Elektro-osmozun katkılı ve katkısız portland çimento harçlarına etkisi
Elektro-osmozun katkılı ve katkısız portland çimento harçlarına etkisi
Dosyalar
Tarih
1985
Yazarlar
Türker, Fikret
Süreli Yayın başlığı
Süreli Yayın ISSN
Cilt Başlığı
Yayınevi
Fen Bilimleri Enstitüsü
Institute of Science and Technology
Institute of Science and Technology
Özet
jğurma suyu miktarı (veya su/çimento oranı), beton teliklerine etki eden en önemli faktörlerden biridir. Beton üretimi sırasında taze betona katılan su miktarı, çimentonun hidratasyonu için gerekli olan miktarın çok üzerindedir.Fazla su, taze karışıma yeterli işlenebilirlik vermek için katılır. Öte yandan azla su, sertleşmiş beton özeliklerini olumsuz yönde etkiler. Taze betona katılan fazla suyu geri almak amacıyla elektro-osmotik drenaj yönteminden yararlanılabilir. Ancak, elektro-osmotik drenaj yöntemi yaygın olarak kullanılmamaktadır.Bu çalışmada, elektro- osmotik yöntemin taze harç karışımlarında fazla suyu geri almak amacıyla kullanılabilirliği ve işle- min sertleşmiş harç özelikleri üzerindeki etkileri araştırılmıştır.Bu konuda bilimsel nitelikte çalışmaya rastlanılamamış olması nedeni ile, temel nitelikte bir çalışma yapılması amaçlanmıştır.Bu nedenle yöntemin pratikte uygulanması ile ilgili sorunlar üzerinde durulmamış ve deneysel çalışmalar beton yerine harç karışımları ile gerçekleştirilmiştir. Çalışma 6 bölüm içermektedir. 1 inci bölümde, su/ çimento oranının beton özelikleri üzerindeki etkilerine kısaca değinilerek, araştırmanın amacı ve II kapsamı belirtilmiştir. 2 inci bölümde, çeşitli kaynaklardan elde edilen, konu ile ilgili bilgiler verilmiştir.Bu bölüm, taze çimento hamuru, harç ve betondaki fiziksel, kimyasal ve fizikokimyasal değişimleri, çimento elektor-kinetiği, elektro-osmozun mekanizması ve inşaat mühendisliğindeki uygulamalarına ait bilgileri içermektedir. 3 üncü bölümde, deneysel çalışmada kullanılan malzemelerle ilgili özelikler, drenaj yöntemi ve üretilen harç karışımları ile ilgili bilgiler verilmiştir. Deneyler katkısız, Ca(OH)p katkılı ve kal- yum linyosulfonat katkılı harç karışımları üzerinde yapılmıştır.Deneyler sırasında taze harçta katı yüzeyin oturması, harcın çeşitli yüksekliklerindeki elektriksel dirençler, drenaj deneylerinde drene edilen su miktarı, zamana bağlı olarak ölçülmüştür. İşlemlerin sertleşmiş harç özelikleri üzerindeki etkilerini anlayabilmek için sertleşmiş harçta birim ağırlık, kılcallık katsayısı, ultra-ses hızı, basınç dayanımı gibi özelikler saptanmıştır. 4 üncü bölümde taze harçlardaki ölçüm sonuçları değerlendirilmiştir.Taze harçta su drenaj hızları, katı yüzeyin oturma hızı ve kapasitesi, elektrik sel dirençlerin zamanla değişimi incelenerek, elek- Ill tro-osmotik su hareketinin gelişimi ile ilgili sonuçlar çıkarılmağa çalışılmıştır. 5 inci bölümde sertleşmiş harç özelikleri irdelenmiştir.Drenaj işlemine bağlı olarak taze harçta meydana gelen boşluk yapısı değişimi ve elektro- kimyasal olaylarla sertleşmiş harç özelikleri arasındaki ilişkiler ortaya konulmuştur. 6 ncı bölümde, çalışmada elde edilen sonuçlar top lu olarak verilmiştir.Çalışma sonuçlarına göre,elektro-osmotik işlemle sertleşmiş harç özeliklerin de önemli ölçüde olumlu değişmeler sağlanabilir.Bu olumlu değişmelerin en Önemli nedeni, su drenajı sonucu taze harçta kılcal boşluk miktarının azalmasıdır. Bu olay, harcın basınç dayanımını artırıcı ve kılcal su emmesini azaltıcı etki yapmaktadır. Olumlu etkilerin diğer nedeni, uygulanan voltaja bağlı olarak taze harçta meydana gelen elektro- kimyasal değişmelerdir.Elektro-kimyasal değişmelerin olumlu etkilerini, kalsiyum esaslı katkı mad deleri kullanarak artırmak olanağı vardır. Çalışma elektro-osmotik işlemin, sertleşmiş harç ve beton özeliklerini iyileştirmek amacıyla kullanılabileceğini göstermektedir.Ancak yöntemin pratikte kullanılabilmesi için daha çok araştırma yap mağa gerek vardır.
