Long Term Pavement Performance Project Laboratory Materials Testing and Handling Guide

Protocol P62
Test Method for Determinationof Splitting Tensile Strengthof PCC Cores/Cylinders (Pc02)

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. Core: An intact cylindrical specimen of the pavement material that is removed from the pavement by drilling at the designated location. A core can consist of, or include, one, two or more different layers.
2. Layer: That part of the pavement produced with similar material and placed with similar equipment and techniques. The material within a particular layer is assumed to be homogeneous. The layer thickness can be equal to or less than the core thickness or length.
3. Test Specimen: That part of the layer which is used for the specified test. The thickness of test specimens cored from the pavement can be equal to or less than the layer thickness.

1. SCOPE

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. APPLICABLE DOCUMENTS

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. TEST SPECIMENS

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.

7. REPORT

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:

1. Diameter (D) to the nearest 0.01 inches.
2. Length (L) to the nearest 0.1 inches.
3. Maximum load, in pounds-force.
4. Splitting tensile strength (STS) calculated to the nearest 1 psi.
5. Type of fracture, as described with a code and note in Section 9.3(g) of LTPP Protocol P61.
6. Length to diameter (L/D) ratio.

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.

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) __