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41-529: South Lake Avenue / Minnesota Avenue serves as a main route in the community. Near the end of Minnesota Point is a small airport, Sky Harbor Airport . Beyond the airport, approximately 3/4 mile, is an old growth red and white pine forest. Within the forest is a Minnesota Department of Natural Resources designated area, the Minnesota Point Pine Forest Scientific and Natural Area , which encompasses 18 acres. Minnesota Point

82-402: A binder. The abbreviation, AC , is sometimes used for asphalt concrete but can also denote asphalt content or asphalt cement , referring to the liquid asphalt portion of the composite material. Mixing of asphalt and aggregate is accomplished in one of several ways: In addition to the asphalt and aggregate, additives, such as polymers , and antistripping agents may be added to improve

123-465: A coffee shop and a complex for pickleball, basketball and street hockey. 46°44′29″N 92°03′41″W  /  46.74139°N 92.06139°W  / 46.74139; -92.06139 Sky Harbor Airport %26 Seaplane Base Sky Harbor Airport & Seaplane Base or Sky Harbor Airport ( ICAO : KDYT , FAA LID : DYT ) is a public airport in Duluth , Minnesota , United States . It

164-635: A hard surface runway for airplanes and water landing areas for seaplanes. Although most U.S. airports use the same three-letter location identifier for the FAA and IATA , Sky Harbor Airport is assigned DYT by the FAA but has no designation from the IATA. Sky Harbor Airport covers an area of 70 acres (28  ha ) which contains one asphalt paved runway designated 14/32 which measures 2,600 by 75 feet (793 x 23 m). It also has two seaplane landing areas: 9W/27W

205-441: Is 5,000 by 1,500 feet (1,524 x 457 m) and 13W/31W is 10,000 by 2,000 feet (3,048 x 610 m). Protecting old-growth pine trees on the south east end of the runway prompted a $ 13.2 million project which realigned the runway by 5 degrees and changed the runway length to 2600 feet with no displaced thresholds. The airport reopened with its newly resurfaced runway on June 12, 2020. The runway realignment created seven acres of new land for

246-454: Is a maintenance measure that helps keep water and petroleum products out of the pavement. Maintaining and cleaning ditches and storm drains will extend the life of the road at low cost. Sealing small cracks with bituminous crack sealer prevents water from enlarging cracks through frost weathering, or percolating down to the subbase and softening it. For somewhat more distressed roads, a chip seal or similar surface treatment may be applied. As

287-776: Is a research program by the FHWA , which is specifically focusing on long-term pavement behaviour. Asphalt deterioration can include crocodile cracking , potholes , upheaval, raveling , bleeding , rutting , shoving, stripping , and grade depressions. In cold climates, frost heaves can crack asphalt even in one winter. Filling the cracks with bitumen is a temporary fix, but only proper compaction and drainage can slow this process. Factors that cause asphalt concrete to deteriorate over time mostly fall into one of three categories: construction quality, environmental considerations, and traffic loads. Often, damage results from combinations of factors in all three categories. Construction quality

328-600: Is about 7 miles long, and when included with adjacent Wisconsin Point , which extends 3 miles out from the city of Superior , Wisconsin , totals 10 miles. Due to the short and easy portage across Minnesota Point, the Ojibwe name for the city of Duluth is Onigamiinsing ("at the little portage"). In the 1850s, the Saint Louis River was established as the border between neighboring states Minnesota and Wisconsin and

369-415: Is critical to pavement performance. This includes the construction of utility trenches and appurtenances that are placed in the pavement after construction. Lack of compaction in the surface of the asphalt, especially on the longitudinal joint, can reduce the life of a pavement by 30 to 40%. Service trenches in pavements after construction have been said to reduce the life of the pavement by 50%, mainly due to

410-473: Is found on interstate highways where maintenance is highly crucial. Asphalt concrete generates less roadway noise than a Portland cement concrete surface, and is typically less noisy than chip seal surfaces. Because tire noise is generated through the conversion of kinetic energy to sound waves , more noise is produced as the speed of a vehicle increases. The notion that highway design might take into account acoustical engineering considerations, including

