Investigation of the effect of silica fume and synthetic foam additive on cell structure in ultra-low density foam concrete

In this study, the properties of ultra-low density foam concrete with silica fume substitute and synthetic foam additive were investigated. Two different references and silica fume substituted foam concretes with densities of 220 and 200 kg/m(3) were produced. Silica fume was used as the replacement material and its ratio in the mixtures was kept constant at 5% by weight. According to the results of the study, the compressive strengths and the thermal conductivity coefficients of the references and silica fume substituted foam concretes with densities of 220 and 200 kg/m(3) were found to be 0.26, 0.21 and 0.32, 0.26 Mpa at 28 days and 0.073, 0.069 and 0.068, 0.060 W/mK, respectively. In addition, the behavior of foam concrete at high temperatures was investigated using a flame source, which can reach up to 1200 degrees C, since temperatures usually exceed 1000 degrees C during a fire. At the end of ten minutes, the heat permeability of silica fume substituted foam concrete exposed to a 1200 degrees C temperature was 6.5% and 5.3%, which was better than reference foam concretes, respectively. As a result, silica fume has positively affected the compressive strength at later ages and thermal conductivity properties of foam concrete

Investigation of Cement, Mineral and Chemical Additive Interactions in Micro Scales

Self-compacting concretes (SCC), a new type of concrete, were realized with the development of polycarboxylate-based chemical additives. The interaction of these additives with the powder materials in the nano and micro scales affects the fresh and hardened properties of concrete in meso and macro scales. To change and improve the macro-dimensional properties of concrete, it is necessary to better analyze the nano-micro-dimensional interaction. The aim of this study is to examine the interactions of cement, mineral and chemical additives in micro scale. For this purpose, the zeta potential values of the mixtures consisting of cement, water, calcite and blast furnace slag prepared by using a polycarboxylate based plasticizer additive were analyzed. In addition, SEM analyzes of hardened samples were made on the 28th days

Investigation of the Effect of Geometric Shape and Ratio of Steel Fibers on Concrete Properties

Birçok araştırmada betonun teknik özelliklerini artırmak için farklı cins ve tiplerdeki liflerle çalışmalar yapılmıştır. Genellikle sonyıllarda betonun mekanik özeliklerinin öncelikli olan yerlerde çelik lif tercih edilmektedir. Bu çalışmada, tarafımızca şekil verilerekoluşturulan 2 farklı çelik lif tipi (Z, C şeklinde) ve 80/60 çelik lifi, çimento ağılığının 0.0, 0.10, 0.15 ve 0.20 oranlarındakullanılmıştır. Bu farklı şekillere sahip çelik liflerin, taze betonda oluşturdukları hava %’si miktarı ve işlenebilme özelliğigözlenirken; sertleşmiş betonda ise basınç, eğilme ve aşınma dayanımlarına olan etkileri incelenmiştir. Lifin şekli ve oranının, tazeve sertleşmiş beton özellikleri üzerinde etkili olduğu görülmüştür. Taze ve sertleşmiş betonda en optimum özellik, 80/60 lifinin%10 kullanılmasıyla elde edilmiştir.Many studies have been conducted with fibers of different types and shapes to increase the technical properties of concrete. Generally, steel fiber has been preferred in the places where the mechanical properties of concrete have priority in recent years. In this study, 2 different steel fiber types (Z, C shaped) and 80/60 steel fiber, which are formed by us, were used in the ratios of cement weights at 0.0, 0.10, 0.15 and 0.20. While the amount of air content and the workability of the steel fibers of these different shapes added in fresh concrete were observed; In hardened concrete, its effects on compressive strength, flexural strength and abrasion resistance were investigated. The shape and ratio of the fiber have been shown to be effective on fresh and hardened concrete properties. The optimum feature in fresh and hardened concrete has been achieved by using 10% of 80/60 fiber

Usıng Nano Modıfıed Cement Based Composıtes Incorporatıng Hıgh Volume Fly Ash As A Concrete Repaır Materıal

