Concrete

Due to its prevalence in modern infrastructure, concrete is experiencing the most rapid increase in consumption among globally common structural materials; however, the production of concrete results in approximately 8.6% of all anthropogenic CO2 emissions. Many methods have been developed to reduce the greenhouse gas emissions associated with the production of concrete. These methods range from the replacement of inefficient manufacturing equipment to alternative binders and the use of breakthrough technologies; nevertheless, many of these methods have barriers to implementation. In this research, we examine the extent to which the increased use of several currently implemented methods can reduce the greenhouse gas emissions in concrete material production without requiring new technologies, changes in production, or novel material use. This research shows that, through increased use of common supplementary cementitious materials, appropriate selection of proportions for cement replacement, and increased concrete design age, 24% of greenhouse gas emissions from global concrete production or 650 million tonnes (Mt) CO2-eq can be eliminated annually.

With increased awareness of the emissions of greenhouse gases (GHGs) and the significant contribution from the cement industry, research efforts are being advanced to reduce the impacts associated with concrete production and consumption. A variety of methods have been proposed, one of the most common being the replacement of cement as a binder in concrete with supplementary cementitious materials, such as fly ash (FA), which can have lower environmental effects. The use of FA can change the kinetics of the hydration reactions and, consequently, modify the evolution of the concrete strength over time. Yet the influence of designing structural elements to obtain the required strength at later ages has not been examined in terms of their influence on global warming potential (GWP) of concrete. This research investigates the influence of design age, in addition to mix proportions and geometric aspects, on the GWP associated with making beams, columns, and a concrete building frame. Findings suggest that while the GWP for beams is not highly dependent on concrete mixture strength, the GWP for columns is dependent on strength, thus the influence of required strength at later ages influences GWP of making columns more so than beams. For the concrete frame analyzed, a potential 45% reduction in GWP, depending on mix proportions and design age, was found. Using the findings from this research, the GWP associated with production of concrete in California could be reduced by approximately 1.8 million metric tons of CO2-eq emissions, equivalent to approximately 2% of all industrial GHG emissions in California.

Laboratory tests were carried out to investigate the effect of steel fibres and recycled aggregate on the drying shrinkage and creep deformations of concrete. Steel fibres (Dramix 3D 65/35BG) were added to the mixes and washed construction and demolition wastes (CDW size 20mm) were used as a coarse recycled aggregate. The main variables of this study are the steel fibre contents; Vf = 0, 0.5 and 1.0% and the recycled aggregate replacement percentages; RP= 0, 50 and 100%. Small prisms (75×75×200mm) and bobbins (75×365mm) were cast (for 9 mixes), cured (for 28 days) and tested (for up to 90 days). A fine natural aggregate was used in all mixes and the amount of cement and the water-to-cement ratio was kept constant. The results showed that there are significant increments in drying shrinkage, compressive creep and tensile creep by 18%, 15% and 8% were recorded respectively when 50% of the recycled aggregate was used. However, when 100% of the recycled aggregate was replaced, the following results were achieved 38%, 29% and 15% respectively. In contrast, the effect of adding 0.5% of steel fibres content recorded reductions in these deformations (drying shrinkage, compressive creep and tensile creep) by 7%, 3% and 10% respectively. However, further reductions with percentages of 15%, 5% and 20% respectively were seen when 1.0% of fibre content was added. Interestingly, steel fibres had a significant effect on tensile creep and shrinkage, but little effect on compressive creep.

There is a growing interest in using waste materials such as ceramics as alternative aggregate materials for construction. While other ceramic product wastes such as sanitary wares and electrical insulators have been extensively investigated, not much findings are available on ceramic wall and floor tiles wastes. Thus, the current study focuses on the mechanical characterization of waste ceramic wall and floor tiles aggregate concrete. Ceramic wastes sourced from construction and demolition wastes were separated from other debris and crushed using a quarry metal hammer. Ceramic tiles were sieved into fine and coarse aggregates in line with standards. Other materials used were gravel, river sand, cement and potable water. Workability of the fresh concrete was checked through slump test, and concrete cubes of 150 mm dimensions and cylinders of 100 mm  200 mm were cast in the laboratory. After 24 h of casting, the concrete samples were demolded and were cured by immersion in water tank at temperature of 22 °C. The compressive and split-tensile strengths of the hardened concrete samples were determined after curing them for 3, 7, 14 and 28 days. Results showed that both the compressive strength and split tensile strength increased appreciably with the curing age than the conventional concrete.