451-594: Is located near the Wisconsin border, between Superior Bay and Lake Superior . The airport is six nautical miles (11 km) southeast of the central business district of Duluth, Minnesota , on Minnesota Point within its city limits. The airport is owned by the Duluth Airport Authority and has been operating for over 50 years. It is one of only four airports in Minnesota offering both

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492-420: Is why some agencies place the priority on preventive maintenance of roads in good condition, rather than reconstructing roads in poor condition. Poor roads are upgraded as resources and budget allow. In terms of lifetime cost and long term pavement conditions, this will result in better system performance. Agencies that concentrate on restoring their bad roads often find that by the time they have repaired them all,

533-454: The beginning of the twentieth century. It consists of mineral aggregate bound together with bitumen (a substance also independently known as asphalt), laid in layers, and compacted. The process was refined and enhanced by Belgian-American inventor Edward De Smedt . Edgar Purnell Hooley further enhanced the process in the UK where the term tar macadam, shortened to tarmac was coined, after

574-406: The subsoil to see how much load it can withstand. The pavement and subbase thicknesses are designed to withstand the wheel loads. Sometimes, geogrids are used to reinforce the subbase and further strengthen the roads. Drainage, including ditches , storm drains and underdrains are used to remove water from the roadbed, preventing it from weakening the subbase and subsoil. Sealcoating asphalt

615-604: The Department of Transportation to incorporate crumb rubber into asphalt paving materials. Other recycled materials that are actively included in asphalt concrete mixes across the United States include steel slag, blast furnace slag, and cellulose fibers. Further research has been conducted to discover new forms of waste that may be recycled into asphalt mixes. A 2020 study conducted in Melbourne, Australia presented

656-496: The United States contained, on average, 21.1% RAP and 0.2% RAS. Recycled asphalt components may be reclaimed and transported to an asphalt plant for processing and use in new pavements, or the entire recycling process may be conducted in-place. While in-place recycling typically occurs on roadways and is specific to RAP, recycling in asphalt plants may utilize RAP, RAS, or both. In 2019, an estimated 97.0 million tons of RAP and 1.1 million tons of RAS were accepted by asphalt plants in

697-534: The United States. RAP is typically received by plants after being milled on-site, but pavements may also be ripped out in larger sections and crushed in the plant. RAP millings are typically stockpiled at plants before being incorporated into new asphalt mixes. Prior to mixing, stockpiled millings may be dried and any that have agglomerated in storage may have to be crushed. RAS may be received by asphalt plants as post-manufacturer waste directly from shingle factories, or they may be received as post-consumer waste at

738-416: The United States. Many roofing shingles also contain asphalt, and asphalt concrete mixes may contain reclaimed asphalt shingles (RAS). Research has demonstrated that RAP and RAS can replace the need for up to 100% of the virgin aggregate and asphalt binder in a mix, but this percentage is typically lower due to regulatory requirements and performance concerns. In 2019, new asphalt pavement mixtures produced in

779-441: The asphalt to oxidize, becoming stiffer and less resilient, leading to crack formation. Cold temperatures can cause cracks as the asphalt contracts. Cold asphalt is also less resilient and more vulnerable to cracking. Water trapped under the pavement softens the subbase and subgrade, making the road more vulnerable to traffic loads. Water under the road freezes and expands in cold weather, causing and enlarging cracks. In spring thaw,

820-508: The end of their service life. Processing of RAS includes grinding the shingles and sieving the grinds to remove oversized particles. The grinds may also be screened with a magnetic sieve to remove nails and other metal debris. The ground RAS is then dried, and the asphalt cement binder can be extracted. For further information on RAS processing, performance, and associated health and safety concerns, see Asphalt Shingles . In-place recycling methods allow roadways to be rehabilitated by reclaiming

