Fracture of glass fiber reinforced cement

Fracture patterns produced when a crack advancing from a notch in cement paste intersected a Cem FIL-2 glass fiber strand placed perpendicular to it were studied. The specimens were small notched compact tension specimens that could be wedge loaded in the scanning electron microscope chamber using a wet cell. Four distinct cracking patterns were identified. In most cases the fiber caused a shift in the crack path and in some specimens, microcracking and separation of the crack into 2 to 4 branches were observed. The filaments maintained their continuity and bridged over the track. Similar tests with E-glass fibers after accelerated curing revealed brittle behavior in which the crack path was straight and many filaments were broken.