Frontiers in Biomaterials

Natural organisms consist of an integral, multi-layered, finely tuned and differentiated combination of basic components and may act as role models in providing kinematic principles to structures subjected to time-varying external conditions. The term biomimetic design is introduced in the present chapter to refer to the synthetic integration of nature mechanisms considered in the development and composition of kinetic structures. Respective kinematic principles transferred in the design of structures follow performance-based open-loop design processes, made possible through interdisciplinary modes of operation in research and design. Following initial visions of kinetic architecture in achieving structural flexibility and adaptability, respective prototype developments, achieved until recently, follow a hardmechanical approach that enables the development of deployable and transformable actuated bar structures. Confronted with implicated geometrical limitations, the mechanical complexity and high energy consumption of such systems, a design approach derived from soft mechanics is hereby proposed. So far, few realizations of bending-active elements and hybrid systems with enhanced reversible elastic deformability are based on plant movement principles. Following an overview of related form-finding simulation and analysis methods, further bio-pulse oscillation processes, present in nature, are proposed to extend the biomimetic design spectrum. In a case example, motion principles of jellyfish pulse oscillations have been transferred, scaled-up, and integrated into the design of a high-rise structure.

Trusses are designed for supporting loads while ensuring reduction in material consumption and providing stability. Following these principles, nine types of structural trusses were designed using the Stiffness Method. Details of the trusses include: 20 m span, 1 m height, concentrated load of 10 kN (at the centre of the structure), with profiles composed of circular steel bars (ASTM A36, 210 GPa for modulus of elasticity). The trusses differed from each other specifically in the height (truss)/length (chord) ratio. The ratio values varied between 44.44 cm and 100.00 cm. The profiles were sized for carrying solely loads anticipated in the structural design, with no unloaded cross sections. The results included material consumption for each structural type: TRUSS 1 (110.39 kg), TRUSS 2 (106.26 kg), TRUSS 3 (105.04 kg), TRUSS 4 (104.25 kg), TRUSS 5 (103.83 kg), TRUSS 6 (105.63 kg), TRUSS 7 (105.91 kg), TRUSS 8 (108.47 kg), and TRUSS 9 (113.38 kg). The results indicated that the truss with the lowest material consumption also used a height/length ratio corresponding to the Golden Ratio, a value frequently encountered in nature. This Golden Ratio provided a minimal consumption of material, while maintaining structural stability. As for strain, nothing was identified (unfortunately!). Nowadays, it is not surprising when this value is identified in nature, but when the Golden Ratio is indirectly encountered in an essential technical human activity, it is relevant; not for human advantage, on the contrary, nature seems to be communicating something to humanity in its own language. Would this language be what is currently called biomimetics?

This chapter deals with the issues related to the complexity and adaptability of human to nature. What is complexity in a complex world? Seven concepts/properties of complexity are presented. The world created by humans demands of itself changes of posture relative to its adaptation, without this, the planet Earth does not seem to be a friendly environment to live. Thus the science of complexity is necessary to make everyday relations, once marked by simplicity, occur without trauma, since they are necessarily complex. What does it take to adapt to the world of complexity? Coping with disruptions, defending from attacks, resolving conflicts, correcting drift into failure, and avoiding stagnation. Necessary tools for adapting the technology for designing complexity into organizations, processes and products references are presented: architecture, multi-agent software works, organizational, and process design cases, engineering design cases, etc. It is not known how the future will be, but certainly complexity will be one of its characteristics.

The present study aims to present a new concept and, possibly, a new trend in the context of architecture, called Concrete Nullification in Architecture and is based on the philosophical reflections of the French philosopher Jean Paul Sartre. On the basis of certain bio-inspiration and bio-design assumptions, it presents an actual building, located in the city of Brasília - DF, Brazil, comprising the concepts of Emptiness and Nullification. Its layout and interior dimensioning were designed with an absence of walls or internal physical divisions. This new housing concept is called OW (Ohne Innerwände) aiming through the construction process at a better disposition and reflection of contemporary living, which maximizes space utilization, improve light capture, ventilation, ergonomics, accessibility and acoustics. In this proposal, the interdisciplinary nature of knowledge is used to form a root-like network of architecture, anthropology, and philosophy which enables flow in the description and implementation of the proposed house, beginning with an explanation of the philosophical concept of nullification as developed by Sartre.

This chapter deals with the issues related to packing of particles in nature – aggregate in the first place - and in cementitious materials. Many of these topics are extensively discussed in the international literature, so will only be briefly introduced, while additionally giving a restricted number of references. Relatively new developments, such as producing the realcrete by computer, yielding compucrete, will receive more explicit attention. The way to do this properly by DEM (discrete element method) instead of by popular RSA (random sequential addition) is stressed. Modern dynamic DEM renders possible simulating aggregate of fluvial origin as well as of crushed rock. Similarity of simulating particle packing on mesolevel (aggregate) and on microlevel (binder) was the argument to sketch modern developments in the latter field, because they provide information on permeability and are thus of paramount important for sustainability. A phenomenon recently receiving attention in the literature is Brazil Nut Effect. It is a part of nature and it can significantly influence the compacted particle structure of aggregate or binder alike. Some relevant information as to cementitious materials will be provided.

