Soils Testing Technician

The Soils Testing Technician course covers laboratory and field tests related to earthwork, with particular emphasis on soil classification, plasticity index, moisture-density relationships, and nuclear density.

Course Options

There are two course options, including in-person and test only.

  1. The standard 2 ½ day in-person course is required for new technicians.
  2. The Test Only Option requires technicians to view online training modules and successfully complete an online quiz prior to the testing date. The technician will then attend an in-person testing session to complete written and performance exams.

Soils - Test Only Option

Pre-Requisite Requirements

The Basic Aggregates Testing Technician course is a required pre-requisite for the Soils Testing Technician course.  The Soils course is not intended to provide basic training, but rather to serve as a refresher and evaluation leading to certification.  Prior to attending the course, participants should have a working knowledge of soil testing methods, as well as the mathematical calculations associated with those methods.  Experience in physically performing these test methods is strongly recommended.  Online review materials may also be beneficial in preparing for the class.

Soils Review Materials


The procedures covered in this course are those prescribed by the Arkansas Department of Transportation (ARDOT) Standard Specifications for Highway Construction and related specifications, including:

  • AASHTO M 145 Classification of Soils and Soil-Aggregates Mixtures for Highway Construction Purposes
  • AASHTO M 146 Terms Relating to Subgrade, Soil-Aggregate, and Fill Materials
  • AASHTO R 58 Dry Preparation of Disturbed Soil and Soil Aggregate Samples for Test
  • AASHTO T 89 Determining the Liquid Limit of Soils
  • AASHTO T 90 Determining the Plastic Limit and Plasticity Index of Soils
  • AASHTO T 99 Moisture-Density Relations of Soils Using a 2.5-kg (5.5-lb) Rammer and a 305-mm (12-in.) Drop
  • AASHTO T 180 Moisture-Density Relations of Soils Using 4.54kg(10lb.) Rammer and a 457mm(18in.) Drop
  • AASHTO T 265 Laboratory Determination of Moisture Content of Soils
  • AASHTO T 310 In-Place Density and Moisture Content of Soil and Soil-Aggregate by Nuclear Methods (Shallow Depth)
  • ARDOT 30 Sampling Soils
  • ARDOT 347 Determining Moisture Content by Speedy Moisture Tester

Supplies and Equipment

All necessary equipment and supplies used in the Soils Testing Technician course will be furnished by CTTP.  A course notebook and pencil is provided to each participant.  Calculators may be borrowed from CTTP; however, participants are often more comfortable bringing a calculator with which they are familiar, and routinely use.  Other items that may be useful include a straightedge or ruler, pen, pencil, and highlighter.

CTTP course participants are required to wear applicable personal protective equipment in the laboratory, including long pants, closed-toe shoes, and safety glasses.  Safety glasses, gloves, and other personal protective equipment may be borrowed from CTTP during the class.

Although this course requires the use of the nuclear density gauge, no active sources are used during the class.  Thus, participants are no longer required to have a dosimeter in order to attend the CTTP Soils Testing Technician course.  Note that any work using radioactive sources requires compliance with Arkansas Department of Health (ADH) regulations.

Course Schedule

Each Soils Testing course will begin at 1:00 pm on Day 1 unless otherwise stated, with check-in from 12:30 pm to 1:00 pm.  Classroom and laboratory instruction will be provided on Day 1 and Day 2.  Written and performance exams will be given on Day 3, with the course concluding no later than 4:00 pm on Day 3.  More information can be found in the Detailed Course Schedule.  Participants who do not attend the entire class will not be allowed to take the exams.


The Soils Testing Technician certification requires a passing score on both a written and a performance exam.  The written exam is closed-book, and subject to a two-hour time limit.  In order to receive certification, a minimum of 70% of all questions must be answered correctly on the written portion of the exam.

Performance exams must be performed individually, and are graded on a “pass/fail” basis.  Participants must perform all methods correctly in order to pass the performance portion of the course.  Two attempts are allowed at each station. The Soils Testing performance exam consists of multiple stations, including:

  • AASHTO T 89 Determining Liquid Limit of Soils
  • AASHTO T 90 Determining the Plastic Limit and Plasticity Index of Soils
  • AASHTO T 99 Moisture-Density Relations of Soils Using a 2.5-kg (5.5-lb) Rammer and a 305-mm (12-in.) Drop
  • AASHTO T 310 In-Place Density and Moisture Content of Soil and Soil-Aggregate by Nuclear Methods (Shallow Depth)

Participants who do not pass the Soils Testing Technician course by failure of either the written or performance exam will be required to repeat the entire course.


Upon successful completion of both the written and performance exams, participants will receive a five-year CTTP certification in Soils Testing.  Certified individuals will receive a CTTP certificate and pocket card, and will be added to the CTTP website list of Certified Technicians.  Expiration dates occur on a semi-annual basis: June 30 or December 31 after the five-year certification period.

Recertification in Soils may be achieved by either:

  1. Successful completion of the standard 2 ½ day Soils Testing Technician course, or
  2. Successful completion of the Soils Testing Technician – Test Only Option.

All policies pertaining to each of these options will apply.

Reciprocity requests will be considered on a case-by-case basis for Soils Testing Technician.


ARDOT employees may register for this course by contacting Dorothy Rhodes at .  All others should Click Here to Register.  Applicable fees will be assessed.