Remember, the compaction rate, as a general rule, is about 6 mm (1/4″) per 25 mm (1″) of screed laid thickness when a vibratory screed is used and about 5 mm (1/5″) per 25 mm (1″) when a tamping and vibrating screed is used. How is asphalt compaction measured? The most common method is a Nuclear Density Gauge.
How hard is it to compaction asphalt?
Typically, asphalt comes out of the plant at about 300° F. At that temperature, it is relatively soft and is readily compacted. As it cools, it firms up and compaction becomes increasingly difficult. "The three most important factors when it comes to compaction are temperature, temperature, temperature.
What temperature does asphalt need to be compacted?
Asphalt concrete mixtures cool quickly so it’s important to compact while the mix is hot. Typically, asphalt comes out of the plant at about 300° F. At that temperature, it is relatively soft and is readily compacted. As it cools, it firms up and compaction becomes increasingly difficult.
Does wind velocity affect the cooling rate of asphalt concrete?
Wind velocity, however, can have a significant effect of the rate of cooling as well,” Scherocman says. Asphalt concrete mixtures cool quickly so it’s important to compact while the mix is hot. Typically, asphalt comes out of the plant at about 300° F. At that temperature, it is relatively soft and is readily compacted.
What factors affect the density of an asphalt paver mat?
There are five factors that affect finished density of the asphalt mat: temperature of the mix itself, mat thickness, base temperature, environmental conditions (air temperature), and wind. “The two most important factors are the temperature of the mix as it passes out from under the screed of the paver and the thickness of the layer.
What is the compaction of asphalt?
Compaction of asphalt mixes is a complex interaction between the workability of an asphalt mix and compactive effort. The most important factor in workability is the temperature of the asphalt mix during the compaction process. Asphalt temperature is influenced by placement temperature and rate of cooling.
What is the compaction percentage of asphalt?
What is the recommended air void content for compaction of asphalt pavements? Efforts should be made to control compacted air voids between 7% and 3%. At 8% or higher, interconnected voids which allow air and moisture to permeate the pavement, reducing its durability.
How much does loose asphalt compact?
Remember, the compaction rate, as a general rule, is about 6 mm (1/4") per 25 mm (1") of screed laid thickness when a vibratory screed is used and about 5 mm (1/5") per 25 mm (1") when a tamping and vibrating screed is used.
When rolling asphalt for compaction little or no compaction will occur once the asphalt has dropped below what temperature?
The train starts with a double drum vibratory roller operating close behind the paver to obtain the initial compactive effort while the mix is still hot. A rule of thumb is this “breakdown” rolling should be completed before the surface temperature of the mix falls below 240o F.
How do you calculate asphalt compaction?
Calculate the quantity of Asphalt= ( Density* Volume)/1000. Use the Compaction Factor for AWC (1.28% – 1.30% in Asphalt) and for ABC (1.23% – 1.26% in Asphalt) How to Measure Asphalt Quantity for Road. Total Weight of Asphalt with Compaction Factor = Quantity of AWC x Compaction Factor.
How do you measure asphalt compaction?
The most common method is a Nuclear Density Gauge. The gauge measures compaction as the pavement is placed. Therefore, a technician can tell the roller operator if additional compaction is needed. Once the pavement is placed, core samples with laboratory analysis can also be performed to confirm the compaction levels.
Can you compact asphalt too much?
If you don't compact the asphalt properly, it can start to break up and crack. But if you compress it too much, it can become brittle and chip away.
What is the maximum speed of the roller in compaction of asphalt pavement?
4 mphFor a vibratory roller capable of applying compactive effort at a rate of 3,600 vpm, the roller can be operated up to 4 mph. For a pneumatic-tire roller, the maximum speed should also be 4 mph. Rollers can move faster or slower than the recommended speed, but compaction varies directly with roller speed.
What is the density of compacted asphalt?
approximately 145 pounds per cubic footThe density of the compacted mix is its unit weight, or the weight of a specific volume of mix. For compacted HMA, this is approximately 145 pounds per cubic foot. Density is particularly important because high density of the finished pavement is essential for long term pavement performance.
What temperature do you roll asphalt?
Ideally you want to install asphalt when both ground and air temperature are anywhere between 50 and 90 degrees. Anything below 50 or above 90 can cause a poor pour that will give you issues down the road.
What is the proper way to roll asphalt?
11:4625:09HMA Paving Operations Video 4 – Rolling Operations - YouTubeYouTubeStart of suggested clipEnd of suggested clipIt's best to roll the lower edge.MoreIt's best to roll the lower edge.
What temperature does asphalt compact?
