Biomimetic Facade Applications for a More Sustainable Future

Mankind has often taken inspiration from the nature to solve problems since nature has sophisticated processes, refined for thousands of years. While manmade systems are unsustainable, natural processes embody sustainability principles; therefore, there are many things to learn from nature in order to solve design problems and create a more sustainable future. This is the promise of a biomimetic design approach. Another design approach is biodesign, and it also involves utilizing natural elements inside the design. The building façade is a problematic research area since it is at the intersection between living spaces and natural environment; thus it faces many problems especially regarding energy-air-water transition between indoors and outdoors. Application of key sustainability concepts in architecture such as energy requirements, form and structure, and sustainability considerations can be enhanced by learning from natural processes. This chapter looks at cutting-edge design principles, materials, and designs in building façades through the lens of biomimetics and biodesign. First, the design principles and then the materials and some cases are explained. The concepts of biomimicry and biodesign are in harmony with the concept of sustainability; however, to reach sustainable façade solutions, the sustainability principles should be at the core of the design problem definition

BETON AGREGALARINDA ALKALİ REAKTİVİTE YATKINLIĞININ TESPİTİ İÇİN RILEM YAKLAŞIMI

This paper mentions the alkali reactivity determination and reactivity degree classification for concrete aggregates in view of the work conducted by RILEM 219-ACS Technical Committee of which the author is a member between the years 2007-2014. Thus, it is aimed to introduce national researchers the latest developments on the way to internationally accepted test and aggregate evaluation methods in order to raise their awareness and disseminate the results of the committee work. In light of the technical committee reports from the past to present, state of the art recommendations and test methodologies are described, their comparative evaluation as well as possible further research topics on this area are presentedBu çalışma, yazarın 2007-2014 yılları arasında üyesi bulunduğu RILEM 219-ACS Teknik Komitesi çalışmalarının çıktıları ışığında beton agregaları için betonda zararlı genleşmeler ve çatlamalara sebebiyet veren alkali reaktivitesi tespiti ve sınıflandırılmasını anlatmaktadır. Bu sayede, uluslararası kabul görmüş standartların ve agrega değerlendirme metodolojilerine giden yolda ülkemiz araştırmacılarına son gelişmeler aktarılarak RILEM yaklaşımının tanıtımı ve yaygınlaştırılması amaçlanmaktadır. Geçmişten günümüze alkali agrega reaktivitesi konusunda çalışmalar yapmış olan teknik komitelerin bilgileri ışığında, güncel öneri ve test metotları tanıtılmış, karşılaştırılmalı değerlendirmeleri gerçekleştirilerek geliştirilmeye açık konular vurgulanmıştı

Alkali-agrega reaktivitesinin tespitinde kullanılan deney metotlarının incelenmesi

Bu çalışmanın amacı, üç farklı deney metodunun (ASTM C1260, ASTM C1293 ve beton mikrobar testi), hem İzmir yöresindeki agregaların reaktivite potansiyelini belirlemedeki davranışını kıyaslamak hem de bu yöredeki mineral katkı kaynakları ile lityum tuzlarının ASR üzerindeki etkilerini belirlemede karşılaştırmalı olarak incelemektir. Tezin ilk bölümünde çalışmanın amacı ve kapsamı açıklanmış, ikinci bölümünde genel olarak alkali agrega reaksiyonu anlatılmıştır. Üçüncü bölümde alkali silis reaksiyonu, dördüncü bölümde mineral ve kimyasal katkıların alkali silis reaksiyonuna etkisi, beşinci bölümde ise reaksiyonun tespitinde kullanılan deney yöntemlerinden bahsedilmiştir. Çalışmanın altıncı bölümü, deneysel çalışmada kullanılan malzemenin karakterizasyonu ile ilgilidir. Yedinci bölümde uygulanan mekanik deneyler karşılaştırılmalı olarak ele alınmış ve tartışılmıştır. Sekizinci bölümde reaksiyon sonucu oluşan ürünlerin morfolojisi ve kompozisyonu, genleşme değerleri dikkate alınarak incelenmiştir. Çalışma kapsamında toplam 60 adet harç, 66 adet beton mikrobar, 53 adet beton prizma karışımı hazırlanmış ve her bir karışımdan en az üç adet örnek dökülmüştür. Çalışmanın sonucunda, hızlandırılmış iki deney metodunun birbiriyle doğrusal ilişki verdiği ve bu yöntemlerin katkıların etkinliğini belirlemede konservatif olduğu belirlenmiştir. ASR ürünleri kompozisyonu ile genleşmeler arasında bağıntı bulunduğu anlaşılmıştır

A new method for determination of dynamic stability of self-consolidating concrete: 3-Compartment sieve test

