Shape and Size of Particles Scaled from Concrete Surfaces during Salt Frost Testing and Rapid Freeze/thaw in Water

Abstract

Thickness (T), Length (L), Width (W) and size distribution of scaled concrete particles in frost testing were measured. T (mm) increases with particle size surprisingly similarly for different concrete qualities and frost test methods. 2T/(L+W) reduces as function of size and is lowest for the largest particles of the salt scaling test: 0.1 – 0.15 but increases if large aggregate particles scale. Particle size distributions from salt frost testing peak for particles of 1-2 mm. The particles are flakier compared to particles from freeze/thaw in water which also have flatter size distribution no matter type of concrete or degree of damage. Scaling in water is not so efficiently reduced by air voids despite protecting very efficiently against internal damage and scaling in salt frost testing. Comparisons with T predicted by the glue spall model (≈3/4 × ice thickness) and the air void dependent (≈3× critical air void spacing) model proposed by Fagerlund are difficult due to the size dependent flake thickness. Image analysis could well describe shape. Further studies of concrete flake thickness scaled at varying thickness of ice layers are proposed.

Nordic Concrete Research workshop: “Accelerated freeze-thaw testing of concrete”, Lyngby, 20th April 2022

“…Despite of that the geometry of the flakes can be linked to the damage mechanism, this has caught very little attention before a M.Sc. project carried out at NTNU (described in more detail in [14]). In this project, scaled material from standardised freeze-thaw testing was collected and sieved.…”

“…A methodology was developed to measure thickness, length, and width of the flakes, see Figure 9. [14]).…”

“…Bottom, right: Digital photos taken perpendicular and parallel to the surface of the steel bar made it possible to determine thickness (T), length (L) and width (W) of the individual flakes accurately. (Illustrations from[14]).…”

The Synthesis and Performance of a Novel Lignin Modified Salt-Resistant Branched High-Performance Water Reducer

“…This study is still in its early stages, and there is no relevant research yet. The available salt-resistant water reducer literature is mostly about the resistance of erosion of concrete by sulfate and chloride salts after being added [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ], rather than to improve its fluidity during construction.…”

The Synthesis and Performance of a Novel Lignin Modified Salt Resistance Branched High-Performance Water Reducer

“…This study is still in its early stages, and there is no relevant research yet. The available saltresistant water reducer literatures are mostly about resistance of erosion of concrete by sulfate and chloride salts after being added [10][11][12][13], rather than to improve its fluidity during construction. Starting from the multi-hydroxyl lignin, a salt resistance branched high-performance water reducer (BHPWR) was prepared by introducing branching structures.…”