Comparative strength testing was conducted using a rebound hammer technique. The test was selected for convenience and being able to represent and describe change noted in concrete following application of GPHP. Compressive strength is a key concrete property relied upon to prevent wear and resist deterioration in the most direct way. Increase in compressive strength signifies increase in durability and wear resistance of pavement due to application of GPHP.
Relative water permeability testing was conducted using a Germann Instruments GWT method which applies static pressure to a confined area to calculate absorption volume over time. Permeability is a key concrete condition describing in general terms concrete porosity and indicating the possibility of chemical (chloride) contamination and carbonation. Generally speaking less permeable concretes have longer lifespan. Water permeability results were compared before and after application of GPHP to show change. pH was determined using a Germann Instruments pH Rainbow Indicator spray. Rainbow indicator shows surface pH by changing color. pH test is always conducted on the freshly open concrete surface. During work within the scope of this report pH measurement (carbonation) is used as a general indication of concrete deterioration and while in itself does not in this case represent a critical property is an indicator of deterioration progress and could be used as means of comparison before and after application of GPHP.
During the project GPHP was applied to all test areas by low pressure spraying. Brushing was used to distribute material evenly as well as break up the surface tension to encourage penetration. Area 1 was selected as an example of the drive section of the pavement. Areas 2 and 3 represent general airfield condition.Surface loss, exposed steel fibers, exposed coarse aggregate are present in all three locations.