SECTION 404 – STONE MATRIX ASPHALT (SMA)
404.01 Description
This Section describes the requirements for constructing stone matrix asphalt (SMA) surface course.
404.02 Materials
404.02.01 Materials
Provide materials as specified: Tack Coat ................................ ................................ ................................ ................................ ................ 902.01.02 Polymer Modified Emulsified Asphalt, Grade CRS-1P ................................ ................................ ............. 902.01.03 Stone Matrix Asphalt ................................ ................................ ................................ ................................ .... 902.05
404.02.02 Equipment
Provide equipment as specified: Materials Transfer Vehicle (MTV) ................................ ................................ ................................ .............. 1003.01 HMA Paver ................................ ................................ ................................ ................................ ................. 1003.03 HMA Compactor ................................ ................................ ................................ ................................ ........ 1003.05 Vibratory Drum Compactor ................................ ................................ ................................ ......................... 1003.06 HMA Plant................................ ................................ ................................ ................................ .................. 1009.01 HMA Trucks ................................ ................................ ................................ ................................ ............... 1009.02 Provide a thin-lift nuclear density gauge according ASTM D 2950. NOTE: A Spray Paver as specified in 1003.04 may be used in lieu of a HMA Paver.
404.03 Construction
404.03.01 Stone Matrix Asphalt Surface Course
A.Paving Plan. At least 20 days before the start of placing the SMA, submit to the RE for approval a detailed plan of operation as specified in 401.03.07.A.
B.Weather Limitations. Do not place SMA if it is precipitating. Do not allow trucks to leave the plant when precipitation is imminent. The Contractor may resume operations when the precipitation has stopped and the surface is free of water. Do not pave if the base temperature is below 50 °F.
C.Test Strip. Construct a test strip as specified in 401.03.07.C.
D.Transportation and Delivery of HMA. Transport and deliver HMA as specified in 401.03.07.D.
E.Spreading and Grading. Apply tack coat as specified i n 401.03.05. Place SMA at a laydown temperature of at least 285 °F. Spread and grade SMA as specified in 401.03.07.E. Ensure that the screed is operated in the vibratory mode. If constructing a cold longitudinal joint, construct a butt joint. Do not rake the joint.
F.Compacting. Compact as specified in 401.03.07.F. Ensure that the compaction is completed before the mix cools down to 240 °F. If vibratory compaction causes aggregate breakdown or forces liquid asphalt binder to the surface, operate rollers in static mode only.
G.Opening to Traffic. Open to traffic as specified in 401.03.07.G.
H.Air Void Requirements. Drill cores as specified in 401.03.08. Mainline lots are defined as the area covered by a day’s paving production of the same job mix formula for the traveled way and auxiliary lanes. The RE may combine daily production areas less than 1,000 tons with previous or subsequent production areas. If a day’s production is greater than 4 ,000 tons, the RE may divide the area of HMA placed into 2 lots with approximately equal areas. Ramp pavement lots are defined as approximately 10,000 square yards of pavement in ramps. The RE may combine ramps with less than the minimum area into a single lot. If 2 or more ramps are included in a single lot, the RE will require additional cores to ensure that at least 1 core is taken from each ramp. Other pavement lots are defined as approximately 10,000 square yards of pavement in shoulders and other undefined areas. The ME will calculate the percent defective (PD) as the percentage of the lot outside the acceptable range of 1 percent air voids to 7 percent air voids. The acceptable quality limit is 10 percent defective. For lots in which PD < 10, the Department will award a positive pay adjustment. For lots in which PD > 10, the Department will assess a negative pay adjustment. The ME will determine air voids from 5 cores taken from each lot in random locations. The ME will determine air voids of cores from the values for the maximum specific gravity of the mix and the bulk specific gravity of the core. The ME will determine the maximum specific gravity of the mix according to NJDOT B-3 and AASHTO T 209, except that minimum sample size may be waived in order to us e a 6 inch diameter core sample. The ME will determine the bulk specific gravity of the compacted mixture by testing each core according to AASHTO T 166. The ME will calculate pay adjustments based on the following:
1.Sample Mean (X̅ ) and Standard Deviation (S) of the N Test Results (X 1, X2,..., XN). Calculate using the formula as specified in 401.03.07.H.1.
2.Quality Index (Q). QL = (X̅ − 1.0) S QU = (7.0 − X̅) S
3.Percent Defective (PD). Using NJDOT ST for the appropriate sample size, the Department will determine PDL and PDU associated with QL and QU, respectively. PD = PDL + PDU
5.Outlier Detection. If PD < 10, the ME will not screen for outliers. If PD ≥ 10, the ME will screen all acceptance cores for outliers using a statistically valid procedure. The following procedure applies only for a sample size of 5 or 10.
1.The ME will arrange the core results in ascending order, in which X1 represents the smallest value and XN represents the largest value.
2.If XN is suspected of being an outlier, the ME will calculate: R = XN − X(N−1) XN − X1
3.If X1 is suspected of being an outlier, the ME will calculate: R = X2 − X1 XN − X1
4.For N = 5 if R > 0.642, the value is judged to be statistically significant and the core is excluded. For N = 10 if R > 0.412, the value is judged to be statistically significant and the core is excluded. If an outlier is detected for N = 5 and no retest is warranted, the Contractor may replace that core by taking an additional core at the same offset and within 5 feet of the original station. If an outlier is detected and a retest is justified, take a replacement core for the outlier at the same time as the 5 additional retest cores are taken. If the outlier replacement core is not taken within 15 days, the ME will use the initial core results to determine PPA. If an outlier is detected for N = 10, the Contractor may replace that core by taking an additional core at the same offset and within 5 feet of the original station. If the outlier replacement core is not taken within 15 days, the ME will use the initial core results to determine PPA.
6.Retest. If the initial series of 5 cores produces a percent defective value of PD 30 for mainline or ramp lots, or PD 50 for other pavement lots, the Contractor may elect to take an additional set of 5 cores at random locations chosen b y the ME. Notify the RE within 15 days of receipt of the initial core results to take the additional cores. If the RE is not notified within the 15 days, the ME will use the initial core results to determine the PPA. If the additional cores are taken, the ME will recalculate the PPA using the combined results from the 10 cores.
7.Removal and Replacement. If the final lot PD 75 (based on the combined set of 10 cores or 5 cores if the Contractor does not take additional cores), remove and replace the lot and all overlying work. The replacement work is subject to the same requirements as the initial work. For shoulder lots, the Department will assess the calculated PPA instead of removal and replacement. Fog seal the lot as specified in 422.03.01.
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Source: Standard Specifications for Road and Bridge Construction, 2019 (rev. 2022-12-21) Edition. Pages 206–208 of 651. View official source ↗