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This paper aims to report on the experiments with the Contour Crafting Automated Construction process using sulfur concrete as the choice of construction material.

Several experiments have been performed at centimeter and meter scales. A finite element analysis simulation model for the behavior of sulfur concrete-based structures has been developed. Experimental results were compared with the results of simulation.

Sulfur concrete has numerous terrestrial applications and is potentially an ideal construction material for planetary construction.

Experimental samples of sulfur concrete were fabricated using a novel mixer/extrusion system. The mechanism was proven to be durable and stable after more than 500 h of work.

Specific chemical environments step out in the industry objects. Portland cement composites (concrete and mortar) were impregnated by using the special polymerized sulfur and technical soot as a filler (polymer sulfur composite). Sulfur and technical soot were applied as the industrial waste. Portland cement composites were made of the same aggregate, cement and water. The durability of prepared cement composite samples was tested in 5 per cent solution of HCl and 5 per cent solution of H₂SO₄ as a function of immersion time. The changes in mechanical strength and mass of the samples were periodically measured. Cement composites impregnated with sulfur composite exhibited limited mechanical strength and mass loss, whereas physico-mechanical properties of Portland cement concrete regressed rapidly. The loss in weight of ordinary concrete impregnated with sulfur composite, kept in aqueous solutions of acids, hydroxides, salts and in water for a year was determined using 100 × 100 × 100 mm samples. The same samples were then used in compressive strength tests.

Specific chemical environments affect industrial objects. Portland cement composites (concrete and mortar) were impregnated with a special polymerized sulfur and technical soot as a filler (polymer sulfur composite). Sulfur and technical soot were applied as industrial waste. Portland cement composites were made of the same aggregate, cement and water. The durability of the prepared cement composite samples was tested in 5 per cent solution of HCl and 5 per cent solution of H₂SO₄ as a function of immersion time. The changes in mechanical strength and mass of the samples were periodically measured. Cement composites impregnated with sulfur composite exhibited limited mechanical strength and mass loss, whereas the physico-mechanical properties of the Portland cement concrete regressed rapidly. The loss in weight of ordinary concrete impregnated with sulfur composite, kept in aqueous solutions of acids, hydroxides, salts and in water for a year was determined using 100 × 100 × 100 mm samples. The same samples were then used in compressive strength tests. The image analysis used for surface destruction monitoring, performed by scanning microscopy for the determination of damaged surface area and the original surface area before acid resistance testing, showed similar results. Based on the image analysis results, a model for predicting the degradation of mechanical strength during durability testing was established. The fact that the calculated and experimental strength values were not vastly different proved the validity of the proposed model. A brief summary of new products related to the special sulfur composite is given as follows: impregnation, repair, overlays and precast polymer concrete will be presented. Sulfur composite as a polymer coating impregnation, which has received little attention in recent years, currently has some very interesting applications.

Author comments: The article is original. The article has been written by the stated authors who are all aware of its content and approve its submission. 3. The article has not been published previously. 4. The article is not under consideration for publication elsewhere. 5. No conflict of interest exists, or if such conflict exists, the exact nature must be declared. 6. If accepted, the article will not be published elsewhere in the same form, in any language, without the written consent of the publisher.

Author comments: 1. The article is original. 2. The article has been written by the stated authors who are all aware of its content and approve its submission. 3. The article has not been published previously. 4. The article is not under consideration for publication elsewhere. 5. No conflict of interest exists, or if such conflict exists, the exact nature must be declared. 6. If accepted, the article will not be published elsewhere in the same form, in any language, without the written consent of the publisher.

In recent years, 3D printing technologies have been widely used in the construction industry. 3D printing in construction is very attractive because of its capability of process automation and the possibility of saving labor, waste materials, construction time and hazardous procedures for humans. Significant researches were conducted to identify the performance of the materials, while some researches focused on the development of novel techniques and methods, such as building information modeling. This paper aims to provide a detailed overview of the state-of-the-art of currently used 3D printing technologies in the construction areas and global acceptance in its applications.

The working principle of additive manufacturing in construction engineering (CE) is presented in terms of structural design, materials used and theoretical background of the leading technologies that are used to construct buildings and structures as well as their distinctive features.

The trends of 3D printing processes in CE are very promising, as well as the development of novel materials, will gain further momentum. The findings also indicate that the digital twin (DT) in construction technology would bring the industry a step forward toward achieving the goal of Industry 5.0.

This review highlights the prospects of digital manufacturing and the DT in construction engineering. It also indicates the future research direction of 3D printing in various constriction sectors.

