Effect of Freeze-Thaw Cycles on Mechanical Properties of Jute Fiber Reinforced Concrete for Pavement

Abstract

Concrete is usually used as a construction material in many infrastructures; because of its performance and behaviour. Freeze-thaw is one of the major hazards for pavements; which they have to experience due to fluctuation in seasonal temperatures. Certain measures should be made to save the concrete pavements from the freeze-thaw deterioration at the time of construction. The behaviour of concrete during freeze-thaw can also be improved if the crack initiation is controlled. The use of fibers in concrete to improve its properties is very ancient. Fibers are used to enhance the properties of concrete like mechanical, absorption and crack control properties etc. Natural fibers have many advantages due to low cost, ease of availability and less hazard for health. Experiments are conducted for three different cycles (10, 20 and 30) of freeze-thaw. Single combination of mix design, water cement ratio, fiber type, fiber length and content are considered. The overall aim of this study is to examine the behaviour of dynamic and mechanical properties of plain concrete (PC) and jute fiber reinforced concrete (JFRC) after subjecting to freeze-thaw cycles. The mix design ratio, which is used for preparation of PC is 1:2:3:0.6 (cement: sand: aggregate: water). Jute fibers are added in similar mix design ratio with a ratio of 5% by mass of cement for preparation of JFRC. Mechanical and dynamic properties of PC and JFRC specimens are measured by using ASTM standards. Procedure B is used as per ASTM standard C666/C666M-15, in which rapid freezing in air and thawing in water for freezethaw process. One cycle of freeze-thaw is completed by lowering the temperature from 4 to -18oC and raising it back from -18 to 4oC, in time not less than 2 hours and not more than 5 hours. After curing of specimens for 28 days before the start of freeze-thaw process, mass and dynamic properties are measured. After completion of freeze-thaw cycles mass of each specimen and dynamic properties are measured to check the effect of freeze-thaw process on PC and JFRC specimens. Empirical equations are developed and practical example is calculated by using experimental results of JFRC and PC. ix Workability of JFRC is less than PC with same mix design and w/c ratio, due to which slump of JFRC is less than PC. JFRC specimens have low weight than PC specimens. Due to less weight densities of JFRC specimens are less than PC specimens. Percentage of loss in mass due to different freeze-thaw cycles is more in JFRC specimens as compared to PC specimens. Relative dynamic modulus of elasticity (Pc) of JFRC specimens is decreasing very slowly as compared to PC specimens which indicate JFRC specimens can bear more freeze-thaw cycles. Split tensile and flexural strengths of JFRC are increased up to 11% and 2% whereas, 16% decreased in compressive strength of JFRC specimens is observed as compared to PC specimens. Strengths of PC and JFRC are decreasing as number of freeze-thaw cycles are increased. Empirical equations are developed by using numbers of freeze-thaw cycles, loss in mass, compressive strength, flexural strength and compared with experimental results. Design thickness of rigid pavement is measured with help of obtained experimental results modulus of rapture (MoR), compressive strength and modulus of elasticity. The thickness of rigid pavement is reduced by using jute fibers in concrete as compared to normal concrete. An increase of 28% in pavement thickness is required by using normal concrete to resist the effect of 30 cycles of freeze-thaw. However, by using jute fibers, only 19% increase in thickness is required.