Mühendislik Bilimleri ve Tasarım Dergisi, Dec 29, 2023
Vakum Yalıtım Panelleri (VYP), ısı kayıplarının azaltılmasında kullanılan ve geleneksel yalıtım m... more Vakum Yalıtım Panelleri (VYP), ısı kayıplarının azaltılmasında kullanılan ve geleneksel yalıtım malzemelerine kıyasla çok daha düşük ısı iletkenlik katsayısına sahip yeni nesil yalıtım malzemelerdir. Isı iletkenlik katsayıları ~3-7 mWm -1 K -1 aralığında ve kalınlıkları geleneksel yalıtım malzemelerine göre 5-10 kat daha ince olabilmektedir. VYP'lerin, çekirdek malzemesi geçirimsiz bir bariyer içerisinde vakumlanır. Vakum sonrası panel üzerine uygulanan atmosfer basıncı ~10 ton/m 2 seviyesindedir. Dolayısıyla çekirdeğin fiziksel ve mekanik özellikleri, boyutsal kararlılık açısından çok önemlidir. Yeterli mekanik özelliklere sahip olmayan çekirdekler vakumlandıktan sonra çöker ve rijit bir panel elde edilemez. Bu çalışmada, fumed silika (FS) ve alternatif tozların karışımı ile üretilen çekirdeklerin mekanik ve fiziksel özelliklerinin belirlenmesi amaçlanmıştır. Bu amaç doğrultusunda, çekirdek üretiminde beş farklı özgül yüzey alanına (ÖYA) sahip nano ve mikro boyutta tozlar kullanılmıştır. Ayrıca karışıma %5, %10 ve %15 oranlarında cam elyafı (fiber) eklenmiştir. Karışım oranları belirlendikten sonra 20-50 kN aralığında sıkıştırma kuvvetleri uygulanarak farklı fiziksel ve mekanik özellikte 45 çekirdek panel üretilmiştir. Çekirdeklerin fiziksel ve mekanik özellikleri DIN EN 1602, DIN EN 826, DIN EN 1607 standartlarına göre test edilmiştir. Elde edilen bulgular değerlendirildiğinde, çekirdek tasarımında ≤%10 fiber ilavesi ve yüksek ÖYA'na sahip tozların çekirdek boyutsal kararlılığını ve elastisite modülünü arttırdığı tespit edilmiştir. Sonuç olarak DIN EN standartlarına göre en uygun mekanik özellikleri CP-1-4 çekirdeği sağlamıştır.
Journal of Thermal Analysis and Calorimetry, Jan 14, 2020
The reduction of radiation heat transfer in VIPs is an important issue. In VIPs, the radiation he... more The reduction of radiation heat transfer in VIPs is an important issue. In VIPs, the radiation heat transfer is reduced by the use of opacifier. However, the amount of opacifier also significantly affects the cost of VIP. In this study, the effect of different types and sizes of opacifiers on VIP thermal conductivity was investigated. For this purpose, 6 VIP samples containing different opacifiers (SiC, graphite and calcium aluminate in 3 different grain sizes) were produced. Fumed silica, glass fiber and opacifier were used as fillers in VIP cores at 65%, 20% and 15% (by mass), respectively. VIP samples were vacuumed up to 0.1 Pa, and their thermal conductivity coefficients were measured according to TS EN 12667 standard. In addition, transmittance ratios (%T) of fumed silica, glass fiber, opacifiers and core samples were measured by FTIR spectrophotometer and the mass extinction coefficients of each sample were calculated. The silicon carbide (F1000) as the opacifier (e: 399 m 2 kg −1) and the graphite-containing core among the VIP core samples (e: 149 m 2 kg −1) exhibited the highest mass absorption coefficient. In addition, the thermal conductivity of the core samples without barrier was measured under 1 Pa vacuum and then the radiation conductivities were calculated from the obtained data. F800 type SiC significantly reduced radiation heat transfer, while the solid conduction of the core was increased due to its relatively coarse grain size. VIP sample with SiC (F1200) provided the lowest thermal conductivity at 0.1 Pa (3.94 mW mK −1). As a result, F1200 type SiC was found to be the most efficient type of opacifier among the investigated opacifiers.
