In this work, the effects of raw algal biomass on the hydration kinetics of portland cement are reported. Specifically, direct addition of 0.3%, 0.5%, 1.0%, and 3.0% photosynthetic Chlorella algal biomass to cement paste substantially delayed cement hydration, as indicated by 16.5%, 29.4%, 82.4%, and 812% delays in the main peak of heat evolution measured by isothermal calorimetry. Retardation was confirmed via FTIR to be mechanistically caused by the existence of −COOH and −OH functional groups in raw algae. We substantiated the observation that elimination of −COOH and −OH functional groups in the algae through heat treatment coincided with the disappearance in the retardation effect, while enhancement of these functional groups through H 2 O 2 treatment induced further retardation. In addition, the effects of untreated and treated algae on the morphology, mineralogy, and compressive strength of cement pastes containing 0.5% Chlorella were found to be negligible. An addition of 0.5% algal biomass is estimated to cost approximately USD $1.6−2.6/m 3 of concrete, suggesting that raw algae could be used as a renewable, cost-competitive, CO 2 -storing set-retarding admixture for portland cement-based materials.

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This study analyzed 95,000 overweight (OW) single-trip truck permits issued in Wisconsin between May 2007 and June 2013. A geographic information system and relational databases were used to conduct a statewide routing analysis to identify highways that are heavily used by OW permitted trucks, such as WI-140. Field studies at WI-140 confirmed a high proportion of OW trucks. In addition, pavement damage and deterioration caused by heavy truck traffic were investigated by conducting a visual distress survey and determination of the pavement condition index (PCI). The pavement of WI-140 was heavily distressed, with a PCI description of very poor. The Mechanistic–Empirical Pavement Design Guide (MEPDG) was used on WI-140 to evaluate the performance of the pavement under OW truck traffic. The results of the MEPDG analysis showed that the pavement was heavily distressed and deteriorated, a condition that was consistent with field measurements and observations. A primary application of the routing and pavement analyses is to assist the Wisconsin Department of Transportation in developing rehabilitation strategies for deteriorated pavements.

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