This article presents the results of the application of a new form-finding tool for creating free-form compression-only shell structures. This tool is based on the force density method together with topological mapping. The great advantage of this design tool is that it unifies the creative process of design, form-finding, and analysis of the compression structure and allows creating well-conceived structures. The main advantage of the use of topological mapping is that no initial shape is needed but only the coordinates of the supports. The article presents the algorithm for generating compression structures using this powerful tool and a few resulting shells of different shape, span and material (steel-and-glass, concrete, Catalan vault) received using this algorithm.

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Durability of reinforced concrete structures including electric arc furnace slag as aggregate in chloride environment is a significant topic to enable their performance stable in their service period. In this study, chloride penetration in recycled concretes including gradation of fine and coarse aggregate that is electric arc furnace (EAF) slag is tested and compared with that of reference concrete including just natural aggregate gradation. To observe chloride penetration effect, concrete samples are exposed to a saline attack firstly; and then, total chloride content and chloride penetration profiles are tested. The Part I of the study argues the effect of aggregate of electric arc furnace slag on durability of reinforced concrete structures in chloride environment in the Introduction and Background section and the Materials and Methods section. Second part of the study is going to present the Results and Discussions section and the Conclusions section. Both part have the Abstract section and Reference section differently each other.

The global production of concrete represents, every year, more than 5% of the anthropogenic emissions of carbon dioxide, mainly from the production of cement. This negative factor can be improved by incorporating supplementary cementitious materials in order to replace cement. In the last few decades, research has been conducted on what it is known as Ultra High Performance Fibber Reinforced Concrete (UHPFRC). The term includes a broad range of materials such as defect-free, dense particle, engineered composite, multi-scale particle and fibber-reinforced cementitious materials, with enhanced properties. UHPFRC has better mechanical and durability properties compared to normal strength concrete. Other benefits of using UHPFRC on a structure includes the reduction of concrete sections, concrete formwork, labour, equipment and time of construction. Despite of the benefits associated to this material, the UHPFRC is still struggling to be universally applied, mainly due to its high cost and its high environmental impact. UHPFRC cost is higher than normal concrete, due to a very high powder content and steel fibber addition. However, the production of UHPFRC using locally available materials, under normal curing conditions, should reduce its cost and turned it into a more attractive construction product. In this paper, the fresh and hardened properties of a specific UHPFRC composition are presented. The mixture replaces a significant percentage of cement by slags, and the results reveal the viability of the proposed mix. The environmental performance of the mixture confirmed the improvement on the material sustainability and allowed the identification of some potential future studies.

Second part of the study presented argues the effect of aggregate of electric arc furnace slag on durability of reinforced concrete structures in chloride environment based on the Results and Discussions section and the Conclusions section. Both part have the Abstract section and Reference section differently each other. Results display that the EAF slag aggregate is favorable because of increasing the durability against chloride damage and of stoping the penetration of free chloride measured with method of the colorimetric test as well as wet chemical analysis. However, the study also answers that the wet chemical analysis is still the best method to measure the penetration of free chloride in concretes.