Automation vs. Manual Control in Concrete Testing

Concrete is one of the most widely used materials around the world. The construction industry is often involved in a wide array of testing which requires a variety of testing equipment. In addition to simple compression testing, testing standards such as ASTM C39, ASTM C109, ASTM C469, ASTM C1609 are among the test methods that can be followed to measure the mechanical properties of a concrete specimen. This blog post covers the mechanical testing of concrete in lab environments, its automation, and ways of achieving it.

Mechanical Testing of Concrete

In order to determine that the mechanical properties of a concrete specimen meet the strength and deflection requirements for its intended application, concrete samples with specific dimensions are prepared, mold cured, and tested following the appropriate instructions or a standardized test method. At the end of the tests, strength reports are created either manually or by automatic analysis.

Automation in Concrete Testing and Ways of Achieving It

Benefits of concrete testing with automatic control include reduction of testing times, elimination of data entry errors, and the increased speed in delivering the results. Automation includes the automatic control of the machine as well as the automatic calculation of the tested properties. When a machine is servo-controlled, it is operated through a controller or its software. The test procedure to be run and the analyses to be calculated are entered in the system and results are automatically generated.

An important note to add here is that certain features of full-automation can be made feasible by adding digital indicators to manually operated systems. Reliable indicators designed for the concrete industry can combine client, contractor, mixture proportion, and field data with the calculated compressive strength data such as peak load or the breaking strength with user-selected parameters including date, time, specimen number, specimen geometry and break type. Certain indicators also allow the use of concrete testing software. Test results can be transferred to a computer running a database program and automatically imported.

Is Manual or Automated Operation more appropriate for my concrete testing?

Manually operated systems are often sufficient for concrete testing applications. Nevertheless, certain test standards governing the concrete industry require strain rate feedback that is not possible to achieve with manual operation.

For some concrete tests, it is required to have verifiable loading rate throughout the testing as concrete exhibits loading-rate sensitivity relative to compressive strength. Certain ASTM standards, such as ASTM C39, specify or limit the loading rate to a certain value or a range in order to ensure consistency within and among laboratories. When equipped with the right digital indicator, the average loading rate can be calculated and reported according to ASTM C39 requirements even if the testing was performed on a manually controlled machine. In addition to other features specifically beneficial for the concrete industry, depending on the selected digital indicator, load and stress versus time data and curves can be generated.

For others, such as ASTM C1609, it is necessary to maintain a low, constant speed throughout the test. Digital indicators do not control the testing machines, so operators are required to manually adjust a valve to achieve the specified rates. Hence, it is not possible to accurately follow standards that require constant low speed testing with manually operated systems. Servo-control equipment with controllers that are used to control the movement of the machine is recommended for such testing. 

Concrete Testing Equipment

ADMET offers a range of equipment for concrete testing, including indicators (Pi indicators, DFG Concrete Indicator, GaugeBuster 2) to be used with existing manually-controlled systems, controllers to retrofit servo-control machines, the MegaForce Testing System specifically made for concrete testing, as well as servo-control machines (eXpert 2600, eXpert 1600) that allow a variety of concrete testing to be conducted on a single system while generating accurate and repeatable results. Furthermore, ADMET works to meet unique customer requirements and has the ability to engineer customized systems.

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