A Visionary Approach Study about the Member Construction Firms of Turkish Contractors Association (TCA)

In this study Turkish Contractors Association (TCA) members construction fims’ visionary approaches were investigated. A questionnaire has applicated to technical and administrative elements who works in 56 construction firms for evaluation of visionary approach of these firms. In this wise general profile of these firms’ evaluation of visionary approach has been understand and which firms emphasize which characteristics in determine vision investigated. Acquired by findings; these firms emphasizes their quality, trust and technologies in first three; their tangibility, being polyhedral and sensuality followed them. These fims’ emphasis to quality ratios were 64.3%, emphasis on job security were 32.1% and environmental stres ratio were 35.7% in their visions. Turkish construction firms have to create and applicate the most appropriate strategies for being successfull in global competitive race and to carry that success into long term. Our companies’ competitive advantage by providing with a strategic advantage are associeted with their visions

The Effect of the Rate of Waste Tire Powder Substitution on the Physical and Mechanical Properties of CEM II Cement

Recycling of waste has a great importance in preservation of the energy and decreasing the global impact that has been created by production of new materials. There is an increasing debate about the use of waste tires because of their environmental and health affects. Waste tires can be used for a range of civil engineering applications. This study investigates the physical and mechanical properties of CEM II (reference) and waste tire powder substituted cements. For this purpose, waste tire powder was substituted as a replacement for CEM II cement in amounts of 0, 2.5, 5, 7.5 and 10 weight %. The effects of waste tire powder on compressive and flexural strength, setting time, water demand and volume expansion were determined by standard tests of cement. As a result, a relative increase according to reference cement pastes was determined in the setting time of the waste tire powder substituted cement pastes. Besides these, a decrease were identified with the 2, 7, 28 and 56 days flexural and compressive strength tests for the waste tire powder substituted cement mortars according to reference cement mortars

TAHRİBATSIZ TEST SONUÇLARI KULLANILARAK UÇUCU KÜL İKAMELİ BETONLARDA BASINÇ DAYANIMININ ANFIS İLE TAHMİNİ

Bu araştırmada, tahribatsız test sonuçları kullanılarak uçucu kül ikameli betonlarda basınç dayanımının tahmini için uyarlamalı sinirsel bulanık mantık (ANFIS) yöntemiyle bir model geliştirilmesi amaçlanmaktadır. Bu kapsamda, Orhaneli termik santralinden elde edilmiş F sınıf uçucu kül beton içerisine çimento ağırlığının % 0-5-10-20 ve 30 oranlarında ikame edilerek 5 farklı beton karışımının her birinden 12 adet deney numunesi hazırlanmıştır. Numunelerin 6 adetinde tahribatsız deneyler diğer numunelerde ise tahribatlı deneyler yapılmıştır. 7. ve 28. günlerde pull-off, ultrases geçiş hızı ve basınç dayanımı deneyleri gerçekleştirilmiştir. ANFIS ile modellemede elde edilen deneysel sonuçlardan 3 tanesi numunedeki vibrasyon hatası nedeniyle elenerek toplam 60 adet deney verisinin 57 tanesi kullanılmıştır. Bu deneysel sonuçlardan beton yaşı, pull-off ve ultrases geçiş hızı geliştirilen modelin girdisi olarak basınç dayanımı ise modelin çıktısı olarak kullanılmıştır. Geliştirilen ANFIS modeli ile tahmin edilen basınç dayanımları gerçek basınç dayanımı değerleri ile karşılaştırılarak modelin tahmin yeteneği test edilmiştir. Sonuç olarak, geliştirilen ANFIS modeli ile tahribatsız test deney sonuçlarıyla eğitilen beton basınç dayanımı değerinin düşük bir hata oranı ile tahmin edebildiği görülmüştür

BULANIK MANTIK VE ISTATISTIKSEL ANALIZ YÖNTEMLERI ILE REVIBRASYON UYGULANMIŞ BETONLARDA BASINÇ DAYANIMI TAHMİNİ

Bu araştırmada, farklı sürelerde revibrasyon uygulanmış betonların basınç dayanımlarının tahmini için regresyon ve bulanık mantık yöntemleri ile iki tahmin modeli geliştirilmiştir. Çalışma kapsamında C 16 sınıfında toplam 50 adet 15x15x15 ebadında küp numune hazırlanmıştır. Hazırlanan numunelere 10 sn süreyle ön vibrasyon uygulanmıştır. Daha sonra 10’ar adet numuneye 30-60-90 ve 120. dakikalarda revibrasyon uygulanmıştır. 10 adet numuneye ise revibrasyon uygulanmamıştır. 28. günde numunelerin birim ağırlıkları ve basınç dayanımları belirlenmiştir. Elde edilen deney sonuçları kullanılarak tahmin modelleri geliştirilmiştir. Regresyon analizi ve bulanık mantık yöntemleriyle geliştirilen tahmin modellerinde basınç dayanımı değerleri revibrasyon süresi ve birim ağırlığa bağlı olarak tahmin edilmiştir. Modellerden elde edilen sonuçlar ile deney sonuçları karşılaştırılmıştır. Geliştirilen modellerin tahmin performansları karşılaştırmalı olarak değerlendirilmiştir. Sonuç olarak revibrasyon uygulanmış betonlarda basınç dayanımının oluşturulan bulanık model ve çoklu lineer regresyon modeli ile tahmin edilmesinin mümkün olduğu, bulanık modelin çoklu lineer regresyona göre beton basınç dayanımını daha düşük bir hata oranıyla tahmin ettiği görülmüştür

