Effect of Sonicated Deionized Water on The Early Age Behavior of Portland Cement-Based Concrete and Paste
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Assi, Lateef N. (ORCID:0000000282596543)↗
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Results for “Portland”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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The spatial and temporal evolution of the Portland and Tualatin forearc basins, Oregon, USA
The Portland and Tualatin basins are part of the Salish-Puget-Willamette Lowland, a 900-km-long, forearc depression lying between the volcanic arc and the Coast Ranges of the Cascadia convergent margin. Such inland seaways are characteristic of warm, young slab subduction. We analyzed the basins to better understand their evolution and relation to Coast Range history and to provide an improved tectonic framework for the Portland metropolitan area. We model three key horizons in the basins: (1) the top of the Columbia River Basalt Group (CRBG), (2) the bottom of the CRBG, and (3) the top of Eocene basement. Isochore maps constrain basin depocenters during (1) Pleistocene to mid-Miocene time (0–15 Ma), (2) CRBG (15.5–16.5 Ma), and (3) early Miocene to late Eocene (ca. 17–35 Ma) time. Results show that the Portland and Tualatin basins have distinct mid-Miocene to Quaternary depocenters but were one continuous basin from the Eocene until mid-Miocene time. A NW-striking gravity low coincident with the NW-striking, fault-bounded Portland Hills anticline is interpreted as an older graben coincident with observed thickening of CRBG flows and underlying sedimentary rocks. Neogene transpression in the forearc structurally inverted the Sylvan-Oatfield and Portland Hills normal faults as high-angle dextral-reverse faults, separating the Portland and Tualatin basins. An eastward shift of the forearc basin depocenter and ten-fold decrease in accommodation space provide temporal constraints on the emergence of the Coast Range to the west. Clockwise rotation and northward transport of the forearc is deforming the basins and producing local earthquakes beneath the metropolitan area.
15 GEOTHERMAL ENERGY↗
Portland Urban Development: Quantifying and Visualizing Urban Heat with Compounding Vulnerabilities to Support Community Depaving Initiatives
Urban heat is a pressing concern in Portland, Oregon as climate change induced heat waves increase. Cities experience higher temperatures due to the urban heat island effect (UHI), and environmental injustice and disenfranchisement in minority communities expose low-income and Black, Indigenous, and People of Color (BIPOC) residents to more extreme and debilitating heat events. Our team identified Portland’s communities on the frontlines of urban heat impacts by overlapping environmental and social vulnerabilities using NASA Earth observations. We partnered with Depave, a Portland-based nonprofit that works alongside communities to replace pavement with greenspace in historically disenfranchised areas. Using Landsat 8 Thermal Infrared Sensor (TIRS) imagery, we mapped Land Surface Temperature (LST) and developed a heat-specific Social Vulnerability Index (SVI) through a Principal Component Analysis (PCA) to identify Portland’s communities with the highest potential heat vulnerability. Then, we calculated the temperature change of depaving in six case studies to quantify Depave's efforts in heat mitigation and environmental justice. Our analysis demonstrated that, throughout Portland, there are frontline communities experiencing high potential social vulnerability to extreme temperatures due to environmental injustices and over-pavement. Finally, Depave’s impact on urban heat is observable and quantifiable using remote-sensing data and tools, with an average of 1ºF LST decrease across the six case studies. We illustrated the significance of local urban heat mitigation efforts and propose next steps for conducting inclusive and intentional research that highlights the lived experiences and resilience of frontline communities.
