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Publication Number: FHWA-RD-07-052
Date: September 2007
This LTPP protocol covers the determination of the splitting tensile strength of PCC cores and molded cylinders. The test shall be carried out in accordance with AASHTO T198-88I as modified by the following. Only sections of the referenced standard which have been modified are included below. In all other sections the standard (AASHTO T198-88I) shall be followed as written. The test shall be performed on cores or molded cylinders obtained from LTPP projects. The specimens to be tested are as shown on the materials testing plans developed for each project.
For PCC pavement cores consisting of multiple layers, the test shall be conducted separately on the core specimens consisting of each of the concrete overlay layers and the original concrete pavement layer from each specified location after assigning proper layer numbers. Layer numbers shall be assigned using the field layer number information from Field Operations Information Form 2 of the field data packet or lab sheet L04. The following definitions will be used throughout this protocol.
1.1 This test covers the determination of the splitting tensile strength of cores or molded cylinders obtained from a GPS or SPS pavement project.
2.1 AASHTO Standards: AASHTO T22-88I, AASHTO T24-86, AASHTO T67-85
2.2 LTPP Protocol: P66 - Visual Examination and Thickness of Portland Cement Concrete Cores/Cylinders.
4.1 The test specimen shall be prepared following the procedure of Sections 7.1-7.3 of AASHTO T24-86.
4.2 The test specimen shall be sawed and/or ground to achieve a uniform length, and the end surfaces shall conform to Section 6.2 of AASHTO T24-86. The length to diameter ratio shall be as nearly as practicable between 1 and 2; in any case the length to diameter ratio shall not exceed 2.5. In order to comply with these requirements, the test specimen is required to be trimmed as not to exceed one inch at the bottom of the specimen and up to ½ inch (13 mm) at the top of the specimen. The finished ends are not to be capped.
4.3 PCC cores, retrieved from the pavement, are marked with an arrow or other symbol to show the direction of traffic. It is important that this orientation mark be transferred to the trimmed surface of the PCC core if the core is trimmed to comply with the requirements of Section 4.2. After trimming, the PCC specimen that will be used for testing will no longer contain the arrow or other symbol that was marked during the drilling operations. Therefore, the participating laboratory is required to adhere to the following rule:
If any PCC core requires trimming at the top, then the laboratory technician shall paint the same arrow or other traffic direction symbol on the trimmed surface that is marked on the surface of the core. The arrow or other symbol shall be placed along the same axis to designate the direction of traffic on the pavement surface. The face to be marked shall be the one closest to the pavement surface.
4.4 Measure the average diameter (D) of the test specimen to the nearest 0.01 inch (0.25 mm) following Section 5.2 of AASHTO T198-88I.
4.5 Determine the length (L) of the test specimen to the nearest 0.1 inch (2.5 mm) in accordance with Section 5.2 of AASHTO T198-88I.
4.6 PCC cores (obtained from the pavement) shall be stored flat side down, fully supported and at between 5 ° C (40 ° F) and 38 ° C (100 ° F) in an environmentally protected storeroom.
PCC cylinders (molded in the field) shall be moist cured during storage prior to testing at 23 ± 1.7 ° C (73.4 ± 3 ° F). As applied to the treatment of demolded specimens, moist curing means that the test specimens shall have free water maintained on the entire surface at all times. The moist room shall meet the requirements of AASHTO Specification M201. Specimens shall not be exposed to dripping or running water.
Prior to performing the test, the cores or cylinders shall be submerged in lime-saturated water at 23 ± 1.7 ° C (73.4 ± 3 ° F) for at least 40 hours immediately prior to performing the test.
The following information is to be recorded on Form T62:
7.1 Sample Identification shall include: Laboratory Identification Code, Region, State, State Code, SHRP ID, Layer Number, Field Set Number, Sample Area Number, Sample Location Number, LTPP Sample Number.
