1.
Concrete
–
Concrete is a composite material composed of coarse aggregate bonded together with a fluid cement that hardens over time. Most concretes used are lime-based concretes such as Portland cement concrete or concretes made with other hydraulic cements, when aggregate is mixed together with dry Portland cement and water, the mixture forms a fluid slurry that is easily poured and molded into shape. The cement reacts chemically with the water and other ingredients to form a matrix that binds the materials together into a durable stone-like material that has many uses. Often, additives are included in the mixture to improve the properties of the wet mix or the finished material. Most concrete is poured with reinforcing materials embedded to provide tensile strength, famous concrete structures include the Hoover Dam, the Panama Canal, and the Roman Pantheon. The earliest large-scale users of technology were the ancient Romans. The Colosseum in Rome was built largely of concrete, and the dome of the Pantheon is the worlds largest unreinforced concrete dome. Today, large concrete structures are made with reinforced concrete. After the Roman Empire collapsed, use of concrete became rare until the technology was redeveloped in the mid-18th century, today, concrete is the most widely used man-made material. The word concrete comes from the Latin word concretus, the passive participle of concrescere, from con-. Perhaps the earliest known occurrence of cement was twelve years ago. A deposit of cement was formed after an occurrence of oil shale located adjacent to a bed of limestone burned due to natural causes and these ancient deposits were investigated in the 1960s and 1970s. On a human timescale, small usages of concrete go back for thousands of years and they discovered the advantages of hydraulic lime, with some self-cementing properties, by 700 BC. They built kilns to supply mortar for the construction of houses, concrete floors. The cisterns were kept secret and were one of the reasons the Nabataea were able to thrive in the desert, some of these structures survive to this day. In the Ancient Egyptian and later Roman eras, it was re-discovered that adding volcanic ash to the mix allowed it to set underwater, similarly, the Romans knew that adding horse hair made concrete less liable to crack while it hardened, and adding blood made it more frost-resistant. Crystallization of strätlingite and the introduction of pyroclastic clays creates further fracture resistance, german archaeologist Heinrich Schliemann found concrete floors, which were made of lime and pebbles, in the royal palace of Tiryns, Greece, which dates roughly to 1400–1200 BC. Lime mortars were used in Greece, Crete, and Cyprus in 800 BC, the Assyrian Jerwan Aqueduct made use of waterproof concrete
2.
Asphalt
–
Asphalt, also known as bitumen is a sticky, black and highly viscous liquid or semi-solid form of petroleum. It may be found in deposits or may be a refined product. Until the 20th century, the term asphaltum was also used, the word is derived from the Ancient Greek ἄσφαλτος ásphaltos. The primary use of asphalt/bitumen is in construction, where it is used as the glue or binder mixed with aggregate particles to create asphalt concrete. Its other main uses are for bituminous waterproofing products, including production of roofing felt, the terms asphalt and bitumen are often used interchangeably to mean both natural and manufactured forms of the substance. In American English, asphalt is the carefully refined residue from the process of selected crude oils. Outside the United States, the product is often called bitumen, geologists often prefer the term bitumen. Common usage often refers to forms of asphalt/bitumen as tar. Naturally occurring asphalt/bitumen is sometimes specified by the crude bitumen. Its viscosity is similar to that of cold molasses while the material obtained from the distillation of crude oil boiling at 525 °C is sometimes referred to as refined bitumen. The Canadian province of Alberta has most of the reserves of natural bitumen, covering 142,000 square kilometres. Additionally, most natural bitumens contain organosulfur compounds, resulting in a sulfur content of up to 4%. Nickel and vanadium are found in the <10 ppm level, as is typical of some petroleum, the substance is soluble in carbon disulfide. It is commonly modelled as a colloid, with asphaltenes as the dispersed phase, and it is almost impossible to separate and identify all the different molecules of asphalt, because the number of molecules with different chemical structure is extremely large. Asphalt/bitumen can sometimes be confused with tar, which is a visually similar black. During the early and mid-20th century when town gas was produced, coal tar was a readily available byproduct, the addition of tar to macadam roads led to the word tarmac, which is now used in common parlance to refer to road-making materials. However, since the 1970s, when natural gas succeeded town gas, other examples of this confusion include the La Brea Tar Pits and the Canadian oil sands, both of which actually contain natural bitumen rather than tar. Pitch is another term used at times to refer to asphalt/bitumen
3.