Alt yapı elemanlarının tekrarlı mekanik ve çevresel yükler altında hasar görmesine veya bozulmasına sık rastlanmaktadır. Bozulan bu yapıların tekrar onarılması, çevresel ve ekonomik açıdan ciddi sorunlar ortaya çıkarmaktadır. Son yıllarda yüksek performanslı lif donatılı çimento esaslı kompozitlerin (YPLDÇK), onarım ve güçlendirme işlerinde başarılı bir şekilde kullanılabileceği gözlemlenmiştir. YPLDÇK' ların üretiminde mikro-mekanik tabanlı tasarım kriterleri nedeni ile yüksek hacimde uçucu kül kullanımı neredeyse bir gereksinim olmaya başlamıştır. Yüksek hacimli uçucu kül içeren YPLDÇK özellikle önemli beton yol vb. gibi betonarme altyapıların onarım işlerinde kullanılabilmesi için erken yaş yüksek dayanıma sahip olması ve aynı anda boyutsal kararlılığının yüksek olması gerekmektedir. Erken yaş yüksek dayanımlı, boyutsal uyumluluk ve yüksek bağ performansı gösteren nano boyutta modifiye edilmiş YPLDÇK karışımlarının geliştirilmesi bu tezin temel amacıdır. Bu amaç doğrultusunda, %0, %55 ve %65 uçucu kül ve %1.5 nano silika, % 1,0 nano alümin ilave edilerek ayrı ayrı hazırlanan karışımlarla YPLDÇK karışımları üretilmiştir. YPLDÇK karışımlarında kullanılacak kimyasal katkı maddesinin oranının belirlenmesinde mini yayılma testi yapılmış olup sertleşmiş numunelerin temel mekanik özellikleri ise eğilmede çekme, basınç dayanımı ve elastisite modülü deneyleri ile belirlenmiştir. Modifiye edilmiş YPLDÇK' nin onarım malzemesi olarak kullanılabilirliği açısından çok önemli bir özellik olan bağ performansı eğik kesme mukavemeti test yöntemiyle saptanmış olup boyutsal stabilite özelliklerinin araştırılması için kısıtlanmış rötre deneyi, dayanıklılık performansı için ise hızlı klor iyonu geçirimliliği deneyi yapılmıştır. Son olarak, deneyler sonrası hazırlanan numuneler üzerinde matris ve lif-matris ara yüz özellikleri mikroyapısal analiz (SEM) yöntemi kullanılarak incelenmiştir. Sonuç olarak, nano malzemelerin yüksek hacimde uçucu kül içeren karışımlara ikame edilmesiyle harç numunelerinin mekanik ve mikro-yapısında iyileşmelerin olduğu görülmüştür. Ayrıca, karışımlarda kullanılan nano malzemeler, numunelerdeki boşluk miktarlarını azaltarak numunelerin daha geçirimsiz olmasını sağlamışlardır.Infrastructures are often found to be damaged or deteriorated under repetitive mechanical and environmental loads. The damaged structures which are repaired frequently cause big problems in terms of environment and economy. In recent years, it has been concluded that high performance fiber reinforced cementitious composites (HPFRCC) can be used successfully in repair and strengthening works. The use of high volume fly ash due to micromechanics-based design criteria in the production of HPFRCC has nearly become a requirement. To use of HPFRCC including high volume fly ash for especially important repair works of infrastructure (concrete road etc.) it should possess high strength for early age as well high dimensional stability. The main purpose of the thesis is that nanomodified HPFRCC mixtures will be produced to have high early age strength and durability, high dimensional stability and high connection performance between nanomodified HPFRCC mixtures and concrete that will be repaired. For this purpose, 0 %, 55 % and 65 % fly ash and 1.5 % nano silica, 1% nano alumina were added seperately to mixtures to produce HPFRCC. Flow table test for mortar was used to determine the ratio of chemical additives to be used in HPFRCC mixtures. The basic mechanical properties of hardened samples were determined by flexural, compressive strength and elasticity modulus tests. While bond performance of nanomodified HPFRCC, a feature that is very important for repair materials, were be determined by slant shear test, a restricted shrinkage test was conducted to investigate the dimensional stability properties of the hardened samples and a rapid chloride ion permeability test was performed for durability performance. Finally, the matrix and fiber-matrix interface properties of the samples prepared after the experiments were examined by using the microstructural analysis (SEM) method. As a result, improvements in the mechanical and microstructure of the mortar samples were observed by substituting nano materials to mixtures containing high volumes of fly ash. In addition, nano materials used in the mixtures reduced the amount of voids in the samples and allowed the samples to be more impermeable

