ACI MFTT cheat sheet

ASTM C270 defines mortar Types M, S, N, O, and K by proportion and minimum 28-day compressive strength; Type M is the strongest and Type K the weakest.

Mortar for field tests is sampled after mixing is complete, from the mixer or discharge stream, so the sample represents the batch rather than material left on a board.

Grout is sampled per ASTM C1019 before placement, from the mixer or pump discharge, after all ingredients are mixed.

ASTM C90 covers load-bearing concrete masonry units; ASTM C216 covers facing brick; sampling must identify the lot and protect specimens from moisture change.

Mortar proportions are specified by volume of cementitious materials and sand; water is added to achieve the required consistency, not a fixed batch volume.

Grout is a high-slump cementitious mixture with aggregate and water; coarse grout contains coarse aggregate, while fine grout does not.

Samples must be labeled with project, location, batch or mixer, date, and test method before transport or storage.

Unit and mortar samples are selected to represent the materials actually used; damaged or nonrepresentative specimens are not substituted silently.

Mortar consistency is measured by the flow table test in ASTM C1437; the table is dropped 25 times in 15 seconds and the spread is measured.

Flow (%) = [(spread diameter − original diameter) / original diameter] × 100, using the average of measured diameters.

Fresh mortar water content is found by drying a weighed sample to constant mass; water content compares the mass lost to the dry mass.

Field mortar compressive strength is commonly evaluated with 2-inch cube specimens molded per ASTM C780 and cured to the specified test age.

ASTM C1019 grout specimens are molded from fresh grout, consolidated to remove voids, cured, and tested in compression.

Each specimen must be marked with project, location, batch, date, and test age before initial curing begins.

Initial curing must protect specimens from moisture loss, vibration, and temperature extremes that would change strength.

Do not add water to mortar after it has begun to set; consistency adjustments are made at the mixer before placement.

ASTM C1314 governs masonry prism compressive strength; prisms are built from the same units, mortar, and grout as the masonry they represent.

A prism test set typically contains at least three prisms, and the average result is used to evaluate the masonry.

Prisms must be constructed with joint thickness, alignment, and grouting representative of the field construction being evaluated.

Prism height-to-thickness ratio affects measured strength; ASTM C1314 provides correction factors for standardizing results.

Before compression testing, prisms are capped to produce plane, parallel surfaces perpendicular to the applied load.

Prism compressive strength equals maximum load divided by the specified cross-sectional area; report individual values, average, and test age.

Prisms are cured under conditions representative of the field masonry, then capped and tested at the specified age, commonly 28 days.

Capping materials such as sulfur or gypsum must be strong enough to prevent local crushing and must bond to the prism surface.

ASTM C140 covers sampling and testing of concrete masonry units for compressive strength, absorption, and saturation coefficient.

Unit compressive strength is measured on capped units loaded perpendicular to the bed surface; strength equals maximum load divided by gross area.

Absorption (%) = [(saturated mass − oven-dry mass) / oven-dry mass] × 100 for the specified immersion period.

Saturation coefficient compares a unit's 24-hour cold-water absorption with its absorption after a longer saturation or boiling procedure.

Oven-drying temperature, drying time, and cooling time must follow the standard; incorrect conditioning biases absorption results.

Units with cracks, chips, or irregular geometry that affect load capacity or absorption are noted or excluded according to the standard.

Report individual unit values and the average; identify any specimen excluded and the reason for exclusion.

A test report must identify the project, sample location, test method, test date, specimen age, dimensions, results, and tester.

Report both raw measurements and calculated values with units; include failure mode or anomalous behavior when observed.

Field records should note batch time, mixer, materials, water additions, and any deviation from the specified test procedure.

ACI Masonry Field Testing Technician certification documents that personnel are qualified to perform specified masonry field tests.

Personnel qualifications must be current and applicable to the test being performed; certification records are retained.

Reports are signed or initialed by the tester and reviewed by the responsible supervisor or engineer as required by the contract.

Electronic records must be backed up and protected from loss or unauthorized alteration; retention follows contract or code requirements.

An unusual or nonconforming result is reported and investigated, not discarded without a recorded explanation.