Road surface
–
Road surface or pavement is the durable surface material laid down on an area intended to sustain vehicular or foot traffic, such as a road or walkway. In the past, gravel road surfaces, cobblestone and granite setts were extensively used, Road surfaces are frequently marked to guide traffic. Today, permeable paving methods are beginning to be used for low-impact roadways and walkways, asphalt, sometimes called flexible pavement due to the nature in which it distributes loads, has been widely used since the 1920s. The viscous nature of the bitumen binder allows asphalt concrete to sustain significant plastic deformation, most asphalt surfaces are laid on a gravel base, which is generally at least as thick as the asphalt layer, although some full depth asphalt surfaces are laid directly on the native subgrade. In areas with soft or expansive subgrades such as clay or peat. Depending on the temperature at which it is applied, asphalt is categorized as hot mix, warm mix, hot mix asphalt is applied at temperatures over 300 °F with a free floating screed. Warm mix asphalt is applied at temperatures of 200–250 °F, resulting in reduced energy usage, cold mix asphalt is often used on lower volume rural roads, where hot mix asphalt would cool too much on the long trip from the asphalt plant to the construction site. An asphalt concrete surface will generally be constructed for primary highways having an average annual daily traffic load greater than 1200 vehicles per day. Advantages of asphalt roadways include relatively low noise, relatively low cost compared with other paving methods, in the mid-1960s, rubberized asphalt was used for the first time, mixing crumb rubber from used tires with asphalt. Also, application of rubberized asphalt is more temperature-sensitive, and in many locations can only be applied at times of the year. Study results of the long-term acoustic benefits of rubberized asphalt are inconclusive, compared to traditional passive attenuating measures, rubberized asphalt provides shorter-lasting and lesser acoustic benefits at typically much greater expense. Concrete surfaces are created using a mix of Portland cement, coarse aggregate, sand. In many cases there will also be Portland cement substitutes added and this can reduce the cost of the concrete and improve its physical properties. The water allows the mix to combine molecularly in a reaction called hydration. Concrete surfaces have been refined into three types, jointed plain, jointed reinforced and continuously reinforced. The one item that each type is the jointing system used to control crack development. Jointed plain concrete pavements contain enough joints to control the location of all the expected shrinkage cracks, the concrete cracks at the joints and not elsewhere in the slabs. Jointed plain pavements do not contain any steel reinforcement, however, there may be smooth steel bars at transverse joints and deformed steel bars at longitudinal joints
4.
Road
–
Roads consist of one or two roadways, each with one or more lanes and any associated sidewalks and road verges. Roads that are available for use by the public may be referred to as parkways, avenues, freeways, interstates, highways, or primary, secondary, and tertiary local roads. In urban areas roads may diverge through a city or village and be named as streets, serving a function as urban space easement. Modern roads are normally smoothed, paved, or otherwise prepared to allow easy travel, historically many roads were simply recognizable routes without any formal construction or maintenance. In the United Kingdom there is ambiguity between the terms highway and road. The Highway code details rules for road users and this includes footpaths, bridleways and cycle tracks, and also road and driveways on private land and many car parks. Vehicle Excise Duty, a use tax, is payable on some vehicles used on the public road. The definition of a road depends on the definition of a highway, in the United States, laws distinguish between public roads, which are open to public use, and private roads, which are privately controlled. The assertion that the first pathways were the trails made by animals has not been universally accepted, others believe that some roads originated from following animal trails. The Icknield Way is given as an example of type of road origination. By about 10,000 BC, rough roads/pathways were used by human travelers, the worlds oldest known paved road was constructed in Egypt some time between 2600 and 2200 BC. Stone-paved streets are found in the city of Ur in the Middle East dating back to 4000 BC, corduroy roads are found dating to 4000 BC in Glastonbury, England. The Sweet Track, a timber causeway in England, is one of the oldest engineered roads discovered. Built in winter 3807 BC or spring 3806 BC, tree-ring dating enabled very precise dating and it was claimed to be the oldest road in the world until the 2009 discovery of a 6, 000-year-old trackway in Plumstead, London. Brick-paved streets were used in India as early as 3000 BC, in 500 BC, Darius I the Great started an extensive road system for Persia, including the Royal Road, which was one of the finest highways of its time. The road remained in use after Roman times, a hybrid of road transport and ship transport beginning in about 1740 is the horse-drawn boat in which the horse follows a cleared path along the river bank. From about 312 BC, the Roman Empire built straight strong stone Roman roads throughout Europe and North Africa, at its peak the Roman Empire was connected by 29 major roads moving out from Rome and covering 78,000 kilometers or 52,964 Roman miles of paved roads. In the 8th century AD, many roads were built throughout the Arab Empire, the most sophisticated roads were those in Baghdad, which were paved with tar
5.