Vacuum insulation panels have higher efficient materials than the insulation materials which have... more Vacuum insulation panels have higher efficient materials than the insulation materials which have known their heat insulation properties. Heat insulation could be provided by vacuum insulation panels ten times according to conventional insulation materials. The most important difficulty of growing up for vacuum insulation panels is high production costs at present. When this situation was analyzed, it is known that core materials are most important elements which affect to cost. Production of core material at more economical conditions will reduce vacuum insulation panels' production costs significantly, and then VIP's usage will be growing up increasingly. Expansion of applications brings about energy efficiency and economy and will create significant added value to Turkey's economy, in addition this it will be more positive contribution to the environment. VIP is not widely used as insulating material in our country. The main reasons for this situation, VIP"s are unknown, its core can't produce domestically, and its imports are not economical for using in industrial. In addition, scientific researches and studies have been limited about VIP. Using of the VIP will become widespread in our country with the production of economic core. Wide spreading of the application will provide energy efficiency and conservation. In addition the country's economy will create significant added value, energy conservation will also be a very positive contribution to the environment. In this paper, scientific research findings about VIP's physical, structural, performance characteristics and production methods of VIP have been presented in summary so far in order to contribute to the scientific and industrial research. VIP's performance and costs have been compared with conventional thermal insulation materials.
Arabian journal for science and engineering, Feb 5, 2016
Vacuum insulation panels (VIPs) provide high thermal resistances properties that can enhance the ... more Vacuum insulation panels (VIPs) provide high thermal resistances properties that can enhance the energy efficiency of the insulating systems and provide savings in energy consumption. They are generally made with porous core materials wrapped, under vacuum, in airtight barrier films. The properties of the core materials have big effect on the thermal insulation performance and mechanical properties of the VIPs. In this study, a novel VIP core formulation was developed by using a nano-powder, fiber and opacifier at different ratios. The VIP samples at various compression pressures with different vacuum levels were produced by using the obtained core formulations. Moreover, the relationship between compression pressure and density of VIP core samples was investigated; thermal conductivities of the samples were measured according to heat flow meter method at atmospheric and 0.1 mbar pressure levels. The findings were analyzed by using Datafit 7.1 software. As a result, the optimum fiber and opacifier ratio were determined as 13–20 and 15 %, respectively, for VIP prototypes obtained by using fumed silica (220 $${{\rm m}^2/{\rm g}}$$m2/g), glass fiber (avg. diameter; $${10\,\mu {\rm m}}$$10μm) and silicon carbide (575 $${{\rm cm}^2/{\rm g}}$$cm2/g). Furthermore, the effect of fiber and opacifier ratios on the VIP core densities was investigated and various equations were developed to estimate the thermal conductivity values of VIPs at atmospheric and 0.1 mbar pressure levels.
Kalsiyum alüminat çimentosu yol uygulamaları, endüstriyel zemin uygulamaları, yüksek sıcaklık dir... more Kalsiyum alüminat çimentosu yol uygulamaları, endüstriyel zemin uygulamaları, yüksek sıcaklık direnci gerektiren refrakter uygulamaları vb. gibi durumlarda üstün performans göstermektedir. Bu çalışmada, hidrojen peroksit, hidrojen peroksit +2mm genleştirilmiş perlit ve yalnızca köpük kullanımıyla olmak üzere, 3 farklı yöntemle kalsiyum alüminat çimentolu hafif beton numuneleri üretilmiştir. Hafif beton karışımları 4040160 mm prizma ve 6025 mm ölçülerinde silindirik kalıplara dökülmüş ve kalıptan çıkarıldıktan sonra 23 C ve % 90 bağıl nemde kürlenmiştir. Sertleşmiş hafif beton numuneleri üzerinde kuru birim hacim kütle, eğilme-basınç dayanımı, kapiler su emme ve ısıl iletkenlik deneyleri yürütülmüştür. Ayrıca hidrojen peroksit kullanım oranı, genleşmiş perlit kullanım oranı vd. karışım parametrelerinin numune fiziko-mekanik özelliklerine etkileri analiz edilmiştir. Deney sonuçlarından elde edilen bulgular ışığında hafif beton numunelerinin fizikomekanik özellikleri karşılaştırılmış ve optimum özelliğe sahip numune türü belirlenmiştir. Sonuç olarak bu çalışma kapsamında kalsiyum alüminat çimentosuyla kuru yoğunluğu: 269-348 kg/m 3 , basınç dayanımı: 245-464 kPa, eğilme dayanımı: 155-375 kPa ve ısıl iletkenliği 0.068-0.092 W/mK özelliklerine sahip hafif beton numuneleri üretimi gerçekleştirilmiştir.
