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Recycled glass power can be used to as a partial precursor in alkali‐activated slag (AAS) cement binder. The municipal glass power was processed with sizes of 30‐50 μm and applied with 15% and 20% replacement ratio of slag cement for AAS sample preparation. To increase the usage of recycled glass particles, the AAS mortar was then prepared by extending glass powder modified AAS binder and applying 25% glass particles in sieving size #8‐#16. The recycled tire steel fibers (RSF) were also used in the AAS mortar as enforcement. The results showed the glass powder modified AAS binder has comparable compressive strength and early‐stage shrinkage deformation with limited reduction. The applied glass particles in mortar samples showed slightly reduced compressive strength and also reduced shrinkage deformation. Finally, the RSF reinforcement in glass powder and particle modified AAS mortar can largely improve the compressive, tensile and flexural strength. The magnetic polar interaction between the recycled tire steel fibers and slag cement lead to strong bonding behavior and thus contributes to the strength improvement. These results can facilitate the recycling of municipal glass power and particles in AAS binder and mortar, and also demonstrate that the added tire steel fibers can largely improve the fracture strength and properties of AAS mortar.

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Alternative binder chemistries, such as calcium sulfoaluminate (CSA) cements, often require admixtures to achieve set-time and workability requirements. A common carboxylate retarder for CSA cement, citric acid, is compared against a series of phosphono-group compounds for both retarding and workability capability. X-ray diffraction, pore solution analysis, and adsorption analysis were analyzed to understand the early hydration phase formation and retardation mechanism by each retarder utilized. While citric acid maintained the longest Vicat set time, it was found through mini-slump experiments that phosphono-based chemistries maintained higher mini-slump spreads compared to citric acid.

Belitic calcium sulfoaluminate cement is a fast setting, fast strength gain alternative cement that has some advantages which make it a good structural material. Because it is a low shrinkage cement it is a great choice for structural repairs. BCSA cement's fast strength gain also makes it a good choice for precast concrete. This presentation details past work on the use of belitic calcium sulfoaluminate cement in structures. The flexural and shear behavior of reinforced concrete beams made with BCSA cement will be described including comparisons with building code equations and with portland cement concrete. Finally, an update on ongoing work on structural concrete repairs made with BCSA cement will be given.

A substantial fraction of fly ash co-mingled with flue gas desulfurization (FGD) products are discarded as off-specification materials due to exceeding the 5.0% SO3 content limit specified in ASTM C618. As such, it is expected that fly ash harvested from some landfills and ponds will have high SO3 content. The behavior of these fly ashes in cementitious systems varies significantly depending on the type of sulfur present in the ash including calcium sulfate, calcium sulfite, and sodium sulfate. As such, a single SO3 content limit specified in ASTM C618 is not sufficient to capture their complexity or performance. Four off-specification FGD co-mingled fly ash products were investigated in this study. This included evaluating their impact on workability, setting time, pore solution pH, compressive strength, and expansion in lime water using paste and mortar mixtures at 20% cement replacement level. Advanced characterization techniques such as X-ray diffraction, isothermal calorimetry, and pore solution analysis using inductively coupled plasma atomic emission spectroscopy were also used to study the hydration behavior of blended systems containing these ashes. The results of this study have been used to identify appropriate beneficiation options and potential modifications to the specifications.

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