Interstate 10 in California
–
In the greater Los Angeles area, it is known as the Santa Monica Freeway and the San Bernardino Freeway, linked by a short concurrency on Interstate 5 at the East Los Angeles Interchange. Interstate 10 also has designated as either the Rosa Parks Freeway or the Redlands Freeway. The California Streets and Highways Code defines Route 10 from Route 1 in Santa Monica to Route 5 near Seventh Street in Los Angeles. Route 101 near Mission Road in Los Angeles to the Arizona state line at the Colorado River via the vicinity of Monterey Park, Pomona, Colton, Indio, and Chiriaco Summit and via Blythe. This short section of Route 10 between Route 5 and Route 101, which was defined as Route 110 until 1968, is signed overhead for I-10 eastbound. This I-5/I-10 cosigning is consistent with the Federal Highway Administrations Interstate Highway route logs that such an overlap exists for the segment of I-10 in California, I-10 is part of the California Freeway and Expressway System and is eligible for the State Scenic Highway System. However, it is not actually a scenic highway as designated by Caltrans, the Santa Monica Freeway is Route 10 from Route 1 to Route 5, as named by the State Highway Commission on April 25,1957. The section between the Harbor and San Diego freeways is also signed as the Rosa Parks Freeway, after the African American civil rights activist, the I-10 freeway is signed as the Christopher Columbus Transcontinental Highway in Santa Monica. Interstate 10 begins in the city of Santa Monica when State Route 1 turns into a freeway, SR1 exits onto Lincoln Boulevard and heads south while I-10 continues east. Soon after it enters the city of Los Angeles, I-10 has a interchange with Interstate 405. On the western edge of downtown, I-10 has an interchange with Interstate 110 to the south, I-10 then travels along the southern edge of downtown to the East Los Angeles Interchange. At the East Los Angeles Interchange, State Route 60 diverges east towards Riverside, I-10 then turns north, running concurrently with Interstate 5 for a few miles. Then, Interstate 10 heads east and merges with the traffic from the spur to US101 onto the San Bernardino Freeway, the freeway is 14 lanes wide from the Harbor Freeway interchange to the Arlington Avenue off-ramp. Most of these lanes are full at peak travel times, the remainder of the freeway varies between eight and 10 lanes in width. The whole freeway opened in 1965, with a dedication held in 1966. All three freeway-to-freeway interchanges along its length are notorious for their congestion, and are ranked among the top 10 most congested spots in the United States. Due to the traffic volume, car accidents are so common that Caltrans has constructed special Accident Investigation Sites separated from the freeway by fences. These enable the California Highway Patrol to quickly clear accidents from the traffic lanes
6.
Portland cement
–
Portland cement is the most common type of cement in general use around the world, used as a basic ingredient of concrete, mortar, stucco, and most non-speciality grout. It was developed from other types of lime in England in the mid 19th century. It is a fine powder produced by heating materials in a kiln to form what is called clinker, grinding the clinker, and adding small amounts of other materials. Several types of Portland cement are available, with the most common being called ordinary Portland cement which is grey in color, Portland cement is caustic, so it can cause chemical burns. The powder can cause irritation or, with exposure, lung cancer and can contain some hazardous components such as crystalline silica. Concrete produced from Portland cement is one of the most versatile construction materials available in the world, Portland cement was developed from natural cements made in Britain beginning in the middle of the 18th century. Its name is derived from its similarity to Portland stone, a type of building stone quarried on the Isle of Portland in Dorset, England. In the late 18th century, Roman cement was developed and patented in 1796 by James Parker, Roman cement quickly became popular, in 1811 James Frost produced a cement he called British cement. James Frost is reported to have erected a manufactory for making of an artificial cement in 1826, in 1843, Aspdins son William improved their cement, which was initially called Patent Portland cement, although he had no patent. In 1818, French engineer Louis Vicat invented a hydraulic lime considered the principal forerunner of Portland cement. Edgar Dobbs of Southwark patented a cement of this kind in 1811, Portland cement was used by Joseph Aspdin in his cement patent in 1824 because of the cements resemblance to Portland stone. The name Portland cement is also recorded in a directory published in 1823 being associated with a William Lockwood, a Dave Stewart, however, Aspdins cement was nothing like modern Portland cement but was a first step in the development of modern Portland cement, called a proto-Portland cement. William Aspdin had left his fathers company and in his cement manufacturing apparently accidentally produced calcium silicates in the 1840s, in 1848, William Aspdin further improved his cement, in 1853, he moved to Germany, where he was involved in cement making. William Aspdin made what could be called meso-Portland cement, isaac Charles Johnson further refined the production of meso-Portland cement and claimed to be the real father of Portland cement. John Grant of the Metropolitan Board of Works in 1859 set out requirements for cement to be used in the London sewer project and this became a specification for Portland cement. The Hoffman endless kiln which gave control over combustion was tested in 1860. This cement was made at the Portland Cementfabrik Stern at Stettin and it is thought that the first modern Portland cement was made there. The Association of German Cement Manufacturers issued a standard on Portland cement in 1878, by the early 20th century American-made Portland cement had displaced most of the imported Portland cement
7.
