementitious materials with recycled concrete aggregate can improve the fire resistance of concrete. The incorporation of pulverized fly ash and slag in Portland cement or blended cement can generally keep the mechanical properties of concrete at a higher level after heating to a high temperature.

Recycled concrete aggregate enhances the concrete behaviour at high temperatures when it substitutes the natural aggregate by reasonable substitution (more than 25–30%). It also almost eliminates the possibility of spalling. Moreover, utilizing both supplementary cementitious materials with recycled concrete aggregate can improve the fire resistance of concrete. The incorporation of pulverized fly ash and slag in Portland cement or blended cement can generally keep the mechanical properties of concrete at a higher level after heating to a high temperature.

Self-healing concrete is a revolutionary building material that will generally reduce the maintenance cost of concrete constructions. Self-healing of cracks in concrete structure would contribute to a longer service life of the concrete and would make the material more durable and more sustainable. The cementitious mortar with/without incorporating encapsulates at different percentages of slag replacement with the cement mix improves autogenous healing at different ages. Therefore, this study’s aim is to develop a self-healing cementitious matrix for repair and retrofitting of concrete structures.

In the present work, waste straw pipes are used as a capsule, filled with the solution of sodium hydroxide (NaOH), sodium silicate (Na₂SiO₃) and colloidal nano-silica as self-healing activators. An artificial micro-crack on the control and blended mortar specimens at different percentages of slag replacement with cement (with/without encapsulation) is developed by applying a compressive load of 50% of its ultimate load-carrying capacity. The mechanical strength and ultrasonic pulse velocity, water absorption and chloride ion penetration test are conducted on the concrete specimen before and after the healing period. Finally, the self-healing activity of mortar mixes with/without encapsulation is analysed at different ages.

The encapsulated mortar mix with 10% of slag content has better self-healing potential than all other mixes considering mechanical strength and durability. The enhancement of the self-healing potential of such mortar mix is mainly due to hydration of anhydrous slag on the crack surface and transformation of amorphous slag to the crystalline phase in presence of encapsulated fluid.

The self-healing activities of the slag-based cementitious composite are studied for a healing period of 90 days only. The strength and durability performance of the cracked specimen may be increased after a long healing period.

The outcome of the work will help repair the cracks in the concrete structure and enhances the service life.

This study identifies the addition encapsulates with a self-healing activator fluid that can recover its strength after minor damage.

The purpose of this paper is to focus on compressive strength modelling of cementitious mixtures like mortar and Roller-compacted concrete (RCC) containing rubber aggregates from shredded worn tires and filler using adaptive neuro fuzzy inference systems (ANFIS).

The volume substitution contains a ratio of rubber aggregates vs sand in mortar and with crushed sand in RCC and ranges from 0 to 50 per cent. As for the filler, they are substituted with sand by 5 per cent in mortar mixture. The methodology consists of optimizing the percentage of substitution in cementitious mixtures to ensure better mechanical properties of materials like compressive strength. The prediction of compressive strength and the optimization of cementitious mixtures encourage their uses in such construction pavements, in area games or in other special constructions. These cementitious materials are considered as friendly to the environment by focussing on their improved deformability.

The results of this paper show that the performance of the constructed fuzzy method was measured by correlation of experimental and model results of mortar and RCC mixtures containing both rubber aggregates and filler. The comparison between elaborated models through the error and the accuracy calculations confirms the reliability of the ANFIS method.

The purpose of this paper is to assess the performance of the constructed fuzzy model by the ANFIS method for two types of cementitious materials like mortar and RCC containing rubber aggregates and filler. The fuzzy method could predict the compressive strength based on the limited measurement values in the mechanical experiment. Furthermore, the comparison between the elaborated models confirms the reliability of the ANFIS method through the error and the accuracy calculations for the best cementitious material mixtures.

Important differentiating attributes in the procedures used, the characteristic mineral composition of the binders, and the implications these have on the final long term stability and physico-mechanical performance of the concretes produced are identified and discussed, with the intent to improve transparency and clarity in the field of geopolymer concrete technologies.

This state-of-the-art review covers the area of geopolymer concrete, a class of sustainable construction materials that use a variety of alternative powders in lieu of cement for composing concrete, most being a combination of industrial by-products and natural resources rich in specific required minerals. It explores extensively the available essential materials for geopolymer concrete and provides a deeper understanding of its underlying chemical mechanisms.

This is a state-of-the-art review introducing the essential characteristics of alternative powders used in geopolymer binders and the effectiveness these have on material performance.

With the increase of need for alternative cementitious materials, identifying and understanding the critical material components and the effect they may have on the performance of the resulting mixes in fresh as well as hardened state become a critical requirement to for short- and long-term quality control (e.g. flash setting, efflorescence, etc.).

The topic explored is significant in the field of sustainable concrete technologies where there are several parallel but distinct material technologies being developed, such as geopolymer concrete and alkali-activated concrete. Behavioral aspects and results are not directly transferable between the two fields of cementitious materials development, and these differences are explored and detailed in the present study.

This study aims to predict the fracture properties of geopolymer concrete, which is necessary for studying failure behaviour of concrete.

Geopolymers are new alternative binders for cement in which polymerization gives strength to concrete rather than through hydration. Geopolymer concrete was developed from industrial byproducts such as GGBS and dolomite. Present study estimates the fracture energy of GGBS geopolymer concrete using three point bending test (RILEM TC50-FMC) with different percentages of dolomite and compare with cement concrete having same strength.

The fracture properties such as peak load, critical stress intensity factor, fracture energy and characteristic length are found to be higher for GGBS-dolomite geopolymer concrete, when their proportion becomes 70:30.

To the best of the authors’ knowledge, this is an original experimental work.