ASTM C31 and C39 Concrete Cylinder Testing: A Checklist for Evaluating Concrete Testing Software

What to Look for at Every Step From the Truck to the Break Report

In concrete cylinder testing, every break is the last step in a longer process. Before a set reaches the compression machine, a field tech sampled the load, ran slump, air, and temperature, cast and rodded the cylinders, protected them through initial cure, and got them to the lab. ASTM C31 and C39 govern that process, and the documentation at each step is what makes the break result defensible.

For construction materials testing (CMT) firms, that record is also where concrete testing software earns its place. This checklist follows each step from the truck to the break report, summarizes what the standards call for in the field and lab, and lists what to look for in software that helps your team capture it. Use it to evaluate a new platform or to review the one you run today.

What Should Concrete Testing Software Do for ASTM C31 and C39?

Concrete testing software should capture fresh concrete tests and cylinder data at the truck, generate cylinder IDs tied to the work order, require initial cure documentation, notify the lab before cylinders arrive, schedule breaks from the cast date, flag low breaks, and build the break report from one connected field and lab record.

What Do ASTM C31 and C39 Cover?

ASTM C31 is the standard practice for making and curing concrete test specimens in the field. It covers casting cylinders at the truck, initial cure, and transport to the lab.

ASTM C39 is the standard test method for compressive strength of cylindrical concrete specimens. It covers breaking cylinders in a compression testing machine, calculating compressive strength, and recording the fracture type.

Together, the two standards run from the pour to the break report. A reliable C39 break depends on a cylinder cast and cured per C31, so field and lab records work best as one connected record.

Which Other ASTM Test Methods Support Cylinder Testing?

Several other standards feed the cylinder record. Fresh concrete values recorded at the truck are the first context an engineer reviews when a result needs explaining.

The Checklist: What to Look for in Concrete Testing Software

Each step below pairs what the standard calls for with the software capabilities that help your team document it.

What Else Should Concrete Testing Software Include?

The standards define what goes into the record. These capabilities help your team capture it consistently across every project.

• Offline capture: Forms work without signal and sync automatically when the connection returns.
• Consistency across technicians: The same fields, units, and location conventions apply on every record, whoever fills it out. It's a natural complement to ACI Concrete Field Testing Technician Grade I certification.
• One connected record: The field form, lab intake, break schedule, and break report live in one system instead of separate files.
• Ready-to-use forms: ASTM C31 sampling forms and ASTM C39 break report templates come prebuilt, so setup focuses on your projects and specifications.
• Role-based views: Field technicians, lab managers, and project managers each see the information they act on.

1. Sampling and Fresh Concrete Tests

What the standard calls for: ASTM C172 calls for a composite sample from the middle portion of the load. Fresh tests start within 5 minutes of obtaining the sample, and casting cylinders starts within 15 minutes. Slump, air content, temperature, and unit weight are recorded at the sample.

What to look for:

• Fresh concrete tests and cylinder casting captured on the same form
• Time stamps for sampling, fresh tests, and casting
• Required fields for slump, air content, temperature, and unit weight
• Consistent units and formats across every technician

2. Casting and Identifying Cylinders

What the standard calls for: ASTM C31 defines cylinder size (typically 4x8 or 6x12 inch), consolidation method (rodding or vibration, based on slump), and layer counts. Each cylinder needs an ID that ties it to the pour, mix design, work order, and placement location.

What to look for:

• Fields for cylinder size and consolidation method
• Unique cylinder IDs generated by the system when the set is cast
• Each ID linked to the work order, mix design, and placement location
• Work order details that pre-populate, so technicians confirm instead of re-entering

3. Initial Curing Documentation

What the standard calls for: ASTM C31 calls for initial curing at 60 to 80°F for 24 ± 8 hours, with cylinders protected from sunlight, vibration, and disturbance.

What to look for:

• Required fields for curing temperature, curing method, and storage location
• A record that can't be submitted with curing conditions left blank
• Field-cured specimens tracked separately from standard-cured specimens

4. Transport and Chain of Custody

What the standard calls for: ASTM C31 calls for moving specimens to the lab after initial curing, protected from damage, within 4 hours of leaving the site.

What to look for:

• Cylinder IDs stored in the data record, not only on a physical label
• Handoffs logged from field to courier to lab
• Lab notification when the field record is submitted

5. Lab Intake and Curing Records

What the standard calls for: Standard-cured cylinders go into the moist room or curing tank at 73.4 ± 3°F and 95% relative humidity or higher. The curing log and compression machine calibration records are part of the record.

What to look for:

• Intake records created from the field submission
• Expected sample counts visible before cylinders arrive
• Curing room logs and equipment calibration records stored with the project

6. Break Scheduling Against Age Tolerances

What the standard calls for: ASTM C39 sets age tolerances for each test age, such as ± 20 hours for a 28-day break and ± 6 hours for a 7-day break.

What to look for:

• Break dates calculated from the actual cast date
• Upcoming and overdue breaks flagged in the lab's queue
• Schedules that update when the field record changes

7. Break Results, Fracture Type, and Reporting

What the standard calls for: ASTM C39 calls for recording specimen dimensions, cross-sectional area, loading rate 35 ± 7 psi/s, maximum load, compressive strength, and fracture type (Types 1 to 6).

What to look for:

• Compressive strength calculated from entered dimensions and load
• A fracture type field on every break
• Automatic flags when a result falls below the specified strength (f'c)
• Break reports that pull pour location, mix design, fresh test values, and curing history from the field record