Diamond
–
Diamond is a metastable allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the rate from diamond to graphite is negligible at standard conditions. Diamond is renowned as a material with superlative physical qualities, most of which originate from the covalent bonding between its atoms. In particular, diamond has the highest hardness and thermal conductivity of any bulk material and those properties determine the major industrial application of diamond in cutting and polishing tools and the scientific applications in diamond knives and diamond anvil cells. Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as boron, small amounts of defects or impurities color diamond blue, yellow, brown, green, purple, pink, orange or red. Diamond also has relatively high optical dispersion, most natural diamonds are formed at high temperature and pressure at depths of 140 to 190 kilometers in the Earths mantle. Carbon-containing minerals provide the source, and the growth occurs over periods from 1 billion to 3.3 billion years. Diamonds are brought close to the Earths surface through deep volcanic eruptions by magma, Diamonds can also be produced synthetically in a HPHT method which approximately simulates the conditions in the Earths mantle. An alternative, and completely different growth technique is chemical vapor deposition, several non-diamond materials, which include cubic zirconia and silicon carbide and are often called diamond simulants, resemble diamond in appearance and many properties. Special gemological techniques have developed to distinguish natural diamonds, synthetic diamonds. The word is from the ancient Greek ἀδάμας – adámas unbreakable, the name diamond is derived from the ancient Greek αδάμας, proper, unalterable, unbreakable, untamed, from ἀ-, un- + δαμάω, I overpower, I tame. Diamonds have been known in India for at least 3,000 years, Diamonds have been treasured as gemstones since their use as religious icons in ancient India. Their usage in engraving tools also dates to early human history, later in 1797, the English chemist Smithson Tennant repeated and expanded that experiment. By demonstrating that burning diamond and graphite releases the same amount of gas, the most familiar uses of diamonds today are as gemstones used for adornment, a use which dates back into antiquity, and as industrial abrasives for cutting hard materials. The dispersion of light into spectral colors is the primary gemological characteristic of gem diamonds. In the 20th century, experts in gemology developed methods of grading diamonds, four characteristics, known informally as the four Cs, are now commonly used as the basic descriptors of diamonds, these are carat, cut, color, and clarity. A large, flawless diamond is known as a paragon and these conditions are met in two places on Earth, in the lithospheric mantle below relatively stable continental plates, and at the site of a meteorite strike. The conditions for diamond formation to happen in the mantle occur at considerable depth corresponding to the requirements of temperature and pressure
8.