The first reports of sulphur composites were made nearly 140 years ago but it is only recently that sulphur based corrosion‐resistant concrete became available. The article describes the properties and advantages of the material.

This paper aims to investigate the extrudability (flow-ability and shape-stability) of concrete mixtures by using contour crafting (CC) as an automated construction process.

Several experiments have been performed for flow-ability and shape-stability of concrete mixtures. Experimental results were compared to understand significant factors and their interactions. After developing the empirical model for flow-ability, the model was validated.

The experimental investigation of varied combination of concrete components developed a mixture within constrains of the CC nozzle and improved the quality of the extruded part.

Several experimental samples were fabricated using CC, and the derived empirical model was validated after more than 700 h of work.

This paper aims to investigate the strength at interlayer of specimens fabricated using Contour Crafting (CC) to develop a concrete mixture for large-scale three-dimensional printing.

The collected data from several experiments were analyzed to understand significant factors and their interactions. After developing the empirical model, condition for maximum desirability was identified and the model was validated.

The experimental investigation of varied combination of concrete components introduced an empirical model which can predict the strength at interface. Moreover, an optimized mixture within constrains of the CC nozzle was developed and validated.

Several experimental samples were tested, and the derived empirical model was validated after more than 600 h of work.

The corrosion of reinforcing steel is considered the most critical problem for the durability of reinforced concrete structures. This study shows the experimental results of the corrosion of steel bars in mortar, using an accelerated test. The results indicate that increasing water/cement ratios accelerate the corrosion of reinforcing steel. In addition, increasing curing times decrease steel corrosion rates. The results also show that the cover to bar diameter ratio plays a significant role in determining the corrosion intensity. For the same cover thickness, the corrosion intensity increases as the steel bar diameter increases.

The purpose of this study was to reuse cement kiln dust (CKD) in cement products and report the results of determining the long-term compression and flexural tensile strengths of mortars containing CKD as a partial replacement of sulfate-resistant cement (SRC). During the manufacturing of Portland cement, voluminous quantities of the byproduct dust are produced, which is commonly known as CKD. In the past decade, according to environmental requirements, many researchers have attempted to reuse CKD in cement products.

The long-term compression and flexural tensile strengths of mortars containing CKD as a partial replacement of SRC were tested. The replacement ratios in this study were 0, 5, 10, 15 and 20 per cent. The specimens were exposed to a highly saline environment after normal curing in water for a 28-day period.

The results indicated a slight increase in the strength of CKD–SRC mortar containing 10 per cent CKD and moderate sulfate resistance when the CKD ratio reached 20 per cent, as compared to the reference mortar. In addition, CKD did not adversely affect the properties of SRC mortar subjected to sulfate exposure, even after one year.

The tests were inducted for the first time on SRC, and the new results can be used to produce an environmental-friendly concrete.

Besides with a large amount of Na⁺ and Cl⁻ ions in seawater, the presence of Mg⁺² and SO₄⁻² ions builds more complex corrosion mechanism. This paper aims to investigate the corrosion of embedded reinforcement in concrete with the environment of both Cl⁻ and SO₄⁻² anions associated Mg⁺² cation.

The concrete specimens were prepared by using ordinary Portland cement (OPC), and OPC blended with metakaolin (MK) for water to cementitious material ratio (w/cm) 0.48 and 0.51. The concrete mixes were contaminated with the addition of MgCl₂ alone and combined MgCl₂ and MgSO₄ in mix water. Reinforcement corrosion was evaluated by half-cell potential and corrosion current densities (I_corr) at regular intervals. Moreover, the influence of cementitious material type, salt type and w/cm ratio on electrical resistivity of concrete was also investigated. The statistical models were developed for electrical resistivity as a function of calcium to aluminium content ratio, compressive strength, w/cm ratio and age of concrete.

Although the corrosion initiation time increases in the concomitant presence of MgSO₄ and MgCl₂ as internal source compared to MgCl₂, I_corr values are higher in both OPC and MK blended concrete. However, electrical resistivity decreased with addition of MgSO₄. MK blended concrete performed better with increased resistivity, corrosion initiation time and decreased I_corr values.

This study reports statistical distributions for scattered I_corr of rebar in different concrete mixtures. Stepwise regression models were developed for resistivity by considering the interactions among different variables, which would help to estimate the resistivity through basic information.

Large P.T.F.E. agitator from LPP proved over 3 years Laminated Plastic Products of Ware were asked by Albright & Wilson some 3 years ago to supply a large corrosion resistant agitator for their chemical plant at Oldbury, Birmingham.