Ultra-low density foam concrete production using electrolyzed water

With the development of foam concrete production technology, its usage area is increasing day by day. In this study, foam concrete was produced by using electrolyzed water to solve the problem of setting and low early-age strength, especially in low-density foam concrete production. According to obtained results, with the use of electrolyzed water technology in the production of foam concrete, the thermal conductivity coefficient decreased and the strength at early ages increased. Thus, foam concrete production will be made more rapidly. © 2021 by ASTM Internationa

Concrete Production with Using Magnetized Water

Dünyada ve özellikle gelişmiş ülkelerde beton, ekonomik olması, üretiminin kolaylığı, istenilenşeklin verilebilmesi ve özellikle dayanım ve durabilite gibi mühendislik üstünlükleri nedeniyleen çok tercih edilen yapı malzemesidir. Sürekli artan beton üretimi neticesinde bu alanda yapılanbilimsel araştırmalarda hızlı bir ivme kazanmıştır. Bu çalışmada, manyetize edilmiş su ile üretilenbeton ile normal karışım suyu ile üretilen geleneksel beton kıvam ve basınç dayanımı açısındankarşılaştırılmıştır. Manyetize edilmiş su kullanılarak üretilen betonların su ihtiyacı azalmış vesu/çimento oranı azalması neticesinde basınç dayanımı artış göstermiştir. Beton üretimindekullanılan karışım suyunun manyetize edilerek kullanılması ile prefabrik ve hazır betonüreticilerine yeni bir bakış açısı kazandırılarak daha ekonomik ve kaliteli beton üretim olanağısunulmuştur.In the world and especially in developed countries, concrete is the most preferred building material due to its economical efficiency, ease of production, giving the desired shape and especially its engineering advantages such as strength and durability. As a result of the constantly increasing concrete production, this field of scientific researches has gained a rapid acceleration. In this study, concrete sample produced with magnetized water is compared to conventional concrete produced with normal mixing in terms of consistency and compressive strength. The water requirement of concretes produced using magnetized water has decreased and the compressive strength has increased as a result of the decrease in water / cement ratio. With the use of the mixture water used in concrete production by magnetizing, prefabricated and readymixed concrete producers have been given a new perspective and provided more economical and quality concrete production opportunities

Çelik Liflerin Geometrik Şeklinin ve Oranının Beton Özelliklerine Etkisinin Araştırılması

Birçok araştırmada betonun teknik özelliklerini artırmak için farklı cins ve tiplerdeki liflerle çalışmalar yapılmıştır. Genellikle sonyıllarda betonun mekanik özeliklerinin öncelikli olan yerlerde çelik lif tercih edilmektedir. Bu çalışmada, tarafımızca şekil verilerekoluşturulan 2 farklı çelik lif tipi (Z, C şeklinde) ve 80/60 çelik lifi, çimento ağılığının 0.0, 0.10, 0.15 ve 0.20 oranlarındakullanılmıştır. Bu farklı şekillere sahip çelik liflerin, taze betonda oluşturdukları hava %’si miktarı ve işlenebilme özelliğigözlenirken; sertleşmiş betonda ise basınç, eğilme ve aşınma dayanımlarına olan etkileri incelenmiştir. Lifin şekli ve oranının, tazeve sertleşmiş beton özellikleri üzerinde etkili olduğu görülmüştür. Taze ve sertleşmiş betonda en optimum özellik, 80/60 lifinin%10 kullanılmasıyla elde edilmiştir.Many studies have been conducted with fibers of different types and shapes to increase the technical properties of concrete. Generally, steel fiber has been preferred in the places where the mechanical properties of concrete have priority in recent years. In this study, 2 different steel fiber types (Z, C shaped) and 80/60 steel fiber, which are formed by us, were used in the ratios of cement weights at 0.0, 0.10, 0.15 and 0.20. While the amount of air content and the workability of the steel fibers of these different shapes added in fresh concrete were observed; In hardened concrete, its effects on compressive strength, flexural strength and abrasion resistance were investigated. The shape and ratio of the fiber have been shown to be effective on fresh and hardened concrete properties. The optimum feature in fresh and hardened concrete has been achieved by using 10% of 80/60 fiber

