3. Decreased viscosity of the asphalt binder in the produced hot mix asphalt A decrease in the asphalt viscosity from that expected may lead to a mixture which exhibits tenderness during compaction. A reduction in viscosity can be caused by increased temperatures, less mix aging, contamination, or inconsistent grade of supplied binder.

cause binder hardening, mix tenderness and binder fuming. • Pavement temperature : The colder the pavement, the quicker heat will be drawn out of the asphalt. Heat loss ... for the types of asphalt mix being placed. Roller capacity must also be matched to the rate of delivery of asphalt and asphalt paver speed. A guide to

Approximately 500 million tons of hot mix asphalt (HMA) are placed in the United States each year. With this large quantity of HMA, it is expected that some construction problems will occur from time to time. One problem that has been observed for years, on a small percentage of projects is tenderness of some mixtures during compaction.

It's essential to complete rolling before the mix temperature drops too low to achieve target density. This practice allows the highest production to be achieved and, for mixes exhibiting tenderness, proper breakdown rolling density can be reached before the mix becomes unstable or develops a tender zone.

General Information for Hot Mix Asphalt Operations. BINDERS (OILS) Two grades of asphalt binders have been historically available and used in Both the Monterey and San Francisco Bay areas, AR 4000 & AR 8000. AR 4000 has been widely used historically. The …

Editor's note: This is the second installment of a two-part series on asphalt compaction.In the August issue, Scherocman, a consulting engineer in pavement design and construction located in Cincinnati, discussed the importance of compaction and the relationship between density and the air-void content of hot-mix asphalt (HMA) pavement.For an HMA to perform well under traffic, it must be ...

It has been reported that with proper aggregate characteristics and asphalt content, HMA with PG 64-22 as the binder may exhibit less tenderness than a similar mixture with a lower viscosity/softer asphalt. The typical tenderness problems of mixture shoving and checking during rolling and pavement surface scuffing and marking by traffic ...

A similar cas e of surface tenderness was reported at . ... some 95% of asphalt mix tures and has a signi ficant impact on the mechanical prop erties of a surface . layer [61].

To the Graduate Council: I am submitting herewith a thesis written by Pawel Andrzej Polaczyk entitled "EVALUATION OF THE HOT MIX ASPHALT COMPACTABILITY UTILIZING THE IMPACT COMPACTION METHOD." I have examined the final electronic copy of this thesis for form and content and recommend that it be accepted in partial fulfillment of the requirements for the degree of Master of …

If transporting hot asphalt concrete at prevailing air temperatures below 50 ° F (10 ° C) or if the length of haul exceeds 20 miles (32 km), ensure that all truck beds are insulated to maintain workable mix temperature, and that all covers are fastened to exclude the wind. Do not exceed a distance of 50 miles (80 km) from the asphalt concrete ...

effects of asphalt properties on indirect tensile strength The indirect tensile test on asphalt concrete mixes is a frequently used procedure for assessing likely pavement performance. Currently, the indirect tensile test is most commonly used for providing information on moisture susceptibility.

Texas Asphalt Pavement Alliance Summary & Conclusions ¾Match the HMA type to the application Comfort, Safety, Durability, Cost Effectiveness Consider life cycle costs –Vs- initial cost ¾Performance is a function of mix type, aggregate quality, asphalt quality and quantity and existing structure ¾Finer mixes = thinner lifts = less cost/SY

This condition is known as "tenderness" in the asphalt. It usually occurs in finer mixes but can occur in any hot mix. It is caused by a high asphalt cement (asphalt binder) coupled with a …

A"tender" asphalt mix usually refers to a mix that is difficult to compact. It may have a tendency to shove under the roller wheels and/ or leave longitudinal cracks at the edge of the steel drums. Either a lack of friction between particles or a lack of shear strength in the mix essentially causes tenderness. Both these problems can be the result of many factors, the most common of which ...

High Temperature Tenderness Some HMA mixes exhibit tenderness (low mix viscosity) at high temperatures, typically seen as pushing and shoving under the initial breakdown rollers. Likely causes for high temperature tenderness include excess sand or excess asphalt binder in the mix.

4 revolutions. The voids at Ninitial is supposed to indicate the tenderness of the mix during compaction, and the percent of maximum theoretical density should be less than 89. Voids at Ndesign should coincide with the design VTM, 4 percent, which represents the mix after construction and trafficking.

Minimal asphalt plant modifications were required to accommodate the warm-mix additives. No problems were noted with producing the asphalt mixes at the lower temperatures. The target mix production temperatures (i.e., 155°C and 120°C [310°F and 250°F]) were achieved.

The best method of controlling exposure to asphalt fumes and solvent vapors is to substitute a safer asphalt mix. If explosion hazards are a problem in a paving operation, Medium Cure (MC)-250 may be substituted for Rapid Cure (RC)-250. The flashpoint of the mix is nearly doubled, which means that the mix is less likely to ignite.

