Methods of Testing Compressive Strength of Masonry

According to the Building Code Requirements and Specification for Masonry Structure (ACI 530.1-11) and its quality assurance programme, certification of compliance, testing compressive strength of masonry before construction and for every 464.5 m2 of masonry work during construction is necessary. The unit strength method and the masonry prism method are two methods for specifying compressive strength of clay and concrete masonry. ACI 530.1-11 specifies certain testing procedures.

One of the two ways is specified by engineers or architects. The contractor is allowed to choose the method of evaluating masonry compressive strength if the method of testing has not been defined.

Methods of Testing Compressive Strength of Masonry

The prism testing method is more expensive than the unit strength approach due to costs associated with creating prisms and conducting laboratory tests. The conclusions of the unit strength approach, however, are more cautious than those of the prism strength method. The following are the methods for determining the compressive strength of masonry: Method of calculating unit strength Method of the prism test Masonry Compressive Strength Testing Method Using Unit Strength Masonry units must be tested before and during construction using the unit strength method to ensure their adequate strength. The stipulated compressive strength of masonry (f’m) is determined by the mortar as well as the compressive strength of the masonry units.The ASTM requirements for both clay and concrete masonry units should be followed.

ASTM C 62-05: standard specification for building bricks (solid masonry units made from clay or shale), ASTM C 216-05a: standard specification for facing brick (solid masonry units made from clay or shale), and ASTM C 652-05: standard specification for hollow brick are all applicable ASTM specifications for clay masonry units (hollow masonry units made from clay or shale). The sampling and testing of clay masonry samples must follow the Test Methods for Sampling and Testing Brick and Structural Clay Tile.Similarly, concrete masonry units should follow ASTM C55-03: Specification for Concrete Brick and ASTM C90-06: Specification for Load Bearing Concrete Masonry Units for sampling and testing, as well as ASTM C 55-03a or ASTM C 90-06 for sampling and testing.

Prism Method of Testing Compressive Strength of Masonry

In the case of grouted masonry, the grout used for concrete and clay masonry units shall meet ASTM C 476 standards, and the grout compressive strength should be equal to or more than the masonry compressive strength and no less than 13.79 MPa. In addition, the thickness of the bed joint in both concrete and clay brickwork must be equal to or less than 15.87 mm.Masonry Compressive Strength Testing Using a Prism Masonry prisms, as shown in Figures 1 and 2, are an assemblage of masonry units, mortar, and grout (if applicable) that are constructed and tested for compressive strength in accordance with ASTM C 1314-03b: Standard Test Method for Constructing and Testing Masonry Prisms, which is used to determine compliance with specified masonry compressive strength.

The ASTM C 1314-03b standard covers masonry prism construction, testing, and procedures for measuring the compressive strength of masonry (f’m). This test method can determine whether or not the masonry materials employed generate masonry with the required compressive strength. The masonry units used to make masonry prisms are an example of the types of units that will be employed in future construction. Furthermore, the prism test method necessitates the construction of at least three prisms, all of which must be made of the same material. To construct prisms, at least two masonry pieces should be used, and they should be tested at the same time using a predetermined technique. The aspect ratio, or the ratio of the prisms’ height to their smallest lateral dimension (hp/(tp)), should be between 1.3 and 1.5.

Solid Unit Prism

All masonry units must be laid in a stack bond in stretcher position, oriented as in the appropriate construction, and properly mortared. The length and width of a masonry prism are the same as the length and width of a masonry unit. Not only does the mortar and joint thickness need to be representative of the construction, but also the unit positioning and aligning method while prisms are being prepared; the prisms may be constructed as solid or hollow ungrouted or solid or hollow grouted depending on the real situation of the structure. Grouting, consolidation, and reconsolidation must all follow the same technique as the related construction. The grouting of two series of prisms is necessary; one set is grouted and the other is not.

When it comes to grouting prisms solidly, the time frame should be no less than twenty-four hours and no more than forty-eight hours. Furthermore, they must be stored in airtight bags and not disturbed for at least 48 hours. After that, the prisms must be kept at 24 oC.Prism tests are conducted after 28 days or any other time period indicated, however the prisms must be removed from their airtight backs two days prior to the start of the test.

Both the effective design of new earth structures and the rehabilitation of existing structures necessitate a reliable assessment of earth material compressive strength. However, the optimum approach for correctly measuring the compressive strength of earth bricks is still up for debate. The cube specimen, half-block stacked specimen, and full-size block specimen are used to evaluate the compressive strength of moulded adobe and rammed adobe, respectively, while taking into account the influence of the specimen preparation procedure, loading direction, capping, and other parameters. A compressive strength test method for earth blocks was developed by comparing and analysing the stress state, failure mode, and compressive strength of the specimen under various test methods.

Penetration Resistance Test

It’s critical for project managers to examine the influence each methodology will have on their timeline when selecting a method for monitoring concrete compressive strength. While some testing can be done on-site, others necessitate additional time for third-party facilities to deliver strength data. Project managers’ decisions are influenced by more than just time. The precision of the testing process is equally vital, as it has a direct impact on the concrete structure’s quality. The use of field-cured cylinders is the most popular approach for monitoring the strength of in-situ concrete. Since the early nineteenth century, this practise has remained mostly constant. These samples are cast and cured in accordance with ASTM C31, and their compressive strength is evaluated by a third party.

Since this testing procedure was first launched, there have been numerous advancements to speed up the curing process. Heating blankets, additives, and vapour retarders are all examples of this. Contractors, on the other hand, continue to wait three days after placement before testing for strength, despite the fact that their targets are frequently met far sooner. Despite this, many project managers prefer to continue testing in this manner because “that’s how it’s always been done.” That isn’t to say that this method is the quickest or most accurate for determining the strength of all placements. Aside from cylinder break tests, there are a variety of other methods that can be performed. When it comes to strength testing, there are seven main ways to examine.

The fundamental idea behind this test is to pull the concrete using a metal rod that has been cast in place or inserted after the concrete has been poured. Compressive strength is connected to the pulled conical shape, as well as the force necessary to pull the concrete. Pros: It’s simple to use and can be done on both new and ancient structures.Cons: The concrete will be crushed or damaged during this test. For accurate results, a significant number of test samples from various areas on the slab are required.

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