Materials Analysis and Research Laboratory - Research

While much effort at MARL is spent aiding others in their research, there are several research areas in which the MARL staff have a direct interest.

Durability of concrete

There are ongoing projects aimed at characterizing concrete microstructure, the factors that determine it, and the the influence of that structure on the durability of the concrete. For the last few years, the Iowa Department of Transportation has supported research at MARL examining the pore structure of concrete as it affects its durability as a road surface.

The laboratory has developed and continues to develop techniques for characterizing the concrete. Concrete is not normally observable in an electron microscope since the low vacuums of a conventional SEM will dehydrate the concrete and crack the specimen. Therefore, the Hitachi S-2460N SEM was acquired with the express intent of using it to examine concrete samples.

Sample preparation, image acquisition, and image analysis techniques continue to undergo development in order to obtain quick and accurate information about the pore structure.

Aggregate characterization

The quality of limestone and dolomite aggregate used in concrete production has been shown to significantly affect the durability of the concrete. MARL in conjunction with the Iowa DOT is employing thermal analysis techniques (DTA) and elemental analysis techniques (XRF) to characterize limestones and to correlate those characteristics with service record.

Fly ash characterization

Much of the fly ash produced by burning coal for electrical power generation is finding its way into the construction industry. Fly ash has a natural pozzolonic tendency, i.e., it is a natural cement. Therefore, it is being used to supplement or partially replace Portland cement in many applications. However, the suitability of a given fly ash is dependent on its chemistry which is determined by the coal or mixture of coals from which it comes and the conditions under which it was produced. MARL is involved with characterizing fly ash chemistry using x-ray fluorescence (XRF) and with characterizing its strength with actual test specimens.