Spread Test

The spread test for freshly mixed UHPC is determined by testing the spread value in accordance with ASTM C1437. After mixing the paste, the fresh mix is placed into a spread cone (see figure). Special care should be taken to keep the spread cone and the base plate at the same humidity level prior to testing. Due to the inherent high flowability of the paste, there is no need to compact the UHPC in the mold and no vibration is required. The spread cone is filled up to the rim and then lifted at a fixed speed. The leftover material sticking to the wall of the cone is scraped off and the material on the base plate is left to spread. After 2 min ± 5 sec has elapsed, the diameter of the spread UHPC paste is measured along two perpendicular directions and the average diameter is calculated and recorded as the spread value.

The spread should be between 175 mm (7 in) and 300 mm (12 in). Spread values outside this range indicate that the mix should be rejected.

Figure above: (a) mold used for spread test; (b) spread test results.

See below for a video showing how to conduct the spread test.