Browsing by Subject "Waste management"

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BIM-based construction waste management and circular economy for resource recovery
(2021-04-21) Guerra, Beatriz Chinelato; Leite, Fernanda L.; Felkner, Juliana; Faust, Kasey; Ferron, Raissa
Projections show that the consumption of raw materials worldwide is set to almost double by 2060, and the construction industry is a key responsible party for this trend. Additionally, high generation of construction and demolition waste is a common trend in the construction industry. Engineering challenges related to the aforementioned trends are identified in different phases of a construction project lifecycle. For instance, the difficulty in estimating construction waste (CW) generation in the early phases of a project and the lack of formal planning of CW reuse and recycling (R&R) during construction further challenges the waste generation issue. Moreover, early disposal of the existing built environment, with low recovery of resources are challenges associated to the end-of-life of projects that tend to aggravate the consumption of natural resources. Three research questions in this PhD dissertation sought to aid the aforementioned engineering challenges. Research Question 1 is tied to the problem of CW generation estimation during early phases of the project; as such, algorithms leveraging Building Information Modeling (BIM) were developed to automate and streamline CW generation estimations. BIM was used due to its capabilities of fast and reliable retrieval of project data. Research Question 2 built on Research Question 1 algorithms, but went one step further and discretized the amounts of CW generation into quantities for on-site reuse and off-site recycling. Four-dimensional (4D) BIM – through its simulation and visual capabilities – was used to enhance CW R&R planning during construction. Formalizing and enhancing CW R&R planning promotes resource recovery and minimizes waste disposal in landfills. Finally, Research Question 3 focused on the resource recovery issue at the end-of-life of a project, and the design of new building construction; this research sought to better understand the application of strategies that facilitate the circulation of resources in the United States built environment. Notably, contributions of this dissertation include streamlining the application of construction waste management practices (i.e., CW generation estimation and CW R&R planning) at the project level, and providing an overview of key construction industry stakeholders’ awareness and adoption of circular construction strategies in the United States.
Effects of solar heating and insulation on model biodigester temperature
(2022-07-29) Leigh, Rush; Ellzey, Janet L.; Mullett, John
Biodigesters are important tools for the faecal sludge management in developing countries and in emergency situations such as refugee camps. The effectiveness of biodigesters, however, is limited by local circumstances such as infrastructure issues, skilled labor shortages, and most importantly for this project: lack of temperature control of the biodigester. This thesis delves into the state of the art of biodigesters deployed in emergency situations, identifies many of the specific problems with biodigester effectiveness, and focuses on the importance of regulating the temperature of the biodigester. The primary question addressed by the research is: Can insulation and heating provided by photovoltaic panels (PV) effectively maintain a biodigester (of differing sizes and environmental conditions) within the temperature range for mesophilic digestion (35℃ to 37℃)? Starting with physical experimentation, data was collected from small scale mock biodigesters, under different conditions (e.g., covered by a tarp vs. uncovered, insulation vs. no insulation). Using heat transfer equations, a computational model was developed and compared to experimental data, in order to validate the model. The model results showed good agreement with the experimental measurements in all cases studied. For all experiments, the average difference between the model and actual data was less than 1°C, with the exception of one experiment (Heated vs. Heated Model), which had an average difference of less than 2°C. Using the validated model, four predictive cases were created: (1) Flexigester in coastal climate; (2) Flexigester in seasonal climate; (3) Anaerobic Lagoon in coastal climate; (4) Anaerobic Lagoon in seasonal climate. The scale of the flexigester is approximately 30 m³, and the Anaerobic Lagoon is 1,400 m³. These cases revealed the necessary amount of insulation and number of solar panels necessary to maintain the temperature within the desired range. Although exacts costs are not possible to obtain from these simulations, the results can still be used to determine the cost of the specified amount on insulation and number of solar panels. The estimated costs for retrofitting the four biodigester cases with insulation and solar panels to achieve optimal temperature ranges for mesophilic digestion are as follows: (1) $825, (2) $1,875, (3) $33,750, (4) $78,750. In summary, insulation in combination with heating provided by PV is a promising approach for maintaining biodigesters at optimal temperatures.
Evaluation of engineering properties of drill cuttings for construction materials
(2023-08-25) Mena Arango, Karen E.; Gilbert, Robert B. (Robert Bruce), 1965-; El Mohtar, Chadi Said
This research arises my motivation as an opportunity to evaluate one of the applications for drill cuttings in the construction industry and thus contribute to the reduction of the environmental hazard that may affect human health and the environment. The main objectives of this study are 1) Investigate the potential use of drill cuttings disposed on a specific site as embankment fill materials; 2) Provide input for drill cuttings characterization regarding engineering and environmental properties; 3) Perform leachability tests on drill cuttings to determine their potential of leaching Total Organic Content as the water circulates through a soil column; 4) Evaluate the impact that lime and organoclay may have on the engineering and environmental properties of drill cuttings. The methodology of this research included site visits, sampling, and laboratory tests for the material characterization, such as particle size distribution, Atterberg limits, moisture content, compaction, unconfined compressive strength, pH, Oxidation Reduction Potential, and Total Organic Content. From working on this research, it was possible to conclude that 1) The results of material characterization for the sampled drill cuttings indicate an average natural moisture content of 21%, neutral pH, the material classification corresponds to Clayey Sand (SC), with an average Liquid Limit of 35% and an average Plasticity Index of 17%; 2) The results for engineering properties for the sampled drill cuttings indicate an optimum water content of 19% and maximum dry density of 100 pcf when compacted with comparable energy for embankment fills, TxDOT 114 or Standard Proctor compaction. The unconfined compression strength when the material is compacted to its maximum dry density with Standard Proctor compaction averages 22 psi; 3) The Oxidation Reduction Potential (ORP) of the sampled drill cuttings, as per the leaching test (EPA 1314 Method), reached an average of 218 mV at a cumulative liquid-to-solid ratio (L/S) of 10; 4) The cumulative Total Organic Content (TOC) at the end of the leaching tests (EPA 1314 Method) for the sampled drill cuttings indicates an average of 0.35 mg/g of solids for drill cuttings and an average of 0.21 mg/g of solids for the mixes with 5% of organoclay; 5) The addition of lime to the sampled drill cuttings does not show any significant benefit that could promote its use with these materials. The addition of organoclay tends to increase the Oxidation Reduction Potential (ORP) and reduce the Total Organic Content. According to the solubility control line on the cumulative release curve, the sampled drill cuttings mixed with 5% organoclay by weight show a low potential to leach into the environment under landfill conditions. These results indicate good potential to amend the sampled drill cuttings with organoclay in order to improve their suitability for use as embankment fill material if leaching is a concern. Further research is recommended to 1) Determine the type and optimum stabilizer content to meet the plasticity index and compressive strength requirements for roadway construction; 2) Investigate the effect of organoclay and other binders over time after mixing with drill cuttings.