861-691: The existing pavement, remixing, and repaving on-site. In-place recycling techniques include rubblizing , hot in-place recycling, cold in-place recycling, and full-depth reclamation . For further information on in-place methods, see Road Surface . During its service life, the asphalt cement binder, which makes up about 5–6% of a typical asphalt concrete mix, naturally hardens and becomes stiffer. This aging process primarily occurs due to oxidation, evaporation, exudation, and physical hardening. For this reason, asphalt mixes containing RAP and RAS are prone to exhibiting lower workability and increased susceptibility to fatigue cracking. These issues are avoidable if

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902-414: The friction course. In general, the viscosity of asphalt allows it to conveniently form a convex surface, and a central apex to streets and roads to drain water to the edges. This is not, however, in itself an advantage over concrete, which has various grades of viscosity and can be formed into a convex road surface. Rather, it is the economy of asphalt concrete that renders it more frequently used. Concrete

943-400: The ground thaws from the top down, so water is trapped between the pavement above and the still-frozen soil underneath. This layer of saturated soil provides little support for the road above, leading to the formation of potholes. This is more of a problem for silty or clay soils than sandy or gravelly soils. Some jurisdictions pass frost laws to reduce the allowable weight of trucks during

984-416: The lack of compaction in the trench, and also because of water intrusion through improperly sealed joints. Environmental factors include heat and cold, the presence of water in the subbase or subgrade soil underlying the pavement, and frost heaves. High temperatures soften the asphalt binder, allowing heavy tire loads to deform the pavement into ruts. Paradoxically, high heat and strong sunlight also cause

1025-498: The mix's rutting resistance while maintaining adequate fatigue cracking resistance. In mixes with higher recycled content, the addition of virgin binder becomes less effective, and rejuvenators may be used. Rejuvenators are additives that restore the physical and chemical properties of the aged binder. When conventional mixing methods are used in asphalt plants, the upper limit for RAP content before rejuvenators become necessary has been estimated at 50%. Research has demonstrated that

1066-424: The name of his company Tar Macadam (Purnell Hooley's Patent) Syndicate Limited derived from the combination of tar and Macadam gravel composite mixtures. The terms asphalt (or asphaltic ) concrete , bituminous asphalt concrete , and bituminous mixture are typically used only in engineering and construction documents, which define concrete as any composite material composed of mineral aggregate adhered with

1107-409: The number, width and length of cracks increases, more intensive repairs are needed. In order of generally increasing expense, these include thin asphalt overlays, multicourse overlays, grinding off the top course and overlaying, in-place recycling, or full-depth reconstruction of the roadway. It is far less expensive to keep a road in good condition than it is to repair it once it has deteriorated. This

1148-404: The pavement for controlling storm water. Different types of asphalt concrete have different performance characteristics in roads in terms of surface durability, tire wear, braking efficiency and roadway noise . In principle, the determination of appropriate asphalt performance characteristics must take into account the volume of traffic in each vehicle category, and the performance requirements of

1189-401: The performance aspects of RAP and RAS is to combine the recycled components with virgin aggregate and virgin asphalt binder. This approach can be effective when the recycled content in the mix is relatively low, and has a tendency to work more effectively with soft virgin binders. A 2020 study found that the addition of 5% RAS to a mix with a soft, low-grade virgin binder significantly increased

1230-468: The properties of the final product. Areas paved with asphalt concrete—especially airport aprons —have been called "the tarmac" at times, despite not being constructed using the tarmacadam process. A variety of specialty asphalt concrete mixtures have been developed to meet specific needs, such as stone-matrix asphalt , which is designed to ensure a strong wearing surface, or porous asphalt pavements, which are permeable and allow water to drain through

1271-422: The recycled components are apportioned correctly in the mix. Practicing proper storage and handling, such as by keeping RAP stockpiles out of damp areas or direct sunlight, is also important in avoiding quality issues. The binder aging process may also produce some beneficial attributes, such as by contributing to higher levels of rutting resistance in asphalts containing RAP and RAS. One approach to balancing