Environmental justice↗
An Integrated Feasibility Study of Reservoir Thermal Energy Storage (RTES) in Portland, OR, USA
In regions with long cold overcast winters and sunny summers, Deep Direct-Use (DDU) can be coupled with Reservoir Thermal Energy Storage (RTES) technology to take advantage of pre-existing subsurface permeability to save summer heat for later use during cold seasons. Many aquifers worldwide are underlain by permeable regions (reservoirs) containing brackish or saline groundwater that has limited beneficial use due to poor water quality. We investigate the utility of these relatively deep, slow flowing reservoirs for RTES by conducting an integrated feasibility study in the Portland Basin, Oregon, USA, developing methods and obtaining results that can be widely applied to RTES systems elsewhere. As a case study, we have conducted an economic and social cost-benefit analysis for the Oregon Health and Science University (OHSU), a teaching hospital that is recognized as critical infrastructure in the Portland Metropolitan Area. Our investigation covers key factors that influence feasibility including 1) the geologic framework, 2) heat and fluid flow modeling, 3) capital and maintenance costs, 4) the regulatory framework, and 5) operational risks. By pairing a model of building seasonal heat demand with an integrated model of RTES resource supply, we determine that the most important factors that influence RTES efficacy in the study area are operational schedule, well spacing, the amount of summer heat stored (in our model, a function of solar array size), and longevity of the system. Generally, heat recovery efficiency increases as the reservoir and surrounding rocks warm, making RTES more economical with time. Selecting a base-case scenario, we estimate a levelized cost of heat (LCOH) to compare with other sources of heating available to OHSU and find that it is comparable to unsubsidized solar and nuclear, but more expensive than natural gas. Additional benefits of RTES include energy resiliency in the event that conventional energy supplies are disrupted (e.g., natural disaster) and a reduction in fossil fuel consumption resulting in a smaller carbon footprint. Key risks include reservoir heterogeneity and a possible reduction in permeability through time due to scaling (mineral precipitation). Lastly, a map of thermal energy storage capacity for the Portland Basin yields a total of 43,400 GWh, suggesting tremendous potential for RTES in the Portland Metropolitan Area.
14 SOLAR ENERGY↗
Pushing Green: Leveraging Home Energy Score to Promote Deep-Energy Retrofits in Portland, Oregon
In the United States, 39% of total energy is consumed by the building sector, 20% of which is attributed to residential buildings. Older homes, built before 1992 when the U.S. Department of Energy’s (DOE) Building Energy Codes Program was established, represent approximately 68% of residential building stock in the country and often have significant air leakage, inadequate insulation and inefficient heating & cooling systems. These older homes have long been the elephant in the room: how can programs effectively increase efficiency in all of the homes in need? Developed by DOE, the Home Energy Score was established to provide homeowners, buyers, and renters a comparable score measuring a home's energy use. Much like the MPG rating of automobiles, the Home Energy Score provides an overview of a residential building’s energy efficiency. In 2016, the City of Portland passed an ordinance requiring all residential properties to receive a Home Energy Score before being listed for sale, a mandate that was implemented January 1, 2018. Since 2018, more than 22,000 homes throughout the Portland Metro area have received Home Energy Scores (amounting to over 10% of Portland's single-family homes). This paper explores the sample of Home Energy Scores throughout Portland, including at the neighborhood level, identifies trends in efficiency measures, describes how the data has been used to date and proposes ways program administrators can use the Home Energy Score to increase the impact of energy efficiency programs on a city-scale.
Antonopoulos, Chrissi A.↗
Comparison on the properties of ITZs in fly ash-based geopolymer and Portland cement concretes with equivalent flowability
Highlights: • Modelled ITZs can effectively avoid the effects caused by different factors and test locations of ITZ. • ITZ properties of PC and geopolymer concretes are compared based on equivalent flowability of binders. • Geopolymer ITZ exhibits stronger bonding than that of PC, and higher mechanical properties than geopolymer paste. • Strong ITZs in geopolymer concrete are attributed to the layer of gel-rich paste with dense microstructures. • Elastic modulus and hardness properties of ITZs in PC concrete are increased due to the CH crystals. This paper aims to compare the properties of interfacial transition zones (ITZs) in Portland cement (PC) concrete and geopolymer concrete. Portland cement and geopolymer pastes were designed with the equivalent flowability to provide similar mix and casting condition of ITZs. Two types of modelled ITZs were prepared to facilitate the nanoindentations across ITZs, microstructural characterization, and comparison on the properties of ITZs with less influential factors. The results showed that the interfacial bonding of ITZs between geopolymer matrix and aggregate is relatively stronger than the counterpart in the PC concrete. There is a high amount of crystalline hydration products in the ITZs of PC concrete, but a layer gel-rich paste with denser microstructures in the ITZs of geopolymer concrete. Additionally, the interface morphology and nanoindentation analysis indicate that the property of ITZs in the modelled geopolymer concrete is not poorer than that of the corresponding geopolymer paste.
