Evaluation the effect of micro-synthetic fiber on mechanical and freeze-thaw behavior of non-air-entrained roller compacted concrete pavement using response surface methodology

Abstract

Freeze thaw durability of roller compacted concrete pavement (RCCP) is the main concern that may cause difficulties for its construction. In this paper the combination of both the cement content and water-to-cement (W/C) ratio parameters as cement-to-saturated surface dry aggregate ratio (C/A) and its effect on mechanical and durability properties of fiber reinforced RCCPs was investigated in laboratory scale by keeping water content (130 kg/m3), whereas, the specimens were compacted by vibrating hammer method. Moreover, the effect of short length micro-synthetic fiber on freeze thaw durability of RCCP specimens was evaluated and compared with control mixtures. A total of 16 RCCP mixtures with combination of various W/C ratios (0.35, 0.4, 0.45 and 0.5) and various cement content values (260–370 kg/m3) as C/A (13, 15, 17 and 19%) and various fiber volume fractions (Vf) (0 for control, 0.1, 0.3, 0.5%) were constructed in order to evaluate the effects on both fresh and hardened properties. The interactions of C/A and Vf were examined on responses including the Vebe time, dry unit weight (γd), compressive strength (fc-28), splitting tensile strength (ft-28), third point flexural strength (ff-28), ultrasonic pulse velocity (UPV), water absorption (WA), durability factor (Df) and weight loss at 300 freeze–thaw cycles (WL-300) using response surface methodology (RSM). The optimization was performed on all statistical regression models by maximizing ft-28 , Df and ff-28 and minimizing WA and WL-300 showed that C/A = 17.65% and fiberVf = 0.15% provided an optimum mixture leading the best mechanical and durability properties with the desirability of 0.994. It was found that the uniform distribution of the optimum fiber Vf through the concrete matrix with no mass collection can highly improve the mechanical and durability properties of RCCP. Furthermore, the WL-300 less than 5% represented an acceptable and more conservative limit than Df for identifying durable specimens.