Bu çalışmanın amacı, yüksek yalıtım performansına sahip nano toz dolgulu çekirdek numunelerinin f... more Bu çalışmanın amacı, yüksek yalıtım performansına sahip nano toz dolgulu çekirdek numunelerinin fiziko-mekanik özelliklerinin belirlenmesidir. Çalışmada çekirdek numunelerinin basınç dayanımı, çekme dayanımı, elastisite modülü gibi mekanik özellikler ile yoğunluk ve porozite gibi fiziksel özellikleri araştırılmıştır. 4 farklı fiber oranında ve 3 farklı sıkıştırma kuvveti seviyesinde toplam 12 adet opaklaştırıcısız çekirdek numunesi üretilmiştir. Bu numunelerin üretiminde 2 kN, 2.5 kN ve 3.0 kN sıkışma kuvvetleri uygulanmıştır. Bu durumda numunelerin sıkıştırılmasında oluşan en yüksek gerilme değerleri (σ maks) ve bu gerilme değerleri esas alınarak çekirdek panel üretiminde uygulanacak sıkışma kuvvetleri (F P) hesaplanmıştır. Sonuç olarak çekirdek numunesi içerisinde fiber içeriği arttıkça genel olarak %10 deformasyonda basınç dayanımı azaldığı görülmüştür. Çekme dayanımları açısından en uygun fiber oranı ise %15 olarak belirlenmiştir.
Science and engineering of composite materials, Dec 1, 2009
Deformations named as autogenous (chemical + autogenous) shrinkage related to parameters of cemen... more Deformations named as autogenous (chemical + autogenous) shrinkage related to parameters of cement dosage, water/cement ratio etc. in high performance concretes are studied. Prevention of autogenous shrinkage with outer water curing is not possible. In this research, the effects of three different lightweight aggregate types used as internal water reservoir in high performance concrete were analyzed on shrinkage, hydration degree and strength properties in different curing media. The research findings show that-1/+2 mm saturated lightweight aggregates in concrete samples of 40% relative humidity medium reduce the autogenous shrinkage, improve the hydration degree and increase the compressive strength.
ABSTRACT Concrete, which is the most consumption material after the water in the world, sustains ... more ABSTRACT Concrete, which is the most consumption material after the water in the world, sustains a very big importance in terms of durability, strength, safety, economy and environment. The utilizing lifetime of concrete structures with large volumes which are finished before it was planned may required highly costs for restoration, reinforcement or rebuilding. The one of significant concerns at designs of durable concretes is alkali silica reaction (ASR). The capillary cracks have formed by ASR increases to permeability of concrete, reduces the strength and lowers the economic lifetime of concrete. In this paper, a comprehensive experimental research was carried out to prevent the damages to be able to improve in the reactive aggregated concrete structures by using the natural (micronised) amorphous silica in the mixtures. Furthermore, the engineering properties of amorphous silica, comparison with the other types of mineral additives and the test methodology used in the research were presented and the research findings were also discussed. The usage of amorphous silica as a mineral admixture in concrete has reduced up to 120% level of ASR expansion.
Nowadays, in order to produce the high strength concrete in the civil engineering applications, t... more Nowadays, in order to produce the high strength concrete in the civil engineering applications, the use of different types of admixtures is well-known. In general, these materials are either chemical or mineral products. In this paper, the formations of amorphous silica of Isparta Region are defined in a technical manner and their use in the concrete manufacturing as a natural pozzolan is evaluated. The effectiveness of amorphous silica in making high strength concrete material is analysed experimentally, and the research findings are discussed.
