On September 30, 1994, the space shuttle Endeavour roared off the launch pad carrying the world's first portland-cement-based- mortar experiment into space. The results of this important experiment, conducted by researchers at Master Builders Inc., Cleveland, and students from the University of Alabama, Huntsville, may help shape the future of concrete technology.

The NASA space shuttle program offers a payload carrier where small experiments can fly into orbit in the cargo bay of a space shuttle. This program offers experimenters the opportunity to perform research during extended periods of microgravity. The mortar was successfully mixed and cured on the shuttle.

Scientists produced a control mortar sample using the same equipment, mix components, and methods used on board the space shuttle, but hydrated and cured under the influence of gravity. Both the microgravity and control mortar samples underwent petrographic examinations which indicate they have similar physical features. However, the control sample contains some air voids while the microgravity sample does not. Optical and scanning electron microscopy also revealed that the space mortar has more visible crystalline hydration products, uniform in size and distribution throughout the matrix, than does the control sample.