Cement based Repair Material Reinforced at Nano Scale

Abstract

Construction industry is at peak in industrial growth of developed and developing countries. Majorly used construction materials are cement based materials like mortar, concrete and repair material. To make structure sustainable and durable, mechanical, physical and durability properties play predominant role. Compressive strength of cement based material is outstanding as compared to it's tensile strength is the proven fact. Therefore, concept of implanting Carbon Fibers increase tensile strength, durability properties and reduce shrinkage cracks in case of the mortar and concrete. There has been growing interest in the past decades in Carbon Fibers(CFs) because of their remarkable mechanical and physical properties for various composite applications. At 1/6th the specifc gravity of steel, theoretical strength of CFs is 100times. Ultimate strength value of CFs is as high as 60GPa. CFs implanted cement composites develop nonstructural functions by taking advantage of structural material itself. Nonstructural functional properties includes strain/stress sensor, dynamic monitoring, temperature sensor, damage detection, anode for electrochemical chloride extraction, heating thermal control, electromagnetic wave shielding and many more. Comparative studies on dispersion of two Carbon Fiber (CF) types using surfactants like water, acetone, Glenium 3030 7101 and methyl-cellulose have been conducted. Sonication probe, magnetic stirrer and high shear homogenizer has been used and shown to dramatically increase the dispersion efficiency of CFs. After selecting the most reliable and practical dispersion method, mechanical behavior of CFs reinforced mortars has been also investigated with dosage at 2, 2.25 and 2.5 wt% of cement. Dog bone shape specimens were tested in early age under direct tension in order to evaluate the mechanical properties such as ultimate load, deflection and load - deflection behavior of CFs reinforced composites. On the other hand, the cubes were also prepared to determine the compressive strength of these composites. These results have been compared with each other as well as with the result of plain/control cement mortar specimen. Trend of results show increase in tensile strength with increase in dosage of the CFs. However, experimental results show the uncertainty in increase of tensile strength while increase in dosage of CFs. So, other trials have been made by dosage of CFs 1, 2 and 3% by volume of total mortar. Results of the new trial show similarity with the trend of results. Tensile strength of mortar is increased with increase in the CFs content. Flexural test has been also conducted on mortar beam samples. To investigate dispersion of CFs microscopic analysis was carried out. Results shows clotting and dispersed CFs side by side. So there is a need of use of different surfactant or change in dosage or technique improvement for getting better dispersion of CFs. Another experiment was carried out by using concrete. Primary objective was to produce high strength as well as durable concrete for Freeze and thaw effect. For most of the building material and components durability is an essential issue. In case of structural components exposed to freeze and thaw effect it becomes more important to protect them from the said effect. To improve resistance against freeze and thaw effect, air entertainment is universally used for concrete. Fiber reinforced concrete is widely used in the Bridge deck overlays and pavements. Such structures are exposed to freezing and thawing for the most part of the year, in majority of the locations of North America and Europe. Water and air content plays major role for the freeze and thaw effect. Results from different researches on fiber reinforced concrete show, under freeze and thaw cycling, behavior of the ber reinforced concrete is similar to plain concrete. Only the addition of entrained air content improves freeze and thaw durability. The durability of the ber reinforced concrete is similar to plain concrete for the same air content. CFs reinforced concrete, which is used for experimental work is exposed to 90cycles and no damage is obtained till present time duration of the test.