This study investigated the production potential of foam glass having an apparent density of <... more This study investigated the production potential of foam glass having an apparent density of < 200 kgm−3 from waste glass powders ground to a grain size < 150 µm. In the study, glass powders obtained from waste window glass and waste soda bottles were used as fillers, and sodium silicate, silicon carbide, manganese oxide, calcium carbonate, activated carbon and glycerin were used as foaming agents. The samples were sintered in an ash oven at 875 °C for 25 min and then cooled at 10 °C/min. The volumes of the foam glass samples obtained were determined, their masses were measured with precision scales, and then, their densities were calculated. The pore diameters and morphology of the samples were examined by scanning electron microscopy (SEM). The compressive strengths of the foam glass samples were tested, and their thermal conductivity coefficients were measured using the heat flow meter method. As a result, the chemical structure of the waste glass, the optimum amount of foaming additives and their proportions were determined for the production of ultra-light foam glass.
Vacuum insulation panels have higher efficient materials than the insulation materials which have... more Vacuum insulation panels have higher efficient materials than the insulation materials which have known their heat insulation properties. Heat insulation could be provided by vacuum insulation panels ten times according to conventional insulation materials. The most important difficulty of growing up for vacuum insulation panels is high production costs at present. When this situation was analyzed, it is known that core materials are most important elements which affect to cost. Production of core material at more economical conditions will reduce vacuum insulation panels’ production costs significantly, and then VIP’s usage will be growing up increasingly. Expansion of applications brings about energy efficiency and economy and will create significant added value to Turkey’s economy, in addition this it will be more positive contribution to the environment. VIP is not widely used as insulating material in our country. The main reasons for this situation, VIP‟s are unknown, its core...
In this study, the effects of using andesite powder wastes-produced from natural stone factories ... more In this study, the effects of using andesite powder wastes-produced from natural stone factories as mineral additives in concrete manufacturing-on the compressive strength of concrete were modeled using an Artificial Neural Network (ANN). To achieve this, cement mixtures were produced by using waste andesite powder (WAP) mixture at ratios of 0% (control), 10%, 15% and 20%. The effects of curing time were investigated by preparing specimens at 28 and 90 days. The training set was formed by using cement and the specified WAP mixtures and curing time parameters. It was observed that the results obtained from the training ANNs were consistent with the experimental data.
The use of boron compounds as composites of cementitious, except for the limited usage conditions... more The use of boron compounds as composites of cementitious, except for the limited usage conditions like setting retarder has not become widespread because of the hardening and the related problems. In this study, the effects of the boron compounds into hydration process of the different cement types and controllability of these effects was investigated. Portland cement, boron modified active belite cement, and calcium aluminate cement were used in the mortar mixtures as binder material. Except for the control mixture, boric acid (BA) was used at the ratios of 0.25-1.00% of weight of cement in mortar mixtures with Portland cement. Setting times dependent on pH, EC and T changes of fresh mortars were measured. With increasing BA concentration, setting times of the mortars rather increased, pH, electrical conductivity, and T values of the mortars significantly reduced. To suppress the affect of BA on the hydration process, the two various stabilizers were used in the mortars, setting times, pH, electrical conductivity, and T values of these mortars were measured again. As a result, the optimum workability times and the parameters of the hydration reaction taking into account, the most suitable type and usage ratio of stabilizer were determined for mortars with BA.
Artificial neural network is generally information processing system and a computer program that ... more Artificial neural network is generally information processing system and a computer program that imitates human brain neural network system. By entering the information from outside, artificial neural network can be trained on examples related to a problem, so that modeling of the problem is provided. In this study, compressive strength, Poisson ratio of the lightweight concrete specimens, which have different natural lightweight aggregates, were modeled with artificial neural network. The data which were provided by artificial neural network model were compared with the data obtained from experimental study and a good agreement was determined between the results.
