Using Image Analysis to Improve Understanding of Grout Stability Using Column Bleed Testing-Paper

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The study evaluates image analysis as a practical way to assess grout stability beyond the conventional column bleed test, which measures only the clear water separating at the top after two hours. That single measurement can miss substantial changes in grout concentration throughout the column, especially when superplasticizers (SP) are used.<br /><br />Researchers tested microfine cement grouts with water-to-cement ratios of 1.5:1 and 3:1 and varying SP dosages. They photographed grout columns under controlled lighting, analyzed color intensity with ImageJ, and calibrated intensity against water-to-cement ratios measured by manual pipette sampling and drying. Image analysis provided continuous profiles of concentration over the column height and time, while pipette measurements averaged results over fixed sections.<br /><br />The results showed that increasing SP altered how grout settled. Without SP or at low dosages, a relatively clear boundary formed between bleed water and more uniform grout. At higher dosages, suspended particles created a cloudy upper layer and increasingly gradual concentration changes. At 2.5% SP and above, visible clear-water bleed was limited, yet the grout was highly nonuniform: much of the column had a water-to-cement ratio above the original mix, while the bottom became more concentrated. This behavior could make a grout appear stable by conventional bleed criteria even when its composition varies substantially.<br /><br />Image-analysis profiles generally agreed with manual measurements while revealing sharper and more detailed changes. The authors conclude that clear-water bleed alone can be misleading, particularly in mixes containing SP. With an appropriate calibration, image analysis offers a low-effort method for tracking grout concentration over time and height, improving understanding of stability and potentially informing grout design and quality control.

Keywords

grout stability

image analysis

column bleed test

superplasticizer

microfine cement

water-to-cement ratio

bleed water

ImageJ

grout concentration

quality control