Construction aggregate
–
Aggregates are the most mined materials in the world. Aggregates are a component of composite materials such as concrete and asphalt concrete, aggregates are also used as base material under foundations, roads, and railroads. Preferred bitumenous aggregate sizes for road construction are given in EN13043 as d/D, the same classification sizing is used for larger armour stone sizes in EN13383, EN12620 for concrete aggregate, EN13242 for base layers of road construction and EN13450 for railway ballast. These products include specific types of coarse and fine aggregate designed for such uses as additives to asphalt and concrete mixes, state transportation departments further refine aggregate material specifications in order to tailor aggregate use to the needs and available supply in their particular locations. In addition, there are materials that are used as specialty lightweight aggregates, clay, pumice, perlite. People have used sand and stone for foundations for thousands of years, significant refinement of the production and use of aggregate occurred during the Roman Empire, which used aggregate to build its vast network of roads and aqueducts. The invention of concrete, which was essential to architecture utilizing arches, created an immediate, vitruvius writes in De architectura, Economy denotes the proper management of materials and of site, as well as a thrifty balancing of cost and common sense in the construction of works. This will be observed if, in the first place, the architect does not demand things which cannot be found or made ready without great expense, for example, it is not everywhere that there is plenty of pit-sand, rubble, fir, clear fir, and marble. Where there is no pit sand, we must use the kinds washed up by rivers or by the sea. the advent of modern blasting methods enabled the development of quarries, which are now used throughout the world, wherever competent bedrock deposits of aggregate quality exist. In many places, good limestone, granite, marble or other quality stone bedrock deposits do not exist, in these areas, natural sand and gravel are mined for use as aggregate. Where neither stone, nor sand and gravel, are available, construction demand is satisfied by shipping in aggregate by rail. Additionally, demand for aggregates can be satisfied through the use of slag. However, the available tonnages and lesser quality of these materials prevent them from being a replacement for mined aggregates on a large scale. Large stone quarry and sand and gravel operations exist near virtually all population centers, limestone and granite are also produced in large amounts as dimension stone. The great majority of crushed stone is moved by truck from the quarry/plant to the first point of sale or use. According to the USGS,2006 U. S. sand and gravel production was 1.32 billion tonnes valued at $8.54 billion, the great majority of this was again moved by truck, instead of by electric train. Currently, total U. S. aggregate demand by final market sector was 30%–35% for non-residential building, 25% for highways, the largest-volume of recycled material used as construction aggregate is blast furnace and steel furnace slag. Blast furnace slag is either air-cooled or granulated, if the granulated blast furnace slag accesses free lime during hydration, it develops strong hydraulic cementitious properties and can partly substitute for portland cement in concrete
9.
Pavement milling
–
Pavement milling is the process of removing at least part of the surface of a paved area such as a road, bridge, or parking lot. Milling removes anywhere from just enough thickness to level and smooth the surface to a full depth removal, there are a number of different reasons for milling a paved area instead of simply repaving over the existing surface. Recycling of the surface is one of the main reasons for milling a road surface. Milling is widely used for pavement recycling today, where the pavement is removed and this reduces the impact that resurfacing has on the environment. Milling can also remove distresses from the surface, providing a driving experience and/or longer roadway life. This can be done to control heights and clearances of other structures such as, curb reveals, manhole and catch basin heights, shoulder and guardrail heights. It can also be done to change the slope or camber of the road or for grade adjustments which can help with drainage, specialty milling can be used to form rumble strips which are often used along highways. Using milling instead of other methods, such as rolling them in, another example is to modify the roto-milling head to create slots in concrete slabs for the dowel bar retrofit process. The typical process is to saw cut and jackhammer out the slots for the dowels, following dowel placement, the slots are then typically backfilled with a non-shrink concrete mixture, and the pavement is diamond-ground to restore smoothness. This special milling process shortens the time to create slots from the method which is labor-intensive. The Asphalt Recycling and Reclaiming Association has defined five classes of cold planing that the Federal Highway Administration has recognized and these machines use a large rotating drum to remove and grind the road surface. The drum consists of scrolls of tool holders, the scrolls are positioned around the drum such that the ground pavement is moved toward the center and can be loaded onto the machines conveyor belt. The tool holders can wear out over time and can be broken while milling if highway structures like manholes are encountered while milling, the tool holders on the drum hold carbide cutters. The cutters can be removed and replaced as they wear out, the amount of wear varies with the type and consistency of the material being milled, intervals can range from a few hours to several days. The drum is enclosed in a housing/scrapper that is used to contain the material to be collected and deposited on the conveyor. The spacing of the tool spirals around the drum affect the end surface of the road, the majority of milling machines use an up-cut setup which means that the drum rotates in the direction opposite that of the drive wheel or tracks. The speed of the rotating drum should be slower than the speed of the machine for a suitable finished surface. Modern machines generally use a front loading conveyor system that have the advantage of picking up any material that falls off the conveyor as milling progresses, water is generally applied to the drum as it spins, because of the heat generated during the milling process
10.