Prediction of mechanical properties of cement containing class C fly ash by using artificial neural network and regression technique

WOS: 000265885300011The aim of this study is to investigate the estimation ability of the effects of utilizing different amount of the class C fly ash on the mechanical properties of cement using artificial neural network and regression methods. For this reason, 0, 5, 10, 15 and 20% amount of the class C fly ash were substituted with cement and 40 x 40 x 160 mm dimension specimens were prepared. On the prepared specimens unit weight, flexural tensile strength and compressive strength tests were performed after the 2, 7 and the 28(th) days. 2 different estimation models regression techniques (RT) and the artificial neural network (ANN) methods were used for determining the flexural tensile strength and the compressive strength of the cement specimens. Experimental results were used in the estimation methods. Fly ash content (%), age of specimen (day) and unit weight (g/cm(3)) were used as input parameters and flexural tensile and compressive strengths (N/mm(2)) were used as output parameters. The developed models and the experimental results were compared in the testing data set. As a result, compressive and flexural tensile strength values of mortars containing various amounts class C fly ash can be predicted in a quite short period of time with tiny error rates by using the multilayer feed-forward neural network models than regression techniques

PRODUCTION OF STRUCTURAL LIGHTWEIGHT CONCRETE WITH EXPANDED CLAY AGGREGATE

WOS: 000273608400020In this study, the manufacturing possibility of the high strength lightweight concrete having different amount of the cement by using expanded clay aggregate and its physical and mechanical properties were investigated. For this purpose, concrete mixtures used expanded clay aggregate and natural sand was designed. 0-2, 2-4 and 4-8 mm expanded clay aggregate and 0-2 mm natural sand were used in the concrete mixtures. Three different lightweight concrete having 350, 400 and 450 kg/m(3) amount of the cement were produced. Slump and ve-be tests were performed on the fresh concrete samples and the unit weight, porosity,, compressive strength, split tensile strength and ultrasonic pulse velocity tests were performed on the hardened concrete specimens. As a result, it is seen that production of the structural lightweight concrete having 1,7 kg/m(3) unit weight and 41,27 MPa compressive strength could be possible. Besides the maximum compressive strength and split tensile strength values were obtained from the concrete mixture having 450 kg/m(3) cement dosage

The effects of using fly ash on high strength lightweight concrete produced with expanded clay aggregate

WOS: 000265885300010In this study, the effect of using fly ash in high strength lightweight aggregate concrete produced with expanded clay aggregate on physical and mechanical properties of the concrete was investigated. For this purpose, lightweight concrete mixtures with 350, 400 and 450 kg/m(3) cement content were prepared using expanded clay aggregate. Besides, concretes with 0, 10, 20 and 30% fly ash replacement were produced out of the mixtures with different cement contents. Concrete density, porosity, ultrasonic pulse velocity, compressive and split tensile strength experiments were performed on the prepared samples. As a result, it was seen that it is possible to produce high strength lightweight concrete using expanded clay aggregate; the cement content with 450 kg/m(3) among concrete mixtures had the highest strength values; mechanical properties of concrete could be enhanced by using 10% fly ash; thus a saving in cement amount could be achieved

