Reducing Concrete Drying Shrinkage Using Superabsorbent Cellulose Fiber

The presence of shrinkage cracks in concrete is one of the major issues affecting concrete durability. Loss of moisture, changes in temperature, and hydration process are few reasons that cause shrinkage cracks in concrete. Among all types of shrinkage, drying shrinkage contributes a major portion of shrinkage strain in conventional concrete. Various parameters that affect the drying shrinkage of concrete are the element thickness, porosity, paste volume, fineness of the binder, water-cement ratio, fiber content, temperature, and relative humidity. The objective of this study is to develop a pulp fiber-based concrete mix that is capable of reducing concrete drying shrinkage. This study aims at developing a concrete mix that is acceptable for both its fresh and hardened properties with low drying shrinkage and cracking. To achieve this objective, Superabsorbent Cellulose Fibers (SCF) derived from water-insoluble, lignin-free Softwood Kraft Pulp fibers is used in concrete mix as a percentage of the total weight of water and cement content. Concrete mix design is performed for a target compressive strength of 35 MPa for exposure class C-1. Mix proportions are systematically designed to capture all the variables that affect the fresh and hardened concrete properties. The microstructure of hardened SCF concrete is studied using Scanning Electron Microscope (SEM) images. Test results for both fresh and hardened concretes are analyzed prudently to define the optimum SCF content. It is expected that the outcome of this study will aid in reducing the drying shrinkage in concrete.