Water/cement ratio is one of the important factors affecting hardened concrete properties.In concrete production, water amount added to fresh mixture is much more than necessary for cemet hydration. Excess water evaporates and leaves voids in concrete struc ture. These voids affect reversly hardened concrete properties (compression strength, capillarty, etc.) On the other hand, excess water is necessary for fresh mixture to have a good workability. To produce concrete with good workability but low water/cement ratio, water-reducing admixtures can be added to fresh mixture as well as excess water can be drawn back by vacuum technic, after concrete with high water/cement ratio was placed in mould. One of the technics used to draw back excess water from fresh concrete is electro-osmotic drainage. Electro-osmotic technic is used for dewatering clayey soils »During application of this technic, soils can be stabilized electro-chemically.Simi larly, electro-osmotic technic has been used in the concrete for the same purpose, but the application was very restricted. In this study, applicability of electro-osmotic V drainage to draw back excess water from fresh mor tar mixture and affects of its application on the hardened mortar properties have been researched. Because not many satisfactory scientific papers could have been found on this subject, this study has been undertaken as a basic study. For this pur pose, problems of application of the electro-osmo tic drainage in concrete practice has not been considered and thus experimental study has been made on mortar mixtures in place of concrete during the work.Concrete properties are closely related to mortar phase properties.So with the results of this study, it will become easy to make further studies on concrete. The study contains six chapters. In the first chap ter, affects of water/cement ratio on hardened concrete properties have been reviewed and the aim and scope of the study has been presented. In the second chapter, knowledges gathered from different sources on the subject have been given, these knowledges contain physical, chemical and physico-chemical aspects of the function of water in fresh cement paste, mortar and concrete. The water and solid grain movement in fresh mixtures have been included.Then knowledges on cement elec tro-kinetics, mechanism of electro-osmosis and VI and civil engineering application of electro- osmosis have been given. In the third chapter, properties of materials used in the experimental studies, experimental technics and properties of mortar mixtures produced in the laboratory have been given, As mentioned in this chapter, experimental studies have been performed on mortar with and without admixture.Calcium based admixtures have been used because of their affects on the electro-kinetic properties and hydration of cement. One of these admixtures is pure Ca(OH)^ and the other is calcium lignosulphonate based water- reducing admixture. For all but one group of mortar mixtures, workabi lity is constant.Water amount was reduced in mor tars with calcium lignosulphonate based admixture in order to have the same workability as in the non-admixture mortar mixtures. For a group of mortar mixture containing this admixture, water/cement ratio was kept constant and thus workability could be increased. During the experiments, settlement of solid surface of mortar, electrical resistance of mortar along horizontal direction at various heights and water drawn back for drainage applications were measured VII in order to follow variations in fresh mixtures, jensity, capillarity constant, ultra-sound velocity and compression strength of hardened mortar specimens was ascertained to understand the affects of the technic on the hardened mortar properties. Tn the fourth chapter, experimental results ob*- tained from fresh mixtures have been discussed. Conclusions have been drawn by examined drainage velocity, settlement velocity, settlement capacity, variations of electrical resistance in fresh mor tar with time in relation to affects of admixture and the affects of the application way of electro- osmosis and applicated voltage. So it could be pos sible to have better understanding öf the electro- osmotic water movement in fresh mortar mixtures. In the fifth chapter, variations on the hardened mortar properties and causes of these variations in relation with the drainage application and electro-chemical affects have been examined. In this chapter, relations between variations of void struc ture after drainage in the fresh mortar mixtures and variations of hardened mortar properties have been examined in the view of the