Effect of Supplementary Cementitious Materials with Similar Specific Surface Area on Cementitious Composite Systems

This study investigated the effect of the mechanical and durability properties of cementitious composite systems with supplementary cementitious materials (SCMs), including fly ash (FA), ground granulated blast furnace slag (GGBS), and bottom ash (BA), with similar specific surface areas (similar to 3,300 cm2/g). FA, GGBS, and BA were ground to a specific surface area of similar to 3,300 cm2/g (about the cement-specific surface area) and then replaced with cement at 5 %, 10 %, 15 %, and 20 % replacement ratios. The compressive strength, flexural strength, length change, and rapid chloride ion permeability of the cementitious composites incorporating FA, GGBS, and BA with similar specific surface areas were recorded after 7-, 28-, and 90-day curing periods. As a result, cementitious composites containing GGBS improved the mechanical and durability properties at the maximum rate. It was shown that the properties of cementitious composites containing 20 % GGBS yielded better results than the control specimens without any SCMs

The impact of RCA and fly ash on the mechanical and durability properties of polypropylene fibre-reinforced concrete exposed to freeze-thaw cycles and MgSO4 with ANN modeling

An experimental study has been conducted to investigate the impact of recycled coarse aggregate (RCA) and fly ash (FA) on the transport, mechanical and durability properties of polypropylene fiber reinforced concretes. In this context, nine concrete mixtures with 25% FA as cement replacement (by wt.) and nine mixtures without FA were produced. RCA was used to replace natural coarse aggregates (NCA) at 0, 25 and 50% by wt. in all concrete mixtures. In addition, polypropylene fiber (PPF) was added to concrete mixtures at 0, 3 and 6% by volume. Mechanical performance was evaluated by compressive, splitting tensile strength at 7, 28 and 90 days and Schmidt rebound hammer at 90 days. Dry bulk density, water absorption, apparent porosity and sorptivity of concrete were also evaluated. Durability performance of concretes was evaluated by exposing to 50,100 and 150 freeze-thaw cycles and MgSO4 attack. Abrasion test on the concretes was also performed. After performing durability tests, compressive, splitting tensile strength, ultrasonic pulse velocity, microstructural observations and mass loss of the concretes were assessed. An artificial neural network (ANN) was also modeled for predicting experimental data. The results indicated that combined use of RCA, FA and PPF improved the compressive strength considerably and approximately 60 MPa was obtained in concretes with 25 and 50% RCA. The use of RCA in concretes with 25% FA has improved the mechanical properties. The mixture with 25% RCA, 6%PPF and without FA and the mixture with 50% RCA, 3%PPF and FA showed the best abrasion resistance. Reference and the mixture with 0% RCA, 25% FA and 6% PPF exhibited the lowest strength loss after the MgSO4 attack. Reference and the mixture with 25% RCA, 25% FA and 3% PPF performed the best after 100F-T cycles in terms of compressive strength. With the Bayesian regularized algorithm, material quantities for the target concrete properties can be obtained. The main outcome of this study is that using RCA, FA and PPF in concrete can give better performance in terms of mechanical and durability performance than normal concrete. © 2021 Elsevier Lt