Title:
High-Early-Strength-Concrete: Mix Proportioning with Processed Cellulose Fibers for Durability
Author(s):
Parviz Soroushian and Siavosh Ravanbakhsh
Publication:
Materials Journal
Volume:
96
Issue:
5
Appears on pages(s):
593-600
Keywords:
cellulose fibers; cement content; durability; mixture proportioning
DOI:
10.14359/662
Date:
9/1/1999
Abstract:
The growth in fast-track construction and repair has prompted major efforts to develop high-early-strength concrete mix compositions. Such mixes rely on the use of relatively high cement and accelerator contents to increase the rate of strength development. These measures, however, seem to compromise the long-term performance of concrete in applications such as full-depth pavement patches. The hypothesis successfully validated in this research was that conventional methods of increasing the early-age strength of concrete, involving the use of high cement and accelerator contents, increase the moisture and temperature movements (i.e., shrinkage) of concrete. Restraint of such movements in actual field conditions, by external or internal effects, generates tensile stresses that introduce microcracks, and thus increase the permeability of concrete and accelerate various processes of concrete deterioration, including freeze-thaw attack. Fiber reinforcement of concrete is an effective approach to the control of microcrack and crack development under tensile stresses. Fibers, however, have not been known for accelerating strength development in concrete. The recently developed processed cellulose fibers were found to increase the early-age strength of concrete. This provides a unique opportunity to increase the rate of strength gain in concrete without increasing moisture and temperature movements, while actually controlling the processes of microcracking and cracking in concrete. Laboratory and preliminary outdoor test results confirmed the desirable resistance of processed cellulose fiber reinforced high-early-strength concrete to restrained shrinkage cracking, and thus to different processes of deterioration under weathering effects. A field project involving fast-track full-depth patching with processed cellulose fiber reinforcement was implemented in Michigan.