Mühendislik Bilimleri ve Tasarım Dergisi, Dec 29, 2023
Vakum Yalıtım Panelleri (VYP), ısı kayıplarının azaltılmasında kullanılan ve geleneksel yalıtım m... more Vakum Yalıtım Panelleri (VYP), ısı kayıplarının azaltılmasında kullanılan ve geleneksel yalıtım malzemelerine kıyasla çok daha düşük ısı iletkenlik katsayısına sahip yeni nesil yalıtım malzemelerdir. Isı iletkenlik katsayıları ~3-7 mWm -1 K -1 aralığında ve kalınlıkları geleneksel yalıtım malzemelerine göre 5-10 kat daha ince olabilmektedir. VYP'lerin, çekirdek malzemesi geçirimsiz bir bariyer içerisinde vakumlanır. Vakum sonrası panel üzerine uygulanan atmosfer basıncı ~10 ton/m 2 seviyesindedir. Dolayısıyla çekirdeğin fiziksel ve mekanik özellikleri, boyutsal kararlılık açısından çok önemlidir. Yeterli mekanik özelliklere sahip olmayan çekirdekler vakumlandıktan sonra çöker ve rijit bir panel elde edilemez. Bu çalışmada, fumed silika (FS) ve alternatif tozların karışımı ile üretilen çekirdeklerin mekanik ve fiziksel özelliklerinin belirlenmesi amaçlanmıştır. Bu amaç doğrultusunda, çekirdek üretiminde beş farklı özgül yüzey alanına (ÖYA) sahip nano ve mikro boyutta tozlar kullanılmıştır. Ayrıca karışıma %5, %10 ve %15 oranlarında cam elyafı (fiber) eklenmiştir. Karışım oranları belirlendikten sonra 20-50 kN aralığında sıkıştırma kuvvetleri uygulanarak farklı fiziksel ve mekanik özellikte 45 çekirdek panel üretilmiştir. Çekirdeklerin fiziksel ve mekanik özellikleri DIN EN 1602, DIN EN 826, DIN EN 1607 standartlarına göre test edilmiştir. Elde edilen bulgular değerlendirildiğinde, çekirdek tasarımında ≤%10 fiber ilavesi ve yüksek ÖYA'na sahip tozların çekirdek boyutsal kararlılığını ve elastisite modülünü arttırdığı tespit edilmiştir. Sonuç olarak DIN EN standartlarına göre en uygun mekanik özellikleri CP-1-4 çekirdeği sağlamıştır.
Journal of Thermal Analysis and Calorimetry, Jan 14, 2020
The reduction of radiation heat transfer in VIPs is an important issue. In VIPs, the radiation he... more The reduction of radiation heat transfer in VIPs is an important issue. In VIPs, the radiation heat transfer is reduced by the use of opacifier. However, the amount of opacifier also significantly affects the cost of VIP. In this study, the effect of different types and sizes of opacifiers on VIP thermal conductivity was investigated. For this purpose, 6 VIP samples containing different opacifiers (SiC, graphite and calcium aluminate in 3 different grain sizes) were produced. Fumed silica, glass fiber and opacifier were used as fillers in VIP cores at 65%, 20% and 15% (by mass), respectively. VIP samples were vacuumed up to 0.1 Pa, and their thermal conductivity coefficients were measured according to TS EN 12667 standard. In addition, transmittance ratios (%T) of fumed silica, glass fiber, opacifiers and core samples were measured by FTIR spectrophotometer and the mass extinction coefficients of each sample were calculated. The silicon carbide (F1000) as the opacifier (e: 399 m 2 kg −1) and the graphite-containing core among the VIP core samples (e: 149 m 2 kg −1) exhibited the highest mass absorption coefficient. In addition, the thermal conductivity of the core samples without barrier was measured under 1 Pa vacuum and then the radiation conductivities were calculated from the obtained data. F800 type SiC significantly reduced radiation heat transfer, while the solid conduction of the core was increased due to its relatively coarse grain size. VIP sample with SiC (F1200) provided the lowest thermal conductivity at 0.1 Pa (3.94 mW mK −1). As a result, F1200 type SiC was found to be the most efficient type of opacifier among the investigated opacifiers.