Hydraulics
–
Hydraulics is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids or fluids. At a very basic level, hydraulics is the version of pneumatics. Fluid mechanics provides the foundation for hydraulics, which focuses on the applied engineering using the properties of fluids. In fluid power, hydraulics are used for the generation, control, hydraulic topics range through some parts of science and most of engineering modules, and cover concepts such as pipe flow, dam design, fluidics and fluid control circuitry, pumps. The principles of hydraulics are in use naturally in the body within the heart. Free surface hydraulics is the branch of hydraulics dealing with surface flow, such as occurring in rivers, canals, lakes, estuaries. Its sub-field open channel flow studies the flow in open channels, the word hydraulics originates from the Greek word ὑδραυλικός which in turn originates from ὕδωρ and αὐλός. Early uses of water power date back to Mesopotamia and ancient Egypt, other early examples of water power include the Qanat system in ancient Persia and the Turpan water system in ancient Central Asia. The Greeks constructed sophisticated water and hydraulic power systems, an example is the construction by Eupalinos, under a public contract, of a watering channel for Samos, the Tunnel of Eupalinos. An early example of the usage of hydraulic wheel, probably the earliest in Europe, is the Perachora wheel, notable is the construction of the first hydraulic automata by Ctesibius and Hero of Alexandria. Hero describes a number of working machines using hydraulic power, such as the force pump, in ancient China there was Sunshu Ao, Ximen Bao, Du Shi, Zhang Heng, and Ma Jun, while medieval China had Su Song and Shen Kuo. Du Shi employed a waterwheel to power the bellows of a blast furnace producing cast iron, Zhang Heng was the first to employ hydraulics to provide motive power in rotating an armillary sphere for astronomical observation. In ancient Sri Lanka, hydraulics were used in the ancient kingdoms of Anuradhapura. The discovery of the principle of the tower, or valve pit. By the first century AD, several irrigation works had been completed. The coral on the rock at the site includes cisterns for collecting water. They were among the first to use of the siphon to carry water across valleys. They used lead widely in plumbing systems for domestic and public supply, hydraulic mining was used in the gold-fields of northern Spain, which was conquered by Augustus in 25 BC
11.
Dowel bar retrofit
–
A dowel bar retrofit is a method of reinforcing cracks in highway pavement by inserting steel dowel bars in slots cut across the cracks. It is a technique several states have used to address faulting in older jointed plain concrete pavements. The typical approach is to saw cut and jackhammer out the slots for the dowels, following dowel placement the slots are then typically backfilled with a non-shrink concrete mixture and the pavement is diamond-ground to restore smoothness. As a vehicle travels on jointed concrete roads the weight of the passes from one concrete panel to the next. As the vehicle traverses the joints its weight is placed on the edge of the panel and this can cause cracks as pavement shears off the edge of the panel. On older highways built in the early-to-mid 20th century, dowel bars were placed across the joints to help transfer the load from one panel to the next and this was discontinued because the dowel bars tended to corrode and required frequent replacement. Stainless steel dowel bars are more resistant to corrosion, but stainless steel is expensive compared to other materials. Over time the joints and roadbed tended to break down under stress, resulting in cracks and displacement of the panels. Most highways in the United States built as part of the Interstate Highway System from the 1950s to the 1980s relied solely upon aggregate interlock, in contemporary highway construction since the mid-1990s, dowel bars are once again placed across joints and at intervals along the pavement. Today, dowel bars are coated with epoxy to prevent the problems seen in earlier installations. Many states are retrofitting older highways with epoxy-coated dowel bars, the retrofit begins with cutting of six slots across all transverse joints or cracks. The slots are cut with ganged diamond saws that make six cuts in each wheel path, the concrete between the saw cuts is then removed with lightweight jackhammers. The epoxy-coated dowel bars are placed in the slots, then the slots are filled with grout, the final step is to diamond-grind the joint to remove both excess grout and any displacement of the panels. The final step often involves diamond-grinding of the road surface to remove any bumps or dips. Without the dowel bar retrofit this grinding would have to be repeated every six to eight years, dowel Bar Retrofit has been proven to outlast Asphalt Overlay by at least ten years, and significantly improves ride quality. For dowel bar retrofit, dowels, bond breaker, expansion caps, dowel bar support chairs, foam core insert, caulking filler, non-shrink concrete backfill material, the dowels need to be smooth, round, epoxy and made of bond breaker coated steel conforming to requirements. The bond breaker is to be applied on all surfaces of the dowel bar, the expansion caps belong at each end of the dowel bar and the dowel bar support chairs are used to firmly hold the dowels centered in the slots during backfill operations. The foam core insert is used to re-establish the joint or crack, the caulking filler is used to prevent backfill material from flowing into the joint or crack