Hot Mixed Asphalt (Bituminous Concrete) Asphalt Hot Mix RECOMMENDED USE AND RESTRICTION ON USE Used for construction purposes This product is not intended or designed for and should not be used as an abrasive blasting medium or for foundry applications. ... Contact a physician if irritation, pain, swelling, lacrimation or photophobia persist or ...

Identifying a Tender Mix • "Tender asphalt mixes" should not be confused with the "Tender zone" but they can be related • Tender asphalt mixes are those that exhibit excessive lateral displacement, shoving, and/or check cracking while being compacted. • The "tender zone" exists when the hot mix temperature is generally between ...

Begin warm mix asphalt (WMA) production gradually and lower the mix temperature to within + 10°F of the WMA target temperature. 3. Check loaded transports to assure that the mix tempera- ... signs of tenderness, allow mat to drop 10-15°F and resume rolling. Image courtesy of Plantmix Asphalt Industry of Kentucky. Ingevity Corporation

periods of mix tenderness. Mix production at asphalt plant #2 was less consistent with binder contents ranging between 7.6 percent and 10.0 percent. Three of the mixes were below the target binder content, one was close to the target binder content and the other significantly higher than the target. This

Asphalt Paving Operation. The subject of this term project was an asphalt paving process utilizing a paving machine and 20 tons capacity tri-axle trucks. The location of the process was at the corner of Main and Madison in Greenwood ( South of Indianapolis ). The project is being run by the Reith-Riley Construction Company.

Specifications Allow Over-Sanded Mixes. All mix designs allow gradations that will cause tenderness and accelerate rutting. If the proper maximum density line is used, such mixes are readily detected, however that is not so with the worthless maximum density line in the present design procedure. Rutting is highly dependent upon where the VMA in ...

For surface JMFs having polymer asphalt binder only submit at 0 or 10% RAP. If greater than 20 percent RAP is used in a JMF submittal include an analysis of the recovered asphalt binder and blend per Level 3 Mix Design procedures to determine the grade of asphalt binder to use. TABLE 401.04-1 Method 1 – Standard RAP Limits Asphalt Mix

Asphalt C is highly temperature susceptible and reputed to produce very tender and slow-setting mix­ tures. Asphalt C exhibited the lowest initial vis­ cosity at 77°F and a relatively slow setting rate compared to the other asphalts tested. It appears that the problems associated with this asphalt are

One of the major consequence of moisture damage to asphalt concrete is mix tenderness. The escape of residual moisture reduces asphalt binder film stiffness and thus reduces the stiffness of the mix. The lower mix stiffness increases the cracking potential along the roller edge and causes unevenness at the end of rolling that increases pavement ...

A tender mix is an internally unstable mix that tends to displace laterally and shove rather than compact under roller loads. Internal mix stability is a function of asphalt binder viscosity and aggregate gradation and shape. Mix tenderness is usually one of two varieties (TRB, 2000 [1]): High temperature tenderness. At high temperatures some ...

HOT MIX ASPHALT TENDER ZONE E.R. Brown, Byron Lord, Dale Decker, and Dave Newcomb INTRODUCTION Approximately 500 million tons of hot mix asphalt (HMA) are placed in the United States each year. With this large quantity of HMA, it is expected that some construction problems will occur from time to time.

Conclusions Incorporating RAP to ed asphalt mix and tested with indirect tensile strength test under dry condition shows that RAP contents did not offer significant effect on tensile strength of the mixes. This shown by statistical analysis two-way ANOVA with probability value obtained is more than the predetermined alpha value (p = .323 ...

Approximately 500 million tons of hot mix asphalt (HMA) are placed in the United States each year. With this large quantity of HMA, it is expected that some construction problems will occur from time to time. One problem that has been observed for years, on a small percentage of projects is tenderness of some mixtures during compaction.

Too much asphalt cement makes the mix tender and difficult to compact to the proper density. Asphalt cement with a low viscosity at compacting temperatures can also make a mix tender as can too much natural sand because it has smooth, round grains. ... and tenderness. Incorporate enough air voids to prevent bleeding but not so much as to reduce ...

The Hot-Mix Asphalt Paving Handbook 2000 (TRB, 2001) and the Asphalt Institute's HMA Construction Manual ... excessive binder content, and excessive moisture. Overcoming this tenderness state may be as simple as waiting several minutes for the mixture to cool slightly, or as problematic as developing a new mixture design. ...

Asphalt Tenderness in an Australian Runway Overlay. March 2016; ... that the likely cause of the deformations at Melbourne Airport was a lack of resistance to Cyclic Shear Creep in the asphalt mix ...

All are critical to a well performing and durable asphalt mix. What is the density of asphalt binder? 1.00 g/cm3 The mixing temperature range is defined as the range of temperature where the unaged asphalt binder has a kinematic viscosity of 170 + 20 mm2/s (approximately 0.17 + 0.02 Pa-s for an asphalt binder density of 1.00 g/cm3) measured in ...