36 MATERIALS SCIENCE↗
Connecting Risk and Resilience for a Power System Using the Portland Hills Fault Case Study
Active seismic faults in the Pacific Northwest area have encouraged electric utilities in the region to deeply contemplate and proactively intervene to support grid resilience. To further this effort this research introduces Monte Carlo (MC)-based power system modeling as a means to inform the Performance Based Earthquake Engineering method and simulates 100,000 sample earthquakes of a 6.8 magnitude (M6.8) Portland Hills Fault (PHF) scenario in the Portland General Electric (PGE) service territory as a proof of concept. This paper also proposes the resilience metric Seismic Load Recovery Factor (SLRF) to quantify the recovery of a downed power system and thus can be used to quantify earthquake economic risk. Using MC results, the SLRF was evaluated to be 19.7 h and the expected economic consequence cost of a M6.8 PHF event was found to be $\$180$ million with an annualized risk of $\$90,000$ given the event’s 1 in 2000 year probability of occurrence. The MC results also identified the eight most consequential substations in the PGE system—i.e., those that contributed to maximum load loss. This paper concludes that retrofitting these substations reduced the expected consequence cost of a M6.8 PHF event to $117 million.
24 POWER TRANSMISSION AND DISTRIBUTION↗
Graphene nanoplatelets reinforced cement as a solution to leaky wellbores reinforcing weak points in hydrated Portland cement with graphene nanoparticles improves mechanical and chemical durability of wellbore cements
In this work, to improve the performance of wellbore cement under subsurface environments, graphene nanoplatelets (GNPs) were added in various percentages to Class-H cement slurry. Microstructural characterization of cement slurries cured at 90 °C and 95% RH indicates that GNP modifies the microstructure of hydrated cement by reinforcing pore spaces. As a result, the mechanical properties, such as Young's modulus and axial peak stress, obtained from high temperature triaxial compression tests are significantly improved based on different percentages of added GNPs. Furthermore, the hydrated 1 × 2 inch GNP- Portland cement cores tested under simulated deep wellbore conditions of high-temperature and high pressure (HTHP), appear to have a ductile-like behavior, when compared to a typical brittle nature of Portland cement pastes. From our observations and published data on graphene resistance to fracture, GNP addition to cement is evidently enhancing the flexibility of cement. These improvements would reduce the risks associated with wellbore cement deterioration and a consequent leakage in fossil fuel production, geothermal energy production, CO 2 storage as well as long-term sealing materials in plugging and abandonment of all wellbores at the end of their service life.
36 MATERIALS SCIENCE↗
Sulfate Promotes Compact CaCO 3 Formation and Protects Portland Cement from Supercritical CO 2 Attack
Supercritical (sc) CO 2 in geologic carbon sequestration (GCS) can chemically and mechanically deteriorate wellbore cement, raising concerns for long-term operations. In contrast to the conventional view of “sulfate attack” on cement, we found that adding 0.15 M sulfate to the acidic brine can significantly reduce the impact of scCO 2 attack on Portland cement, resulting in stronger cement than that found in a sulfate-free system. Scanning electron microscopy revealed a decreased total attack depth in reacted cement in the presence of sulfate. With a newly defined minimum porosity term in reactive transport modeling, our model suggests that sulfate caused CaCO 3 to fill more nanopore spaces in the cement. Small angle X-ray scattering experiments also showed that sulfate can decrease the pore sizes of the carbonate layer. The results suggest that the interactions between sulfate and cement can generate a less porous CaCO 3 layer, which better resists acidic brine. Using this mechanism as a proof-of-concept, we tested the incorporation of sodium sulfate into Portland cement and synthesized new cement composites that show stronger resistance against scCO 2 attacks. Finally, these newly discovered interfacial interactions between CaCO 3 and sulfate provide new insights into engineering mechanically strong and green materials for safer GCS.
54 ENVIRONMENTAL SCIENCES↗
1994 Portland Household Travel Survey
The Portland Household Travel Survey was conducted under the auspices of the Oregon Department of Transportation to provide information suitable for gaining an in-depth understanding of the activity and travel behavior of both households in metropolitan areas and the individuals within those households. The first round of surveys collected household activity data from the four metropolitan planning organization areas around Portland, plus three extra counties (Marion, Polk, and Yamhill). A total of 11,762 households participated in this study. Each household member was asked to record any activity that lasted 30 minutes or longer, or any activity that required travel for the specified 48-hour period.