The effects of using permeable formwork on concrete maturity

Bu araştırmanın amacı; drenaj özelliği bulunan geçirgen kalıp kullanımının beton olgunlaşma sürelerine olan etkisini araştırmaktır. Bu amaçla 20x70x120 cm boyutlarında 4 adet perde duvar kalıbı hazırlanmıştır. Kalıpların bir tanesinde yüzey malzemesi olarak karaçam kerestesi, 3 tanesinde ise plywood kullanılmıştır. Plywood kaplı kalıpların 2 tanesinin yüzeyine drenaj kanal ve delikleri açılmış daha sonra farklı geotekstil astarlarla kaplanmıştır. Diğer plywood yüzeyli kalıp ise referans olarak kullanılmıştır. Kalıplara C30 betonu yerleştirilerek vibratör ile sıkıştırılmıştır. Ayrıca 15x15x15 cm ebadında 16 adet küp numune alınmıştır. Hazırlanan perde duvarların geometrik merkezine ve bir küp numuneye olgunluk ölçer aygıtları yerleştirilmiştir. Diğer küp numunelerin 1., 3., 7., 14., ve 28. günlerde beton basınç dayanımları belirlenmiştir. Sonuç olarak; geçirgen kalıplara dökülmüş betonların, karaçam ve plywood kalıba dökülen betonlara göre olgunluk indekslerinin ortalama %11 oranında büyük olduğu ve daha erken dayanım kazandığı, geçirgen kalıp kullanımı ile beton olgunlaşmasının hızlandırılabileceği görülmüştür.The aim of this study is to investigate the effects of using permeable formwork on concrete maturity. For this purpose, four curtain wall formworks having 120 cm height, 70 cm with and 20 cm thickness; were prepared. As a surface material one Black pine and three plywoods formworks were used. Drainage channels and holes were cut on the surfaces of two of plywoods formworks and the surfaces of these formworks were covered with different geotextile liners. The other polywood formwork selected as reference sample any processing has done. Maturity measuring apparatuses were placed on the geometric centre of the curtain wall formworks. C30 concrete were cast into the prepared formworks and compressed with a vibrator. In addition, 16 number of concrete samples having 15x15x15 cm dimensions were prepared. The maturity measuring device was placed into the one of these samples. And the other samples were waited into the curing pool and the compressive strength of the samples was determined at the 1 {st} ,3{rd}, 7{th}, 14{th}, and 28{th} days respectively. As a result, it is seen that, maturity index of the concrete cast into the permeable formworks is high as 11% than the black pine and plywood formworks and the concrete cast into the permeable formworks were gained earlier strength. Besides, it is seen that, concrete maturity may be accelerated with using permeable formworks

Productıon of structural lıghtweıght concrete wıth expanded clay aggregate

Bu araştırmada genleştirilmiş kil agregası ile farklı çimento dozajlarında taşıyıcı hafif beton üretim olanakları ve betonun mekanik ve fiziksel özelliklerine etkisi araştırılmıştır. Bu amaçla genleştirilmiş kil agregası ve doğal kumun kullanıldığı beton karışımları dizayn edilmiştir. Karışımlarda 0–2, 2–4 ve 4–8 mm boyutlarında genleştirilmiş kil agregası ve 0-2 mm boyutlarında doğal kum kullanılmıştır. Çimento dozajı 350, 400, 450 kg/m3 olan üç farklı hafif beton üretilmiştir. Hazırlanan taze beton karışımlarında slump ve ve-be deneyi, sertleşmiş beton numuneleri üzerinde ise beton yoğunluğu, görünür boşluk oranı, basınç dayanımı yarmada çekme dayanımı ve ultrases geçiş hızı deneyleri gerçekleştirilmiştir. Sonuç olarak, genleştirilmiş kil agregası ile 1,7 kg/m3 gibi düşük bir yoğunluğa sahip basınç dayanımı 41,27 MPa olan taşıyıcı hafif beton elde etmenin mümkün olduğu belirlenmiştir. Üretimi gerçekleştirilen hafif beton karışımlarında 450 kg/m3 çimento dozlu betonların en yüksek basınç ve yarmada çekme dayanımı değerlerine sahip olduğu görülmüştür.In this study, the manufacturing possibility of the high strength lightweight concrete having different amount of the cement by using expanded clay aggregate and its physical and mechanical properties were investigated. For this purpose, concrete mixtures used expanded clay aggregate and natural sand was designed. 0–2, 2–4 and 4–8 mm expanded clay aggregate and 0-2 mm natural sand were used in the concrete mixtures. Three different lightweight concrete having 350, 400 and 450 kg/m³ amount of the cement were produced. Slump and ve-be tests were performed on the fresh concrete samples and the unit weight, porosity,, compressive strength, split tensile strength and ultrasonic pulse velocity tests were performed on the hardened concrete specimens. As a result, it is seen that production of the structural lightweight concrete having 1,7 kg/m³ unit weight and 41,27 MPa compressive strength could be possible. Besides the maximum compressive strength and split tensile strength values were obtained from the concrete mixture having 450 kg/m³ cement dosage

Effect of The Filler Type and Particle Distribution Changes on Polyester Matrix Composites

In this study, the effect of the usage of additives at different initiator ratios as well as the usage of fillers of different types and different grain distributions on resin consumption and compressive strength of polyester matrix composites were investigated. Orthophthalic unsaturated polyester resin (UP) was used as a matrix. The initiator (methyl ethyl ketone peroxide) at the ratio of 1.0%, 1.5%, and 2.0% and the accelerator (cobalt octoate) at the ratio of 1.0% by weight was used to start the polymerization. Silica, basalt, and quartz sand were used as the filler type. All fillings used in the study were prepared in the grain size distribution of the American Foundry Society (AFS 40-45) and in the grain size distribution determined by reference to the Fuller equation (F 1.0). Resin consumption and pressure resistances of produced composites were determined, and SEM analyses were carried out. As a result of the study, in all filled composites, the minimum resin consumption was achieved at a starting rate of 1.0%. The highest compressive strength was determined as 130.43 MPa in the basalt filled composite and in the AFS40-45 grain distribution