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1312-629: The rest of Duluth since 1905 by the Aerial Lift Bridge . Beginning in 2023, North Shore LS LLC (managed by Kathy Cargill, member of the Cargill family ) began purchasing and renovating properties located on Minnesota Point, owning twenty properties by March 2024. Cargill, in an interview with the Wall Street Journal stated that her intentions were to beautify and modernize the neighborhood, including building amenities such as

1353-446: The road over a longer period of time, increasing ruts, cracking, and corrugations in the asphalt pavement. Other causes of damage include heat damage from vehicle fires, or solvent action from chemical spills. The life of a road can be prolonged through good design, construction and maintenance practices. During design, engineers measure the traffic on a road, paying special attention to the number and types of trucks. They also evaluate

1394-421: The roads that were in good condition have deteriorated. Some agencies use a pavement management system to help prioritize maintenance and repairs. Asphalt concrete is a recyclable material that can be reclaimed and reused both on-site and in asphalt plants . The most common recycled component in asphalt concrete is reclaimed asphalt pavement (RAP). RAP is recycled at a greater rate than any other material in

1435-398: The selection of the type of surface paving, arose in the early 1970s. With regard to structural performance, the asphalt behaviour depends on a variety of factors including the material, loading and environmental condition. Furthermore, the performance of pavement varies over time. Therefore, the long-term behaviour of asphalt pavement is different from its short-term performance. The LTPP

1476-541: The southeast end of the runway along the edge of Park Point, in order to angle the runway into the bay rather than toward the forest. The old Runway 32 had a displaced threshold 658 ft past the beginning of the hard surface, leaving 2,392 ft for landing. For the 12-month period ending April 30, 2018, the airport had 13,900 aircraft operations, an average of 38 per day: 94% general aviation and 6% air taxi . In 2018, there were 24 aircraft based at this airport: 21 single-engine and 3 multi-engine. Sky Harbor Airport

1517-404: The spring thaw season and protect their roads. The damage a vehicle causes is roughly proportional to the axle load raised to the fourth power, so doubling the weight an axle carries actually causes 16 times as much damage. Wheels cause the road to flex slightly, resulting in fatigue cracking, which often leads to crocodile cracking. Vehicle speed also plays a role. Slowly moving vehicles stress

1558-582: The two ports, Duluth (Minnesota) and Superior (Wisconsin), became fierce economic competitors for shipping traffic off of Lake Superior. As commercial traffic on the lake increased with the completion of the Sault Ste Marie canal connecting Lake Superior to Lake Michigan, Congress appropriated the funds to build a lighthouse on the narrow opening in Minnesota Point, known as Superior Entry. The Minnesota Point Light , built between 1855 and 1858,

1599-530: The use of rejuvenators at optimal doses can allow for mixes with 100% recycled components to meet the performance requirements of conventional asphalt concrete. Beyond RAP and RAS, a range of waste materials can be re-used in place of virgin aggregate, or as rejuvenators. Crumb rubber, generated from recycled tires, has been demonstrated to improve the fatigue resistance and flexural strength of asphalt mixes that contain RAP. In California, legislative mandates require

1640-633: Was founded in 1946 by Jack Brockway and William Neukom. Asphalt concrete Asphalt concrete (commonly called asphalt , blacktop , or pavement in North America, and tarmac or bitumen macadam in the United Kingdom and the Republic of Ireland) is a composite material commonly used to surface roads , parking lots , airports , and the core of embankment dams . Asphalt mixtures have been used in pavement construction since

1681-548: Was the first to use RH Barret's Fifth Order Fresnel lamp and Barret became the station's first lighthouse keeper, succeeded in 1861 by Samuel Stewart Palmer. Affectionately known as "The Old Standby", this lighthouse is now an abandoned ruin listed on the National Register of Historic Places . Since the digging of the Duluth Ship Canal in 1870–1871, Minnesota Point is technically an island, connected to

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