3D Concrete Testing

Acceptance Criteria for 3D Automated Construction Technology for 3D Concrete Walls

Test criteria describes a typical test plan for evaluation of 3D printed concrete wall performance. The criteria covers the ASTM methods described below and modifications to the methods that specifically apply to 3D printed concrete. Other test methods are also described, and may be required, depending on the product beign tested.

Compressive Strength of Cylinderical Concrete Specimens

Molded or cored concrete specimens are tested in compression and the strength is reported on a pounds/square inch basis.

Compressive Strength of Hydraulic Cement Mortars Using 2″ Cube Specimens

Cube specimens are cast and three are tested at each of 1, 3, 7, and 28 days of curing. Samples are cured for the first 24 hours in a standard moist room, and all subsequent days in saturated lime water.

Slump of Hydraulic Cement Concrete

Performed on freshly cast material only. Wet concrete is consolidated in a calibrated “slump cone”. The cone is removed, and the consistency (slump) of the material is determined by measuring the change in height of the cone of concrete.

Length Change of Hardened Hydraulic-Cement Mortar and Concrete

Mortar or concrete is cast into beams and cured per ASTM C157 procedures. The lengths of the beams are measured, and the beams are allowed to cure in standard conditions (either lime water or laboratory air) for a period of up to 64 weeks. Intermetent readings are taken to determine the length change of the material.

Time of Setting of Concrete Mixtures by Penetration Resistance

Performed on freshly cast material only. The coarse material in fresh concrete is removed, with the remaining material collected in an appropriate container. Material is allowed to cure, and is periodically penetrated with a calibrated concrete penetrometer. A curve of penetration resistance over time is used to calculate initial and final setting times of the material.

Resistance of Concrete Beams to Rapid Freezing and Thawing.

Concrete prisms are exposed to 300 cycles of rapid freezing and thawing. The fundamental transverse frequency is determined at 30 cycle intervals, and this is used to determine the durability factor rating (out of 100).

Slump Flow of Self-Consolidating Concrete

Performed on freshly cast material only. Wet concrete is consolidated in a calibrated “slump cone” in either an uprigth (Procedure A) or inverted (Procedure B) manner. The mold is raised and the diameters of the resulting slumped concrete are measured at two opposite locations, and the slump flow is calculated.

Conducting Strength Tests of Panels for Building Construction

Test method describes various test orientations and loading methods for conducting standard strength tests on walls. Orientations include compressive load, tensile load, transverse load, concentrated load, impace load, and racking load.

Flexural Bond Strength of Masonry

A stack of masonry is assembled that is representative of the material being tested, and assembled per ASTM E518 instructions. The stack is then tested in either a third-point or uniform loading apparatus and loaded to faillure. The flexural bond strength is reported based on the loads attained and the specimen dimensions.

Diagonal Tension (Shear) in Masonry Assemblages

A masonry assemblage is assembled that has an area of 4’x4′. The assemblage is appropriately attached to the shear load test frame and two opposite corners are loaded in compression. Shear stress is reported based on the loads attained and the specimen dimensions. Optionally, shear strain may be reported by instrumenting the assemblage with length measuring devices.