Data of The Shard Test and Nanoporomechanics Reverse the Classical Paradigm of Cement Hydration Being Contractive

Description

For a century, the chemical hydration of cement has been considered a contractive process. This behavior occurs in the nanoscale hydration of cement particles with water, producing a smaller volume of hydration products. The cement hydration of the colloidal cement system generates a shell of hydration product surrounding the inner anhydrate particle. After the initial shell is created, the diffusion drives water into the inner anhydrate cement, and the internal growth of new hydration produces crystal growth pressure. A new experiment procedure shows chemical expansion above the nanoscale. Cement paste slabs that are 0.5 mm thick show volumetric expansion when exposed to full saturation by submerging them in water. In contrast, the identical cement paste slabs are 0.5 mm thick show volumetric contraction due to self-desiccation when submerged in paraffin oil. The topography of the concrete slabs submerged continuously in water or paraffin oil is measured using the Olympus 3D Laser Confocal Microscope as time evolves. The Raw Data Confocal Microscoper (Not Trimmed) folder shows the following: STL files for the measured topography for five samples per each day. The Trimmed Data Confocal Microscope folder shows the trimmed .STL samples for the five samples after using Meshmixer to remove the petri dish and the carbon tape from the specimens' surface topography. The point cloud .ply is saved from the trimmed .stl file. The MatLab Code Volume Integration Scheme folder shows the volume calculation under the surface of the point cloud .ply. The MatLab Code divides the X and Y coordinates into infinitesimal grids. Then, it locates all the point cloud points inside the grid and calculates their average height in z direction [f (i,j)]. Finally, the volume is the sum of the infinitesimal prisms with delta_V = f(i,j) * delta_x * delta_y. The Analysis Summary folder shows the Excel spreadsheet with the summary of the measurement of both systems for the five specimens. The volume not presented in the sheet for individual days is due to an error in acquiring the laser raw data.

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