Current Materials Science - Volume 13, Issue 1, 2020

Background: Nature has always played a vital role in the evolution of life forms. The design of products in accordance with nature’s design, popularly known as biomimicry, had played a vital role in pushing the technology and product effectiveness to the next level. Humans have long sought to mimic not just the design, but also the methodology adopted by certain animals. For example, the walking technique of vertebrates has been effectively mimicked for a quadruped robot to make a system more efficient by consuming less power. Thus indirectly, nature acts as a driving factor in pushing technological growth. Methods: The principle objective of this paper is to provide an overview of popular bio mimicked products inspired by nature. This paper emphasizes a wide variety of products developed in the field of materials inspired by nature. Results: Wall-climbing robots, Sonar, X-ray imaging, Sandwich and Honeycomb structures are some of the popular products and designs inspired by nature. They have resulted in better designs, better products with improved efficiency and thus have proven to be better alternatives. Some products and designs such as Samara drone, Riblet surfaces, DSSCs, Biomimetic Drills and Water turbines have plenty of scopes to replace conventional products and designs. Conclusion: While plenty of products, structures and designs have successfully replaced older alternatives, there is still a large scope for biomimicry where it could potentially replace conventional products and designs to offer better efficiency.

Background: The deposits of iron tailing will pose a great risk of environmental pollution and serious landscape impact which will affect the quality of life of humans. Therefore, it is urgent to utilize iron tailing to produce valuable products. Methods: The tailing ceramsites were analysed by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The roles of the tailing content, sintering temperature and duration time in the performance of the tailing ceramsites were analysed and the optimal sintering parameters were determined. Results: The bulk density, apparent density and cylinder compressive strength of the tailing ceramsites increase considerably with the increase of the sintering temperature and duration time. The cylinder compressive strength of the tailing ceramsites increases with increasing the tailing content. The optimal sintering parameter is 1100°C for 40 min. The cylinder compressive strength of the tailing ceramsites obtained at 1100°C for 40 min reaches 10.1 MPa. XRD analysis shows that the tailing ceramsites mainly consist of CaSiO3, Al2SiO5, MgSiO3, Ca7Si2P2O16, CaAl2Si2O8, Ca2Fe2O5 and SiO2 phases when the sintering temperature and duration time were increased to 1100°C and 40 min, respectively. Conclusion: The tailing ceramsites were obtained from iron tailing, sludge and fly ash as the raw materials at 1100°C for 40 min. The obtained ceramsites exhibited high mechanical performance.

Background: Results of an experimental study are given involving high-impact ballistic tests using .22 inch diameter ammunition (commonly known only as .22 ammunition) with the target set up as a combination of different numbers and weights of Kevlar layers. These experimental tests are conducted as literature indicating that the .22 projectiles are not as effective as with larger calibre ammunition. Present work is part of a research study to assess the safety limits of Kevlar layers of different weights against various calibre projectiles. Objective: The objective is to obtain test data to determine the number of Kevlar layers and weights needed for the design of safe bullet proof vests capable of stopping various size ammunition. In the present study, results are given for .22 inch ammunition, which provide data on the characteristics of high-speed ballistic penetration of .22 bullets into Kevlar layers and stopping distances in gel/Kevlar combinations. Methods: Tests were performed with Kevlar fabrics of different weights of Gram per Square Meter (GSM) to provide a comparison among different Kevlar fabrics as well as with different number of Kevlar layers. The tests were conducted with the use of a chronograph in a controlled test environment. The penetration depth in ballistic gelatine was recorded. Results: The results identify the number of layers of Kevlar required to stop a .22 projectile and the relationship between the different layers and weights of Kevlar materials. The results of the .22 projectile penetration are compared with those of different 9 mm Parabellum projectiles to assess the effect of different size ammunition on the bullet-proof capabilities of Kevlar. Experimental data on the penetration depths of different types of bullets into the gel/Kevlar combinations are presented using various graphs. Conclusion: The .22 projectiles perform similar penetration depths compared to that of 9 mm projectiles, and therefore cannot be considered as ineffective ammunition as literature has indicated.