Vacuum insulation panels have higher efficient materials than the insulation materials which have... more Vacuum insulation panels have higher efficient materials than the insulation materials which have known their heat insulation properties. Heat insulation could be provided by vacuum insulation panels ten times according to conventional insulation materials. The most important difficulty of growing up for vacuum insulation panels is high production costs at present. When this situation was analyzed, it is known that core materials are most important elements which affect to cost. Production of core material at more economical conditions will reduce vacuum insulation panels' production costs significantly, and then VIP's usage will be growing up increasingly. Expansion of applications brings about energy efficiency and economy and will create significant added value to Turkey's economy, in addition this it will be more positive contribution to the environment. VIP is not widely used as insulating material in our country. The main reasons for this situation, VIP"s are unknown, its core can't produce domestically, and its imports are not economical for using in industrial. In addition, scientific researches and studies have been limited about VIP. Using of the VIP will become widespread in our country with the production of economic core. Wide spreading of the application will provide energy efficiency and conservation. In addition the country's economy will create significant added value, energy conservation will also be a very positive contribution to the environment. In this paper, scientific research findings about VIP's physical, structural, performance characteristics and production methods of VIP have been presented in summary so far in order to contribute to the scientific and industrial research. VIP's performance and costs have been compared with conventional thermal insulation materials.
Arabian journal for science and engineering, Feb 5, 2016
Vacuum insulation panels (VIPs) provide high thermal resistances properties that can enhance the ... more Vacuum insulation panels (VIPs) provide high thermal resistances properties that can enhance the energy efficiency of the insulating systems and provide savings in energy consumption. They are generally made with porous core materials wrapped, under vacuum, in airtight barrier films. The properties of the core materials have big effect on the thermal insulation performance and mechanical properties of the VIPs. In this study, a novel VIP core formulation was developed by using a nano-powder, fiber and opacifier at different ratios. The VIP samples at various compression pressures with different vacuum levels were produced by using the obtained core formulations. Moreover, the relationship between compression pressure and density of VIP core samples was investigated; thermal conductivities of the samples were measured according to heat flow meter method at atmospheric and 0.1 mbar pressure levels. The findings were analyzed by using Datafit 7.1 software. As a result, the optimum fiber and opacifier ratio were determined as 13–20 and 15 %, respectively, for VIP prototypes obtained by using fumed silica (220 $${{\rm m}^2/{\rm g}}$$m2/g), glass fiber (avg. diameter; $${10\,\mu {\rm m}}$$10μm) and silicon carbide (575 $${{\rm cm}^2/{\rm g}}$$cm2/g). Furthermore, the effect of fiber and opacifier ratios on the VIP core densities was investigated and various equations were developed to estimate the thermal conductivity values of VIPs at atmospheric and 0.1 mbar pressure levels.
Kalsiyum alüminat çimentosu yol uygulamaları, endüstriyel zemin uygulamaları, yüksek sıcaklık dir... more Kalsiyum alüminat çimentosu yol uygulamaları, endüstriyel zemin uygulamaları, yüksek sıcaklık direnci gerektiren refrakter uygulamaları vb. gibi durumlarda üstün performans göstermektedir. Bu çalışmada, hidrojen peroksit, hidrojen peroksit +2mm genleştirilmiş perlit ve yalnızca köpük kullanımıyla olmak üzere, 3 farklı yöntemle kalsiyum alüminat çimentolu hafif beton numuneleri üretilmiştir. Hafif beton karışımları 4040160 mm prizma ve 6025 mm ölçülerinde silindirik kalıplara dökülmüş ve kalıptan çıkarıldıktan sonra 23 C ve % 90 bağıl nemde kürlenmiştir. Sertleşmiş hafif beton numuneleri üzerinde kuru birim hacim kütle, eğilme-basınç dayanımı, kapiler su emme ve ısıl iletkenlik deneyleri yürütülmüştür. Ayrıca hidrojen peroksit kullanım oranı, genleşmiş perlit kullanım oranı vd. karışım parametrelerinin numune fiziko-mekanik özelliklerine etkileri analiz edilmiştir. Deney sonuçlarından elde edilen bulgular ışığında hafif beton numunelerinin fizikomekanik özellikleri karşılaştırılmış ve optimum özelliğe sahip numune türü belirlenmiştir. Sonuç olarak bu çalışma kapsamında kalsiyum alüminat çimentosuyla kuru yoğunluğu: 269-348 kg/m 3 , basınç dayanımı: 245-464 kPa, eğilme dayanımı: 155-375 kPa ve ısıl iletkenliği 0.068-0.092 W/mK özelliklerine sahip hafif beton numuneleri üretimi gerçekleştirilmiştir.