experimental re sults.Attempt was made to find a relation between the variation of the compression strength and the variation of void content and void structure. For VIII this attempt, results of density, capillarity cons tant and ultra-sound velocity measurements which reflected void structure of hardened mortar have been used. This chapter also includes, electro-chemical vari ations in the fresh mixtures due to D.C. voltage and affects of these variations on the hardened mortar properties.Since we haven't any measurement other than electrical resistance of fresh mixtures reflecting electro-chemical variations and their affects, this examination was based on the inves tigations of electro-chemical stabilization in soils. Some analogies have been made between soils and mortar mixtures. In the sixth chapter, conclu sions drawn from investigation have been summari zed. It can be concluded that important improvements of the hardened mortar properties by electro-osmo tic application are possible.Most important causes of these improvements are variations of void struc ture and void amount in relation with water draina ge.As a result of water drainage, amount of capil lary voids in fresh mortar is reduced.Since capil lary voids have a decreasing affect on the com pression strength, less capillary voids make har dened mortar to have more strength. On the other hand, less capillary voids cause less capillary water suction in the hardened mortar. It is clear IX that these improvements will result in a more durable mortar. Property improvements on the hardened mortar are not only related to water amount drawn back from fresh mixture, but also on some electro-chemical variations resulting from the voltage application. It can be shown that, more affirmative improvements of electro-chemical variations on the hardened mortar properties are possible especially with admixtures containing calcium ions. This study demonstrates that, electro-osmotic tech- nic can be used to improve hardened mortar and concrete properties, but it is necessary to inves tigate the subject further in order to apply the technic to concrete specially in reinfoced struc ture.
Water/cement ratio is one of the important factors affecting hardened concrete properties.In concrete production, water amount added to fresh mixture is much more than necessary for cemet hydration. Excess water evaporates and leaves voids in concrete struc ture. These voids affect reversly hardened concrete properties (compression strength, capillarty, etc.) On the other hand, excess water is necessary for fresh mixture to have a good workability. To produce concrete with good workability but low water/cement ratio, water-reducing admixtures can be added to fresh mixture as well as excess water can be drawn back by vacuum technic, after concrete with high water/cement ratio was placed in mould. One of the technics used to draw back excess water from fresh concrete is electro-osmotic drainage. Electro-osmotic technic is used for dewatering clayey soils »During application of this technic, soils can be stabilized electro-chemically.Simi larly, electro-osmotic technic has been used in the concrete for the same purpose, but the application was very restricted. In this study, applicability of electro-osmotic V drainage to draw back excess water from fresh mor tar mixture and affects of its application on the hardened mortar properties have been researched. Because not many satisfactory scientific papers could have been found on this subject, this study has been undertaken as a basic study. For this pur pose, problems of application of the electro-osmo tic drainage in concrete practice has not been considered and thus experimental study has been made on mortar mixtures in place of concrete during the work.Concrete properties are closely related to mortar phase properties.So with the results of this study, it will become easy to make further studies on concrete. The study contains six chapters. In the first chap ter, affects of water/cement ratio on hardened concrete properties have been reviewed and the aim and scope of the study has been presented. In the second chapter, knowledges gathered from different sources on the subject have been given, these knowledges contain physical, chemical and physico-chemical aspects of the function of water in fresh cement paste, mortar and concrete. The water and solid grain movement in fresh mixtures have been included.Then knowledges on cement elec tro-kinetics, mechanism of electro-osmosis and VI and civil engineering application of electro- osmosis have been given. In the third chapter, properties of materials used