There are many standard test methods and applications to determine or estimate the workability of fresh concrete mixtures, most of them are focused on highly flowable concrete mixtures. Due to its high flowability, self-consolidating concrete (SCC) is much more vulnerable to segregation compared to conventional concrete mixtures. Thus, researchers have been working on adopting dynamic and static test methods for determination and improvement of segregation stability of those mixtures. In this study, the different segregation test methods presented in the literature were assessed and a novel method, i.e. 3-compartment sieve test, was introduced. The dynamic stability of fresh self-consolidating concrete mixtures was evaluated by the suggested test method after slump-flow and J-Ring tests. In conclusion, the developed new method is recommended for determination of segregation in SCC due to satisfactory concurrency of results with those of visual stability index test (0.67 ? R2 ? 0.90) and sieve segregation resistance test (0.83 ? R2 ? 0.90), respectively. © 2018 Elsevier Lt

Bleeding characteristics of high consistency heavyweight concrete mixtures

Bleeding, a type of static segregation derives from density difference of concrete ingredients in fresh state. Due to having this difference higher than normal weight counterparts, heavyweight concrete is more susceptible to bleeding, thus, this type of concrete is commonly produced in low slump values. In order to give a response to advances and demands in concrete technology, heavyweight concrete mixtures with high slump values were designed at various mixture characteristics, and their bleeding characteristics were researched in the study. For this purpose, totally, thirty-five concrete mixtures with ?150 mm slump values were produced by using common cement replacement materials (silica fume and fly ash), viscosity modifier, and various water/binder ratios at two binder dosages. The mixtures showed excessive bleeding capacities ranged from 0 to 11.7% and bleeding rates ranged from 0 to 5.1 kg/m2/h. Silica fume was found as the most effective admixture for reducing or elimination of the bleeding. Bleeding time generally shorten at high binder content and at high water/binder ratio. It was observed that the bleeding adversely affects the hardened characteristics of heavyweight concrete mixtures. © 2018 Elsevier Lt

Beton Yapı Bileşenlerinin Isıl Yalıtım Özellikleri Yönünden İncelenmesi: Bir Derleme

1973’te yaşanan Petrol Krizi ile beraber doğal kaynakların kısıtlı olduğu anlaşılmış ve olabildiğince verimli kullanılması gerektiği gündeme gelmiştir. 1980’lerden itibaren ise küresel ısınmanın literatüre girmesiyle beraber “Enerji Etkinlik” günümüzde en gözde olan konulardan bir tanesi haline gelmiştir. Enerji harcamalarında binaların %32’lik gibi büyük bir paya sahip olması ise bina kabuğunun enerji etkin bir şekilde tasarlanması ihtiyacını doğurmaktadır. Bu açıdan ele alındığında en çok tüketilen yapı malzemesi olan betonun ısıl geçirgenlik değerinin düzenlenmesinin binaların enerji etkin tasarımında anahtar rol oynadığı son derece açıktır. Bu nedenle, çalışma beton yapı bileşenlerinin ısıl yalıtım yönünden incelenmesini konu edinmiştir.As one of the most important results of Oil Crisis in 1973 it has been understood that the natural sources are exhaustible and they ought to be consumed efficiently as much as possible. With discussion about Global Warming within the scope of scientific literature since 1980s “Energy Efficiency” became one of the most popular research topics until today. Since the buildings are responsible for 32% of total energy consumption energy efficient design of the building envelopes became more than an issue. As concrete is the most widely used construction material determining its thermal conductivity value by means of different techniques and experimental studies plays key role in energy efficient designing of buildings. Therefore, this study concerns with the evaluation of concrete building elements from thermal insulation viewpoint

Gamma-ray attenuation coefficients and transmission thickness of high consistency heavyweight concrete containing mineral admixture

In the study, high consistency heavyweight concrete mixtures containing barite aggregate were produced by using some common mineral admixtures (viscosity modifier, silica fume and fly ash) at various water/binder ratios and binder contents. Gamma-ray linear attenuation coefficients of the concrete mixtures were determined by using gamma sources of 137Cs and 60Co in NaI(Tl) gamma spectrometry system. The relationship between specimen thickness and transmission of the rays was constituted by emphasizing their mean free path, half-value layer, and tenth-value layer. Moreover, experimental mass attenuation coefficients of the concrete specimens were determined and compared with theoretical mass attenuation coefficients calculated by XCOM software depending on elemental fractions of these concrete in equivalent energies (662 keV, 1173 keV and 1332 keV). As a result, the replacement of the aforementioned admixtures with ordinary cement negatively affected the linear attenuation coefficients of the heavyweight concrete. A relative change of up to 25% was observed between the least and the highest attenuation thickness values at a certain gamma-ray transmission. A good regression relationship has been established between density and linear attenuation coefficients, density and mean free path, and density and half- or tenth-value layers of the heavyweight concrete. Theoretical (XCOM) mass attenuation coefficients were found similar to the experimental mass attenuation coefficients of the heavyweight concretes. Although there is a good linear regression relation between the theoretical and experimental mass attenuation coefficients at 662 keV energy of gamma rays, the relations were disappeared at 1173 and 1332 keV energies of gamma rays. © 2018 Elsevier Lt