Bu çalışmanın amacı, yüksek yalıtım performansına sahip nano toz dolgulu çekirdek numunelerinin f... more Bu çalışmanın amacı, yüksek yalıtım performansına sahip nano toz dolgulu çekirdek numunelerinin fiziko-mekanik özelliklerinin belirlenmesidir. Çalışmada çekirdek numunelerinin basınç dayanımı, çekme dayanımı, elastisite modülü gibi mekanik özellikler ile yoğunluk ve porozite gibi fiziksel özellikleri araştırılmıştır. 4 farklı fiber oranında ve 3 farklı sıkıştırma kuvveti seviyesinde toplam 12 adet opaklaştırıcısız çekirdek numunesi üretilmiştir. Bu numunelerin üretiminde 2 kN, 2.5 kN ve 3.0 kN sıkışma kuvvetleri uygulanmıştır. Bu durumda numunelerin sıkıştırılmasında oluşan en yüksek gerilme değerleri (σ maks) ve bu gerilme değerleri esas alınarak çekirdek panel üretiminde uygulanacak sıkışma kuvvetleri (F P) hesaplanmıştır. Sonuç olarak çekirdek numunesi içerisinde fiber içeriği arttıkça genel olarak %10 deformasyonda basınç dayanımı azaldığı görülmüştür. Çekme dayanımları açısından en uygun fiber oranı ise %15 olarak belirlenmiştir.
Science and engineering of composite materials, Dec 1, 2009
Deformations named as autogenous (chemical + autogenous) shrinkage related to parameters of cemen... more Deformations named as autogenous (chemical + autogenous) shrinkage related to parameters of cement dosage, water/cement ratio etc. in high performance concretes are studied. Prevention of autogenous shrinkage with outer water curing is not possible. In this research, the effects of three different lightweight aggregate types used as internal water reservoir in high performance concrete were analyzed on shrinkage, hydration degree and strength properties in different curing media. The research findings show that-1/+2 mm saturated lightweight aggregates in concrete samples of 40% relative humidity medium reduce the autogenous shrinkage, improve the hydration degree and increase the compressive strength.
ABSTRACT Concrete, which is the most consumption material after the water in the world, sustains ... more ABSTRACT Concrete, which is the most consumption material after the water in the world, sustains a very big importance in terms of durability, strength, safety, economy and environment. The utilizing lifetime of concrete structures with large volumes which are finished before it was planned may required highly costs for restoration, reinforcement or rebuilding. The one of significant concerns at designs of durable concretes is alkali silica reaction (ASR). The capillary cracks have formed by ASR increases to permeability of concrete, reduces the strength and lowers the economic lifetime of concrete. In this paper, a comprehensive experimental research was carried out to prevent the damages to be able to improve in the reactive aggregated concrete structures by using the natural (micronised) amorphous silica in the mixtures. Furthermore, the engineering properties of amorphous silica, comparison with the other types of mineral additives and the test methodology used in the research were presented and the research findings were also discussed. The usage of amorphous silica as a mineral admixture in concrete has reduced up to 120% level of ASR expansion.
Nowadays, in order to produce the high strength concrete in the civil engineering applications, t... more Nowadays, in order to produce the high strength concrete in the civil engineering applications, the use of different types of admixtures is well-known. In general, these materials are either chemical or mineral products. In this paper, the formations of amorphous silica of Isparta Region are defined in a technical manner and their use in the concrete manufacturing as a natural pozzolan is evaluated. The effectiveness of amorphous silica in making high strength concrete material is analysed experimentally, and the research findings are discussed.