1Hz data↗
Autogenous formation and smart behaviors of nitrite- and nitrate-intercalated layered double hydroxides (LDHs) in Portland cement-metakaolin-dolomite blends
In this work, the influence of sodium nitrite (NaNO{sub 2}) and sodium nitrate (NaNO{sub 3}) corrosion inhibitors on the composition, structure, and chloride binding behaviors of layered double hydroxides (LDHs) formed in ternary ordinary Portland cement-metakaolin-dolomite (OPC-MK-DM) systems is studied. The results show that the nitrite and nitrate anions are preferably intercalated in the CaAl LDHs (AFm phases), but not in the MgAl LDHs (hydrotalcite-type phases) due to its limited formation in these ternary cementitious systems cured at ambient temperature. The autogenously formed nitrate- and nitrite-AFm phases are decomposed upon chloride exposure accompanied by Friedel's salts formation, potentially releasing corrosion inhibitive ions to the pore solution in a progressive manner. The NaNO{sub 2} and NaNO{sub 3} incorporation in ternary OPC-MK-DM binders marginally lowers chloride binding capacity but reduces its penetration resistance mainly due to pore coarsening. Nevertheless, a strong linear correlation can be established between the water-soluble and total chloride contents in ternary OPC-MK-DM systems, regardless of OPC replacement level and corrosion inhibitor incorporation.
36 MATERIALS SCIENCE↗
Comparison of liquid absorption-release of superabsorbent polymers in alkali-activated slag and Portland cement systems: An NMR study combined with additional methods
In this study, {sup 1}H low-field NMR was used to compare the liquid absorption-release behaviour of superabsorbent polymers (SAPs) in Portland cement (PC) paste, NaOH-activated slag (SH-AAS) paste, and water glass-activated slag (WG-AAS) paste. The liquid absorption of SAPs in the PC paste was lower than that in the SH-AAS paste and the WG-AAS paste. The liquid release was also faster, which was mainly due to the higher Ca{sup 2+} concentration in the pore fluid of the PC system. In the AAS system, although the Ca{sup 2+} concentration in the pore fluid was low, the Na{sup +} concentration was much higher than that in the PC system due to the activator. The Ca{sup 2+} in the PC system is an important factor affecting the swelling of SAPs, while in the AAS system, the swelling limitation of SAPs is the result of the combined effects of Ca{sup 2+} and Na{sup +}, with Na{sup +} being dominant.
36 MATERIALS SCIENCE↗
Effect of ZnO on the whiteness of white Portland cement clinker
The addition of ZnO to significantly improve the Hunter whiteness of white Portland cement (WPC) clinkers is introduced in this paper. The effects of ZnO on the whiteness of WPC were studied by chroma analysis, X-ray diffraction (XRD), the Rietveld method, hydration heat measurements and SEM-EDS. The results showed that adding ZnO increased the visible light reflectance, increased the brightness (L{sup ⁎}), and reduced the yellowness (b{sup ⁎}) of WPC clinker with high Fe{sub 2}O{sub 3}. Therefore, ZnO can increase the whiteness of WPC clinker. Zn was mainly distributed in the amorphous phase and unquantifiable crystalline phase (ACn), and then dissolved in the silicate phase. ZnO stabilized R-C{sub 3}S, reduced the crystallization of C{sub 3}A, and increased the ACn content. ZnO increased the amount of Fe in the ACn and minerals, thereby reducing the formation of C{sub 4}AF and improving whiteness. ZnO increased the accumulated heat of hydration but prolonged the induction period. This method provides a new approach for the WPC industry to broaden sources of raw materials and improve product quality.
36 MATERIALS SCIENCE↗
Probing the exact form and doping preference of magnesium in ordinary Portland cement clinker phases: A study from experiments and DFT simulations
Highlights: • The doping behaviors of Mg in OPC clinker phases were systematically studied. • About 1.3 wt% MgO enter OPC clinker phases by forming substitutional solid solutions. • In the 4 composed minerals, C{sub 3}S, C{sub 3}A and C{sub 4}AF can host more Mg ions than C{sub 2}S. • Mg ions prefer to replace Ca in C{sub 3}S, C{sub 2}S and C{sub 3}A while replace Fe and Ca in C{sub 4}AF. • Both the large structure distortions and formation energies governs the low solubility. A systematic study was performed to learn the exact existence form and doping behaviors of magnesium in ordinary Portland cement (OPC) clinker. Our results show that about 1.3 wt% MgO incorporates into OPC clinker phases by forming substitutional solid solutions while excess Mg accumulate and exist as periclase. Results from Rietveld refinement present a substitution preference in C{sub 3}S and C{sub 3}A over C{sub 2}S. More in-depth analyses from density function theoretical simulations show that in C{sub 3}S, C{sub 2}S and C{sub 3}A, the substitution occurs by replacing Ca while in C{sub 4}AF, it probably occurs by substituting Fe and Ca ions. The large structure distortions and sharp increase in formation energies with increasing MgO determines its low solubility. This work provides a clear understanding of the existence states and the intrinsic mechanism governing doping behaviors of Mg, thus should be very important in guiding the synthesis of OPC clinker by utilizing high-Mg limestone.