During initial application, the asphalt should still be at least 220 to 290-degrees Fahrenheit. If the asphalt dips below approximately 185-degrees Fahrenheit before compaction is complete, its consistency stiffens up too much to finish the job properly.
What is the density of compacted asphalt?
approximately 145 pounds per cubic footThe density of the compacted mix is its unit weight, or the weight of a specific volume of mix. For compacted HMA, this is approximately 145 pounds per cubic foot. Density is particularly important because high density of the finished pavement is essential for long term pavement performance.
How do you measure density of asphalt?
0:142:35ARDOT 461 - Nuclear Density Gauge - Asphalt Field Testing - YouTubeYouTubeStart of suggested clipEnd of suggested clipUse the scraper plate or other tool to distribute the sand into the pores and scrape off any excess.MoreUse the scraper plate or other tool to distribute the sand into the pores and scrape off any excess. So that the gauge will sit directly on the asphalt.
How do you compact hot mix asphalt?
In order to compact a HMA mix that is stiff, it is necessary to roll it as close behind the paver as possible. In order to compact a HMA mix that is tender, it is also necessary to roll it as close behind the paver as possible in order to take advantage of the upper temperature zone in the mix.
What is the density of asphalt wearing course?
Standard density for asphalt is 145 lb/ft3 (2322 kg/m3). Multiply the volume by the density (in the same units) to get the weight.
What is Compaction?
When it comes to asphalt installation, compaction is unquestionably the essential aspect. Compacting correctly allows asphalt to reach the required density and strength and helps prevent deterioration that considerably reduces pavement lifespan.
The Process of Compaction
There are many different ways to compact asphalt, but the most common is by roller. The procedure usually starts with placing a layer of hot mix asphalt (HMA) followed by a layer of coarse aggregate. These two layers are rolled together using a vibrating plate compactor or pneumatic tire roller.
Why Is Compaction Important?
Compaction is essential for two reasons: first, it helps to ensure a stable foundation for the pavement; second, it increases the strength and durability of the pavement. Compaction creates a solid surface that can withstand repeated use without becoming damaged when done correctly.
Problems Caused by Improper Compaction
If the asphalt is not compacted correctly, it can lead to several problems, including:
Get Professional Help
If you are big on saving time and don’t want to worry about the potential challenges of asphalt compaction, it is best to leave it to the professionals. Get in touch with us at Laurel Asphalt serving Johnstown.
What temperature does asphalt come out of the plant?
Monitoring mat temperature - Typically, asphalt comes out of the plant at about 300° F. At that temperature, it is relatively viscous and liquid and is readily compacted. As it cools, it firms up and compaction becomes increasingly difficult. At about 100° to 150° F, it has cooled enough that the aggregates no longer move. "A good operator understands the temperature envelope in which he has to work," says Monical.
What happens if a paver goes too fast?
In addition, if the paver is going too fast, it may run out of material and the operator will have to stop and wait. "When that happens, the paver screed settles and makes a dip," says Monical. "A good paving crew operates at a reasonable speed so the roller operator can keep pace, and the paver never has to stop.
What is the difference between static and vibratory compaction?
Determining when to use vibratory and static modes - Vibratory compaction creates shock waves that compact from the bottom up, while static compaction works from the top down. "For most jobs, you will use a combination of compaction modes, starting with vibratory compaction and finishing with static," Nittinger comments. "We recommend that you roll in vibratory mode out of the gate. With vibration, you're getting the desired density, and with static you're finalizing the compaction."
What are the influences of roller speed on mat quality?
Some of the topics training sessions focus upon include: Maintaining proper speed - Roller speed has one of the greatest influences on mat quality. Driving too slow can over compact the surface; driving too fast can leave gaps and compromise safety if the operator gets too close to the paver.
What is the density of a paver?
For one, there is a certain amount of pre-compaction generated by the paver. These density levels should be in the mid 70s to low 80s. "If the paver is going too fast, density may only be in the mid 60s," says Tomlinson. "Also, if the compactor operator has to speed up to keep pace with the paver, that changes the impact spacing. Either scenario is asking a lot of the compactor operator. The paver will either have to slow down, or you will have to add additional compactors to maintain a quality mat."
Why do pavers need to communicate?
The paver operator and compactor operator need to communicate to ensure both are moving at a pace that provides for optimum density and smoothness. Yet, paving crews are often paid based on how much they lay, says Tomlinson. That means they may be tempted to speed through the process, which can create a couple of problems.
What makes a good paving job?
A good paving job will have a smooth, dense appearance that looks flat and tight, without any gaps between the aggregates at the surface. Yet, that appearance doesn't just happen. There are a lot of factors that affect mat quality.