This study investigated the production potential of foam glass having an apparent density of <... more This study investigated the production potential of foam glass having an apparent density of < 200 kgm−3 from waste glass powders ground to a grain size < 150 µm. In the study, glass powders obtained from waste window glass and waste soda bottles were used as fillers, and sodium silicate, silicon carbide, manganese oxide, calcium carbonate, activated carbon and glycerin were used as foaming agents. The samples were sintered in an ash oven at 875 °C for 25 min and then cooled at 10 °C/min. The volumes of the foam glass samples obtained were determined, their masses were measured with precision scales, and then, their densities were calculated. The pore diameters and morphology of the samples were examined by scanning electron microscopy (SEM). The compressive strengths of the foam glass samples were tested, and their thermal conductivity coefficients were measured using the heat flow meter method. As a result, the chemical structure of the waste glass, the optimum amount of foaming additives and their proportions were determined for the production of ultra-light foam glass.
Vacuum insulation panels have higher efficient materials than the insulation materials which have... more Vacuum insulation panels have higher efficient materials than the insulation materials which have known their heat insulation properties. Heat insulation could be provided by vacuum insulation panels ten times according to conventional insulation materials. The most important difficulty of growing up for vacuum insulation panels is high production costs at present. When this situation was analyzed, it is known that core materials are most important elements which affect to cost. Production of core material at more economical conditions will reduce vacuum insulation panels’ production costs significantly, and then VIP’s usage will be growing up increasingly. Expansion of applications brings about energy efficiency and economy and will create significant added value to Turkey’s economy, in addition this it will be more positive contribution to the environment. VIP is not widely used as insulating material in our country. The main reasons for this situation, VIP‟s are unknown, its core...
In this study, the effects of using andesite powder wastes-produced from natural stone factories ... more In this study, the effects of using andesite powder wastes-produced from natural stone factories as mineral additives in concrete manufacturing-on the compressive strength of concrete were modeled using an Artificial Neural Network (ANN). To achieve this, cement mixtures were produced by using waste andesite powder (WAP) mixture at ratios of 0% (control), 10%, 15% and 20%. The effects of curing time were investigated by preparing specimens at 28 and 90 days. The training set was formed by using cement and the specified WAP mixtures and curing time parameters. It was observed that the results obtained from the training ANNs were consistent with the experimental data.
The use of boron compounds as composites of cementitious, except for the limited usage conditions... more The use of boron compounds as composites of cementitious, except for the limited usage conditions like setting retarder has not become widespread because of the hardening and the related problems. In this study, the effects of the boron compounds into hydration process of the different cement types and controllability of these effects was investigated. Portland cement, boron modified active belite cement, and calcium aluminate cement were used in the mortar mixtures as binder material. Except for the control mixture, boric acid (BA) was used at the ratios of 0.25-1.00% of weight of cement in mortar mixtures with Portland cement. Setting times dependent on pH, EC and T changes of fresh mortars were measured. With increasing BA concentration, setting times of the mortars rather increased, pH, electrical conductivity, and T values of the mortars significantly reduced. To suppress the affect of BA on the hydration process, the two various stabilizers were used in the mortars, setting times, pH, electrical conductivity, and T values of these mortars were measured again. As a result, the optimum workability times and the parameters of the hydration reaction taking into account, the most suitable type and usage ratio of stabilizer were determined for mortars with BA.
Artificial neural network is generally information processing system and a computer program that ... more Artificial neural network is generally information processing system and a computer program that imitates human brain neural network system. By entering the information from outside, artificial neural network can be trained on examples related to a problem, so that modeling of the problem is provided. In this study, compressive strength, Poisson ratio of the lightweight concrete specimens, which have different natural lightweight aggregates, were modeled with artificial neural network. The data which were provided by artificial neural network model were compared with the data obtained from experimental study and a good agreement was determined between the results.
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Papers by Metin DAVRAZ