36 MATERIALS SCIENCE↗
Combined effect of NaAlO2 and NaOH on the early age hydration of Portland cement with a high concentration of borate solution
The early age hydration of ordinary Portland cement in 5 M borate solution, with or without the addition of NaAlO{sub 2} and/or NaOH, was investigated. Hydration was measured using calorimetry, X-ray diffraction, thermogravimetric analysis, {sup 11}B and {sup 27}Al magic angle spinning NMR analysis, and scanning transmission electron microscopy. The purpose of this study was to reveal the mechanisms behind the retardation caused by a high concentration borate solution and the restoration of hydration through the combined addition of NaOH and NaAlO{sub 2}. Amorphous ulexite, which formed on the surface of the cement particles and prevented the further dissolution of anhydrous phases, was identified as the retardation product. The mechanism of the combined addition of NaAlO{sub 2} and NaOH in overcoming retardation was to transform amorphous ulexite into B-AFt and gowerite (CaB{sub 6}O{sub 10}·5H{sub 2}O). Formation of gowerite is favorable because of the much higher boron immobilization capacity in weight percentage, comparing to usual boron-containing phases reported previously.
36 MATERIALS SCIENCE↗
Influence of curing temperature on belite cement hydration: A comparative study with Portland cement
Belite cements (BCs) could be a more sustainable binder than Portland cements (PCs) but adequate knowledge of the hydration features has still to be built. In particular, the mild curing hydration temperature effects have been extensively studied for PCs but not for BCs. This research was triggered by a previous work reporting improved mechanical strengths of BCs at higher curing temperatures. Here, we report the hydration characteristics of a BC at 20, 40 and 60 °C and compared to those of a typical PC. We have corroborated previous findings and used a multi-technique approach including Rietveld phase analysis, thermal analysis, calorimetry, silicon MAS-NMR, mercury intrusion porosimetry and chiefly synchrotron X-ray microtomography, to thoroughly understand the different behavior. In a nutshell, the improved mechanical performances at mild curing temperatures for BCs are mainly due to a much larger belite degree of reaction, with lower porosity coarsening of belite cements also playing a role.
36 MATERIALS SCIENCE↗
Physical-chemical-mechanical quantitative assessment of the microstructural evolution in Portland-limestone cement pastes exposed to magnesium sulfate attack at low temperature
The changes in structural integrity and microstructure of Portland-limestone cement pastes were investigated in the course of magnesium sulfate attack at low temperature. A deterioration front, consisting of three distinct layers (brucite, gypsum, leached cement matrix), swelled in time due to the expansive nature of the deterioration products, generating cracks and subsequently detaching from the sound cement matrix, continuously promoting the process. Gypsum and thaumasite characterized the leached matrix, which experienced extensive cross-linking of the aluminosilicate structures, as a result of decalcification and dealumination of the calcium silicate hydrates (C(A)SH), impairing the overall mechanical performance. CSH of low packing density was most severely affected by the process, as confirmed by the significant drop in nano-mechanical properties. The increased rate of deterioration with limestone content was tentatively attributed to the prevalent morphology of the CSH phase. Results were validated by thermodynamic simulations, indicating that the real systems did not reach equilibrium.
36 MATERIALS SCIENCE↗
Initial hydration process of calcium silicates in Portland cement: A comprehensive comparison from molecular dynamics simulations
As the main components of Portland cement, calcium silicates show substantial differences in their hydration reactivity which have not been fully explained. A comprehensive comparison of the initial hydration process of calcium silicates, namely dicalcium silicate (C{sub 2}S) and tricalcium silicate (C{sub 3}S), was conducted using molecular dynamics simulations. The initial hydration process was divided into three stages using cut-off times of 0.001 ns and 3 ns. The hydration of M{sub 3}-C{sub 3}S (010) was more evident than that of β-C{sub 2}S (100), supported by the hydroxylation degree, radial distribution function, atomic density profile, etc. The coordination number of the surface Ca atoms might be the underlying reason for such a difference. Interactions between cement surfaces and water molecules were mainly characterised by solid OH bonding and Ca-water O bonding. Dissolution of Ca atoms was observed, although quite scarce, while no dissolution of Si atoms was observed.
36 MATERIALS SCIENCE↗