ASTM Grout Testing for Cement Tests in Masonry Construction
Grout testing is a big part of the construction industry especially in masonry. Grout is a critical component of masonry structures, gives strength, stability and durability to the building. But grout can be prone to defects and inconsistencies which can compromise the structure. These tests help identify these defects and ensure the grout meets the required standards for quality control purposes. By doing tests, construction professionals can detect problems early and ensure the longevity and safety of the structure. This section will cover the importance of testing, types of tests and the benefits of high construction standards.
Taking Samples for Testing Grout
Taking grout samples for testing is a big part of the testing process. To ensure the sample is representative of the grout used in the construction project, take the sample from the middle third of the grout discharge. Follow proper sampling procedures, take two or more grout portions at regular intervals during the discharge process. Each portion should be combined and thoroughly mixed to form representative test samples. Prior to molding specimens, it is important to remix the grout to eliminate air bubbles and ensure uniformity. Mix the portions with a shovel or trowel before molding the specimens. A grout sample size of 12 ft³ is required for testing. Store the grout sample properly by keeping it in a cool, dry location away from direct sunlight and moisture.
Taking grout samples at specific intervals during the discharge process is crucial to ensure accuracy and reliability in testing.
Grout Compressive Strength Requirements
Grout compressive strength requirements vary depending on the type of construction project and the application of the grout. Generally grout compressive strength should be at least 1,000 psi (6.9 MPa) for most masonry projects. But some projects may require higher compressive strength values like 2,000 psi (13.8 MPa) or more to meet specific structural requirements. These requirements should be specified in the construction project specs to ensure compliance and structural integrity. Adhering to these standards is crucial for ensuring safety and durability. The Specification for Masonry Structures provides guidelines to ensure compliance and quality assurance in compressive strength testing and application.
Preparation and Sampling
Preparation and sampling are foundational steps in achieving reliable results when testing grout for construction. According to ASTM C1019, the standard test method for sampling and testing grout, it is essential to obtain grout samples from the middle third of the batch, after any slump adjustments are made. This ensures that the grout sample accurately represents the material being used in the wall. Before molding test specimens, the grout sample should be thoroughly remixed with a sample trimmer, shovel or trowel to achieve uniform consistency and representative grout properties.
For laboratory grout compression testing, grout specimens are formed using molds made from concrete masonry units (CMUs) that closely match the absorption and moisture content characteristics of the masonry units used in the actual construction. This step is critical for producing test specimens that reflect real-world performance. The molds should be placed on a stable, level surface, free from vibration, and left undisturbed for 24 to 48 hours to allow the grout to set properly. During this time, it is important to measure and record the specimen width, height, and any out-of-plumb conditions. The average width is then used to calculate the cross-sectional area, which is necessary for determining compressive strength.
An alternative to the traditional method is the Grout Sample Box (GSB). The GSB has four sections and slotted corrugation to retain moisture effectively, simulating the absorption rates of CMUs. This design produces consistent and identical prism samples, perfect for quality control purposes and to get comparable compressive strength values in laboratory grout compression testing.
By following the test method and procedures in ASTM C1019, contractors and testing agencies can ensure that ASTM grout specimens are sampled, molded, cured and tested according to ASTM International standards. This allows for selecting the right grout proportions, performing quality control tests and determining grout strength and moisture content characteristics. Proper preparation, sampling, and monitoring of grout placement is key to getting accurate test results and maintaining the quality and consistency of grout used in masonry.
FAQs
Is Prism grout worth it?
Yes with its strong formula and better stain resistance.
What size is a grout prism?
A Grout Prism is 3-1/2” square by 7-3/4” high. It’s made of thin corrugated cardboard and has a slotted surface to allow moisture to pass through the block.
Do I need to seal prism grout?
The manufacturer states that Prism Ultimate Performance Grout does not require sealing. However, sealing is recommended for best results.
What is the sample size for grout?
Minimum sample size of 12 ft3 for slump and compressive strength testing. Two or more grout portions should be taken at regular interval during grout discharge and then combined to form the bulk sample. Properly sampled grout is crucial to get accurate test results.
What is the purpose of grout prisms?
Grout prisms are used to determine the right proportion of a grout mix and to check its consistency throughout the construction process. This is necessary to ensure the grout mix is of high quality and will not cause problem during construction.