Aims: Study the performance of self-compacting mortar (SCM) using waste ground brick as cement replacement material. Background: Large amounts of brick waste are produced in brick manufacturing plants and construction and demolition sites. The use of these bricks as partial substitution to natural aggregates or after crushing as fines for partial cement substitution could contribute to reduce the problem of waste storage and environmental pollution as well as in the conservation of natural resources. Objective: The objective of this paper is to study the effect of adding waste ground brick on the performance of SCM at the fresh and hardened state. Methods: It is an experimental investigation where mortar specimens where cement was partially substituted by crushed recycled bricks fines recovered from a brick plant. The level of substitution was either 0%, 5%, 10%, 15% 20% and 25% by weight of cement. Workability was measured by slump flow and flow time by V-funnel test. Compressive strength and water absorption by capillary were measured on 40x40x160 mm3 prismatic specimens. Results: The experimental results show that self-compacting mortar can be obtained up to 25% of cement substitution by brick powders. The compressive strength was improved at long term for up to 15% cement substitution by brick powder. The sorptivity coefficient is increased by incorporation of brick waste powder. Conclusion: The substitution of cement by waste ground brick powder up to 15% of waste brick powder has little influence on the rheological parameters of self-compacting mortar and the compressive strength is increased at the long term. Further investigations are underway to study the shrinkage, the long term durability and the pore size distribution by mercury porosimetry.

Aims: To produce a low environment impact concrete by recycling waste brick and waste marble. Background: Marble and brick wastes are produced as a byproduct during manufacturing or cutting processes. These materials could be used as a substitution to cement in mortar and concrete to reduce its environmental impact. Objective: To study the performance of self-compacting mortar with marbles and brick powders at the fresh and hardened states. Methods: It is an experimental investigation where two Blaine finenesses of marble and brick powders were used. Rheological, mechanical and physical properties of the new composites were studied. Results: The results show that for optimal workability and compressive strength of SCM, the maximum percent of substitution must not exceed 5% for brick powder, whereas for marble powder it can reach up to 20% according to the fineness of powder. The incorporation of brick and marble powders separately decreases the shrinkage of SCM and the combination of both powders has a positive effect on its sorptivity coefficient and total shrinkage. Conclusion: Maximum 5% and 20% of brick and marble powder respectively are recommended for optimal properties of self-compacting mortar.

Aims: The aim of this study is to discuss the performance of SCC with natural pozzolana under hot climate conditions. Background: The performance of vibrated concrete under hot climate is well investigated. However, the effect of hot climate on SCC is tittle investigated. North African and Middle Eastern countries are subjected to hot and dry environments especially during summer periods. Hence there is a need to investigate the performance of SCC under hot climate. Objective: The objective of this paper is to study the effect of water curing duration followed by natural hot climate exposure on the performance of SCC with Natural Pozzolan (NP). Methods: It is an experimental investigation where Concrete specimens were exposed to a standard curing environment (relative humidity RH = 100% and Temperature T°= 20°C ± 2°C) for 0, 1, 3, 7, 14 and 28 days, followed by a second cure in a hot environment in open air on a laboratory terrace in North Africa area during summer time with a temperature of 35°C to 45°C and a relative humidity of 65% to 75%. The cement was substituted by NP in weigh at three substitution levels (0%, 15% and 25%). Results: The experimental results show the importance of the wet curing in hot climate, especially when NP is used. Substituting cement by NP improves the self-compacting concrete durability for the long term. Conclusion: The substitution of cement by natural pozzolan reduced water permeability and capillary absorption. The hot climate has no negative effect on the evolution of the mechanical strength and durability of the SCC with natural pozzolan when undergoing a long initial wet cure.