7.2 Test identification shall include: LTPP Test Designation, LTPP Protocol Number, Laboratory Test Number, Test Date.
7.3 Test Results
Report the following:
7.4 Comments shall include LTPP standard comment code(s) as shown in Section 4.3 of this Guide and any other note, as needed. Additional codes for special comments associated with the testing are given below.
|31||Length to diameter ratio was equal to or less than 1.0 because the layer thickness was less than the diameter of the specimen.|
|32||The specimen was trimmed only at the bottom end.|
|33||The specimen was trimmed only at the top end.|
|34||The specimen was trimmed at the bottom and top ends.|
|35||The line of contact between the specimen and each bearing strip was straight and free from any projections or depressions higher or deeper than 0.01 inches (0.25 mm).|
|36||The line of contact described in code 35 above was made possible by grinding.|
|37||The line of contact described in code 35 above was made possible by capping, or by grinding and capping.|
|38||The line of contact between the specimen and each bearing strip had more than 0.01-inch (0.25-mm) tolerance as described in Code 35 but less than 0.1-inch (2.5-mm) tolerance. The specimen was tested.|
|39||The projections/depressions on the test surface (as described in Code 35) were higher or deeper than 0.1 inch (2.5 mm). The specimen was tested because there was no other replacement specimen.|
|40||The PCC core retrieved from the field did not have any arrow or "T" to show the direction of traffic.|
7.5 Use form T62 (Test Sheet T62) to report the above information (Items 7.1 to 7.4).
LTPP LABORATORY MATERIAL HANDLING AND TESTING
LABORATORY MATERIAL TEST DATA
SPLITTING TENSILE STRENGTH OF PCC CORES
LAB DATA SHEET T62
PORTLAND CEMENT CONCRETE
TEST DESIGNATION PC02/PROTOCOL P62
LABORATORY PERFORMING TEST:______________________________________________________________
LABORATORY IDENTIFICATION CODE: __ __ __ __
REGION _________________ STATE ___________________ STATE CODE __ __
EXPERIMENT NO _____ SHRP ID __ __ __ __
SAMPLED BY: ______________________________________________ FIELD SET NO. __
DATE SAMPLED: __ __-__ __-__ __ __ __
1. LAYER NUMBER (FROM FIELD OPERATIONS FORM 2 AND/OR LAB SHEET L04) __
|2. SAMPLING AREA NO. (SA-)||__ __||__ __|
|3. LABORATORY TEST NUMBER||__||__|
|4. LOCATION NUMBER||__ __ __||__ __ __|
|5. LTPP SAMPLE NUMBER||__ __ __ __||__ __ __ __|
|6. DIAMETER (D), INCHES||__.__ __||__.__ __|
|7. SPECIMEN LENGTH (L), INCHES||__ __.__||__ __.__|
|8. MAXIMUM LOAD, LBF||__ __ __ __ __ __.||__ __ __ __ __ __.|
|9. SPLITTING TENSILE STRENGTH (STS), PSI||__ __ __ __.||__ __ __ __.|
|TYPE OF FRACTURE (FR)|
|(a) CODE||__ __||__ __|
|11. L/D RATIO||__.__ __||__.__ __|
|(a) CODE||__ __ __ __ __ __||__ __ __ __ __ __|
|__ __ __ __ __ __||__ __ __ __ __ __|
|13. TEST DATE||__ __-__ __-__ __ __ __||__ __-__ __-__ __ __ __|
|SUBMITTED BY, DATE||CHECKED AND APPROVED, DATE|
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Topics: research, infrastructure, pavements and materials
Keywords: research, infrastructure, pavements and materials, Asphalt cement, asphalt concrete, field sampling, General Pavement Studies, laboratory testing, LTPP, material properties, pavement layering, Pavement Performance Data Base, portland cement concrete, protocol,Specific Pavement Studies, subbase, subgrade, treated base, unbound base
TRT Terms: research, facilities, transportation, highway facilities, roads, parts of roads, pavements