A more sustainable and conscientious world desires to go back in time to use environmentally friendly construction materials, earthen materials. However, the simplicity of such materials has not yet been properly addressed in either academic or field research; at the same time natural earth construction is far from mature. In this scenario, we summarize the development of natural earth construction during the last few years. Recent publications including a number of books and journals on natural building are reviewed, while emphasizing the impacts of field research. Controversies and gaps in understanding are identified, and we discuss the advances of these modern ideas through the years. Topics include a review of natural earth building; materials selection; property evaluation; academic and field studies; and a state-of-the-art review on current developments (Adobe, Compressed earth blocks, Cob, Rammed earth, Earthbag construction, Earth floors, and Earth wall finishes). Recent developments in standards for earthen building materials are also reviewed. This chapter concludes with perspectives and future needs in natural earth construction, those which may have significant impacts on the advancing field.

This chapter intends to present general information about bamboo; the fast growing grass with excellent mechanical properties. The potential of this material for Architecture and Construction is discussed. Information concerning how to obtain the plant and select appropriate culms/stems, to be employed for building is explored. Physical properties as revealed through research in Brazil are also presented. As for bamboo’s mechanical properties; compressive, tensile, and shear strength parallel to the fibers are presented along with numerical values for various species. Specific applications for bamboo, such as concrete reinforcement are also presented. And finally, the potential of bamboo vessel impregnation with polymeric resins is described.

Biominerals are structures essential to their host organism, for which they provide varying functions and features. Through evolutionary optimization, they present sublime material properties as yet unparalleled in anthropogenically created materials. Formed at ambient temperatures from benign materials, the underlying formation processes and mechanisms still challenge our understanding. In this essay, we identify three key challenges which must be overcome to successfully emulate advanced biomimesis of ceramic materials. As frontiers singled out from the various challenges involved in mimicking biomineralization in vitro, three fundamental lines of research are represented: (i) temporal control of mineralization, (ii) spatial control of mineralization by self-organizing scaffolds and, finally, (iii) control of mineralization by nonclassical crystallization and thus unconventional mechanisms which are not yet part of the pertinent physicochemical canon. We expect that by mastering these aspects, the discipline of bio-inspired mineralization will take us far beyond where we are today.

Biocement is a mixture of at least three components: (i) a principal inorganic component producing binding matter, (ii) a component that changes pH and initiates precipitation of binder; and (iii) an enzyme, live microbial cells, or dead but enzymatically active microbial biomass that catalyzes pH changes and/or other biochemical reactions. The inorganic component is usually a dissolved calcium, magnesium, or iron salt which is transformed into a non-dissolved compound. A component that changes pH and supplies CO2 for carbonation is usually urea, nitrate, formate or acetate, that are hydrolyzed, oxidized or reduced under catalytic action of microbial cells or enzyme. Biogrouts are similar to biocements, but used in lower dosages than biocements. Their application objective is to diminish hydraulic conductivity of soil, fractured rocks, or concrete cracks. A principal advantage of biocements and biogrouts over conventional cements and grouts is the low viscosity of their solutions/suspensions; such that biocements and biogrouts can be used for deep penetration into porous soil, fractured rocks, or concrete cracks. There are about 15 different types of biocement/biogrout. The most popular class of biocement and biogrout is abbreviated as MICP (Microbial Induced Calcite Precipitation), and based on the formation and adhesion of calcium carbonate crystals produced from a concentrated solution of calcium ions and urea. The process is used to fill pores and bind particles with calcium carbonate crystals. This is initiated by urea hydrolysis by urease-producing microorganisms but it is not environmentally-friendly process. Specific killing of bacterial cells that leave their urease activity intact increases the biosafety of biocementation/bioclogging processes. Biogrout with killed bacterial cells has been demonstrated to decrease hydraulic conductivity of sand from 5×10-4 m/s to 3×10-8 m/s. To decrease the expense of biocement/biogrout, a bioagent can be produced from hydrolyzed activated sludge. In practice, biocements and biogrouts can be used for strengthening and sealing slopes, agricultural channels, the construction sites, the aquaculture and wastewater treatment ponds, the landfill and soil-polluted sites, the dams and retaining walls, the tunneling space before or after excavation, for the road construction, dust and erosion control, for decontamination of CBRN agents on polluted land and infrastructure, for the coating of the artificial coral reefs or concrete coastal constructions, and many other environmental, agricultural and civil engineering applications.

Lignocellulosic fibers are obtained from agriculture (60%) and forests (40%) industry. Tropical countries produce high amount of these fibers as a by-product. The use of natural fibers is interesting due to their biodegradation capabilities as well as their damping properties, low density and moderate strength. Hence, in the present chapter, the facts due to which natural fibers can be used as reinforced polymers along with the importance and role of the interfacial region will be discussed. In addition, the effect of incorporating chopped natural fibers of different length, as disperse reinforced phase, on the dynamic or quasi-static elastic modulus of glass fiber laminates will be analyzed. A glass fiber composite material model used as a coir fiber effect test bed and a simple, easy and sensitive cantilever experimental setup were validated which are presented with comparative results.