in the experimental studies, experimental technics and properties of mortar mixtures produced in the laboratory have been given, As mentioned in this chapter, experimental studies have been performed on mortar with and without admixture.Calcium based admixtures have been used because of their affects on the electro-kinetic properties and hydration of cement. One of these admixtures is pure Ca(OH)^ and the other is calcium lignosulphonate based water- reducing admixture. For all but one group of mortar mixtures, workabi lity is constant.Water amount was reduced in mor tars with calcium lignosulphonate based admixture in order to have the same workability as in the non-admixture mortar mixtures. For a group of mortar mixture containing this admixture, water/cement ratio was kept constant and thus workability could be increased. During the experiments, settlement of solid surface of mortar, electrical resistance of mortar along horizontal direction at various heights and water drawn back for drainage applications were measured VII in order to follow variations in fresh mixtures, jensity, capillarity constant, ultra-sound velocity and compression strength of hardened mortar specimens was ascertained to understand the affects of the technic on the hardened mortar properties. Tn the fourth chapter, experimental results ob*- tained from fresh mixtures have been discussed. Conclusions have been drawn by examined drainage velocity, settlement velocity, settlement capacity, variations of electrical resistance in fresh mor tar with time in relation to affects of admixture and the affects of the application way of electro- osmosis and applicated voltage. So it could be pos sible to have better understanding öf the electro- osmotic water movement in fresh mortar mixtures. In the fifth chapter, variations on the hardened mortar properties and causes of these variations in relation with the drainage application and electro-chemical affects have been examined. In this chapter, relations between variations of void struc ture after drainage in the fresh mortar mixtures and variations of hardened mortar properties have been examined in the view of the experimental re sults.Attempt was made to find a relation between the variation of the compression strength and the variation of void content and void structure. For VIII this attempt, results of density, capillarity cons tant and ultra-sound velocity measurements which reflected void structure of hardened mortar have been used. This chapter also includes, electro-chemical vari ations in the fresh mixtures due to D.C. voltage and affects of these variations on the hardened mortar properties.Since we haven't any measurement other than electrical resistance of fresh mixtures reflecting electro-chemical variations and their affects, this examination was based on the inves tigations of electro-chemical stabilization in soils. Some analogies have been made between soils and mortar mixtures. In the sixth chapter, conclu sions drawn from investigation have been summari zed. It can be concluded that important improvements of the hardened mortar properties by electro-osmo tic application are possible.Most important causes of these improvements are variations of void struc ture and void amount in relation with water draina ge.As a result of water drainage, amount of capil lary voids in fresh mortar is reduced.Since capil lary voids have a decreasing affect on the com pression strength, less capillary voids make har dened mortar to have more strength. On the other hand, less capillary voids cause less capillary water suction in the hardened mortar. It is clear IX that these improvements will result in a more durable mortar. Property improvements on the hardened mortar are not only related to water amount drawn back from fresh mixture, but also on some electro-chemical variations resulting from the voltage application. It can be shown that, more affirmative improvements of electro-chemical variations on the hardened mortar properties are possible especially with admixtures containing calcium ions. This study demonstrates that, electro-osmotic tech- nic can be used to improve hardened mortar and concrete properties, but it is necessary to inves tigate the subject further in order to apply the technic to concrete specially in reinfoced struc ture.
Açıklama
Tez (Doktora) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 1985
Thesis (Ph.D.) -- İstanbul Technical University, Institute of Science and Technology, 1985
Thesis (Ph.D.) -- İstanbul Technical University, Institute of Science and Technology, 1985
Anahtar kelimeler
İnşaat Mühendisliği ,
Civil Engineering