The research presented in this paper utilizes industrial robotic arms and new material technologies to model and explore a prototypical workflow for on-site robotic collaboration based on feedback loops.This workflow will ultimately allow for the construction of customized, free-form, on-site concrete structures without the need for complex formwork.The paper starts with an explanation of the relevance of collaborative robotics through history in the industry and in architecture.An argument is put forward for the need to move towards the development of collaborative processes based on feedback loops amongst the designer, the robot and the material, where they all inform each other continuously.This kind of process, with different degrees of autonomy and agency for each actor, is necessary for on-site deployment of robots.A test scenario is described using an innovative material named concrete canvas that exhibits hybrid soft fabric and rigid thin-shell tectonics.This research project illustrates the benefits of integrating information-embedded materials, mass- customization and feedback loops. Geometry scanning, parametric perforation pattern control, computational analysis and simulation, and robotic fabrication were integrated within a digital fabrication deployment scenario.The paper concludes with a detailed report of research findings and an outline for future work.

Cement is used as a binder in concrete and is a must for strength and durability of concrete. Cement production is one of the many sources of air pollution which in turn is responsible for climate change. Colossal interest in partial substitute of cement has been observed in this decade to somewhat control the immense production and to bring other sources which are comparatively cheaper and environment friendly. Similar attempt has been made to investigate the effect of pulverized fire clay used as partial substitute of cement. The mechanical properties (compressive, flexure strength) and acid resistance has been analyzed where 10% fire clay replaced samples shown higher compressive strength as well as better acid resistance than controlled or plain concrete mixes. Microstructure analysis via SEM (Scanning electron microscopy) and XRD(X-Ray diffraction) help analyze the microstructure the way different products were formed and the compactness of the structure. Test results substantiate the feasibility to develop low cost concrete using Fire clay. It will reduce energy consumption and greenhouse gases produced during the manufacturing process of cement.

A plastic construction material, reinforced concrete, characterizes the last century and plays a leading role in the built environment. In the early 20th century Turkey, following the initial use of reinforced, reinforced concrete had been part of the modernization project in the setting up of a new Republic. Having been coincided with the spread of Modern Movement, reinforced concrete had been accepted as a material that symbolized as a fundamental break from the past. And until the mid twentieth century, there had been an intense endeavor to transfer its technology by the educators and the founders of the state. In post-war period, along with the decrease in the use of alternative building materials, reinforced concrete has become the dominant material in the building and housing industry.  The tremendous social, economic, social and political changes are, in general, identified with the decade of the 1950s, when the Democrat Party (DP) came into power replacing a 23-year-long-one-party governance. In this contextual framework, the decade of the 1950s present a multi-partite visual cultural formation providing to contact with the culture of reinforced concrete. Having been a milestone for the production of reinforced concrete, three important changes can be indicated in the decade of the 1950s: the first one is that the reflections of the governance changes (large scale investments concentrated on the urban infrastructure, cement industry and building sector in populist economic policies); the second one is that the discursive formations of ‘international style’ again dominated architectural culture in the transition oriented ‘internationalization’ in political discourses; and the third one the emergence of the reinforced concrete into the public daily life. In the new political climate of the 1950s, reinforced concrete had been ‘socially re-constructed’, institutionalized and culturally embedded in society-wide.

In this context, this study aims at investigating discursive formations in the threshold of the 1950s, lied behind the increase of the significance of reinforced concrete in the building sector. The paper compares considerable number of buildings which have a crucial role in the construction of an image in the collective memory through the representations in printed media as well as in the discourse of the social actors. The study, analyzing the publications in the media, the role of architectural writings, focuses  on the process of cultural re-composition of the reinforced concrete and its embedded meanings. First of all, tracing Certeau’s emphasis on different discursive formations in ‘strategy and tactic discussion’, the study offers a short theoretical framework. Secondly, it gives a contextual reading of the built environment as well new reinforced concrete buildings. Thirdly, it indicates
‘imaginations’ and ‘ideologies’ built in the context of the 1950s in Turkey, influencing building practices of reinforced concrete.

Studying imaginations/constructions of the reinforced concrete through the daily life may give a broader understanding of the modernity project in Turkey and in general.