BSE‐IA reveals retardation mechanisms of polymer powders on cement hydration

Abstract

The retardation effects of two polymer powders, styrene butadiene rubber and ethylene‐vinyl acetate, on cement hydration and the mechanisms in terms of hydration degree and microstructure characteristics were investigated by the combination of backscattered electron image analysis, scanning electron microscopy, energy dispersive spectrometer, and X‐ray diffraction. Results show that the cement hydration can be significantly retarded by both polymers with the reductions in cement hydration degrees and hydration products thickness. Polymers retard cement hydration by agglomerating the polymer particles on the surfaces of cement grains, forming films in different thickness and bonding the calcium ions in the pore solutions. Consequentially, the formation of C‐S‐H and CH is depressed and the Ca/Si ratios in the hydration product layer are raised. The retardation is enhanced with the increase in polymer content. This work helps understand the retardation effect of polymers on cement hydration in depth, which enables rational development of polymer‐modified cement‐based materials for further applications.

Enhancement of water and salt penetration resistance into mortar cement composited with vulcanized natural rubber compound

“…As demonstrated in Figure 4f(1‐2) and g(1‐2), thick rubber films inserted between bonding of calcium silicate hydrate (CSH) and calcium hydroxide (CH) emerged, consistent with the sketches in Scheme 5b,d. However, there were disadvantages to using an excessive amount of vulcanized natural rubber compound 45,46 . An excessive amount of vulcanized natural rubber was added to the mortar composite samples due to the attachment of vulcanized rubber particles within the samples caused to fracture, resulting in increased porosities.…”

“…However, there were disadvantages to using an excessive amount of vulcanized natural rubber compound. 45,46 An excessive amount of vulcanized natural rubber was added to the mortar composite samples due to the attachment of vulcanized rubber particles within the samples caused to fracture, resulting in increased porosities. Because the differential thermal expansion coefficient values between vulcanized natural rubber and mortar cement paste are $2.20 Â 10 À4 ( C) À1 and 18 Â 10 À6 ( C) À1 , respectively.…”

Pervious concrete with secondarily recycled low-quality brick-concrete demolition residue: Engineering performances, multi-scale/phase structure and sustainability

“…12. Within the same mechanisms of phase reorganization in XCT, in BSE images, a phase with higher density (or higher atomic number) is also displayed in a higher brightness (Peng et al, 2020;Zeng et al, 2021). So it is easy to identify the pores with the lowest brightness, the natural aggregate with the highest brightness, and the BCDR particles with the medium brightness (Fig.…”

“…XCT, as a non-destructive testing technique, has been widely used to characterize the pore structure (Zeng et al, 2020), explore the relationship between pore size and mechanical properties Zhou et al, 2019), and analyze the pore connectivity and the paths for simulating the seepage of pervious concrete . Here, an industrial XCT device of XTH255/320 LC (Nikon, Japan) was applied for XCT scans.…”

Delayed Absorption Superabsorbent Polymer for Strength Development in Concrete

“…The results are shown in Figure 7. The volume fraction of unhydrated cement was determined by brightness separation [49], and the average of the three samples is shown in Figure 7B. The volume ratio of unhydrated cement is lower in the region 50 µm from the SAP surface than above it.…”