Polimer katkılı çimento betonları

Abstract

Polimer çimento betonları, normal çimento betonuna karışım sırasında polimerin belirli oranlarda (polimer-çimento oranı, ağırlık olarak, % 5-% 20) katılmasıyla elde edilen yapı malzemeleridir, içine katılan polimer katkı maddelerinin üstün özellikleri nedeniyle, normal çimento betonuna göre oldukça iyi performansa sahiptirler. Gelişmiş ülkelerde yaygın kullanım alanları vardır. Bu tezde, polimer çimento betonlarının işlem teknolojisi, özellikleri belirtilerek, değişik oranlarda (polimer-çimento oranı %5-% 15) ve farklı tiplerde (PVA, akrilonitril, akrilik) polimer ilavesiyle oluşan betonların nitelikleri deneylerde ele alınmıştır. Deneyler sonucunda polimer çimento betonlarının -normal betona göre- oldukça iyi fiziksel ve mekanik özelliklere sahip oldukları belirlenmiştir.

Concrete is one of the most important building materials of our century and is being used widely in the field of civil engineering. Therefore, some investiga tions and studies are being carried out throughout the world for the purpose of developing the characteristics of the concrete and also of adding some new characteristics to it. The developments assured by technology have found their reflection on the construction world and due to the attempts ai ming at producing high-quality and durable concretes, some additives have been used inside the concrete. One of these additives is polymer (plastic) used presently in the field of civil engineering and some other fields. This is called as concrete-polymer composites as well because its addition into concrete is at the higher rate than other additives. The purpose in adding the polymers into concrete is to develop some characteristics of concrete such as impermeability, abrasion, frost-resistance etc. and also to increase the du rability thereof. The use of polymers in concrete technology became important in 1950's. In the previous years, bitumen, natural rubber latex was being added to concre te, but the utilization of artificial polymers was recorded later. From the 1965 onwards, some attractive developments were observed in this field. The in vestigations in this field are still continuing with increased interest. The field of use of polymer cement concrete (polymer Portland cement conc rete or polymer modified concrete) which is discussed in this thesis and is a kind of concretes with polymer (concrete-polymer composites) is very wide since their production methods is similar to those of ordinary cement concre te with no additive. Polymers are added at the rate of 5 % - 20 % of the ce ment weight to ordinary cement concretes during mixing. Because of - v - superior properties of polymers, polymer cement concretes have good per formance in comparison with conventional cement concretes. They are wide ly used in developed countries. The characteristics of the concrete are sub ject to the characteristics of additives (cement, sand, aggregates), the type of polymers and the curing conditions. This study focuses, by defining the concrete, concrete additives and poly mers at first, on the production methods and characteristics of the polymer cement concretes which is a kind of the concretes with polymer. Furthermo re, it contains some experimental studies in which the characteristics formed due to the different-type and various-rate plastics to such concretes are com pared with to those of normal concrete. The process technology and properti es of polymer cement concretes have been explained and the features of those with different amounts (polymer-cement ratio 5-15%) and types (PVA, acrylonitrile, acrylic) of polymer have been examined at the result of experi ments. Consequently, it is determined that they have improved physical and mechanics properties compared to those of ordinary cement concretes. This study consists of seven chapters. In the first chapter, the aim of the study has been introduced with its covera ge. In the second chapter, it has given general informations about kinds of conc rete and their compressive strenghts. In the third chapter, concrete additives have been taken into consideration in means of the effects on properties of concrete of these. In the fourth chapter, plastics (polymers), polymerization, kinds of polymer, properties of polymers have been explained and some polymers (polyvinyia- setat, polyacrylonitril) which are added to concrete in the experimental studi es have been introduced. In the fifth chapter, concrete-polymer composites are the relatively new - vi - construction materials which are made by improving the properties of con ventional cement concrete with polymeric materials, have been classified into three types and it has been dealed with the recent research and deve lopment in the concrete-polymer composites in the world. The sixth chapter contains principles of polymer modification, process tech nology and properties of polymer cement concrete (polymer portland cement concrete or polymer modified concrete) which is discussed in this thesis. The seventh chapter consists of mechanical and physical experiments to ob tain the necessary data. The results of flection, pressure, water absorbtion, ultrasonic, frost-resistance, specific weight-experiments and conclusions drawn out of this study have been also given in this chapter. Concrete-polymer composites are the materials which are made by replacing a part or all of the cement hydrate binder of conventional mortar or concrete with polymers, and by strengthening the cement hydrate binder with the poly mers. For the past 40 years, the active research and development of concre te-polymer composites have been conducted all over the world, particularly in the United States, the Soviet Union, the United Kingdom, Japan and Ger many. However, it seems that the history of the research and development is considerably different in various countries because of a difference in the background. At present, the concrete-polymer composites are drawing much attention as high-performance or multifunctional materials in the construction industry as well as the mechanical, electrical and chemical industries. The concrete-polymer composites are generally classified into the following three types by the principles of their process technology : 1. Polymer-modified (or cement) mortar (PCM) and concrete (PCC) 2. Polymer mortar (PM) and concrete (PC) 3. Polymer-impregnated mortar (PIM) and concrete (PIC) Polymer-modified mortar and concrete were developed in the 1920's to - VII 1930's, polymer mortar and concrete in the 1950's, and polymer- impregnated mortar and concrete in the 1 960's. Considerable research and development of these three types of concrete-polymer composites were competitively conducted in the 1970's. In the 1980's, the polymer-modified mortar and concrete, and polymer mortar and concrete became the domi nant materials. At present, the polymer-modified mortar and concrete, and polymer mortar and concrete are used as popular construction materials. By contrast, the polymer-impregnated mortar and concrete are hardly employed because of a poor balance between their performance and cost due to their high processing cost and awkwardness in applying the process, though they have excellent performance. Recently, a strong interest has been shown to ward the applications of the concrete-polymer composites to the repair and restoration of damaged reinforced concrete structures. To produce polymer-modified mortar and concrete, mostly polymers in dis persion (latex or emulsion) form are added to ordinary cement mortar and concrete during mixing. The polymer-modified mortar and concrete have considerable attraction since their process technology is very similar to that of the ordinary cement mortar and concrete. The polymer-modified mortar and concrete are usually moist-cured for a few days, and then air-cured under their service conditions. Most polymer- modified mortar is troweled in the field. The polymer-modified concrete is pla ced in the same manner as ordinary cement concrete. Because the rapid deterioration of reinforced concrete structures has beco me a serious problem, a strong interest is focused on the polymer-modified mortar and paste as repair materials, and there is a growing demand for them. Consequently, the polymer-modified mortar and concrete can be re commended as low-cost, promising materials for preventing chloride-induced corrosion and repairing damaged reinforced concrete structures. In their practical applications, the potential importance of property mismatch betwe en repair materials and the reinforced concrete substrates has been highligh ted. Polymer-modified mortar is most widely used as a construction material for - VIII - finishing and repairing works. However polymer-modified concrete is widely used for bridge deck overlays and patching work. Various water-soluble poly mers such as methyl cellulose (MC), hydroxyethyl cellulose (HEC), polyvinyl alcohol (PVAc) and polyacrylate are used as admixtures for plastering work or underwater concreting work. Consequently, polymer cement concrete is a popular construction material in the world (specially in the developed countries) and the field of use is develo ped day by day.