Astm C642 Density Absorption Voids In Hardened Concrete (2024)

The sample is placed in a ventilated oven at 110 ± 5°C (230 ± 9°F) for at least 24 hours, or until it stops losing weight. This is the – the skeleton of the concrete, stripped of all free water. Step 2: The Flood (Saturation) Now comes the counter-intuitive part. To find the voids, you must fill them. The dry sample is placed in a water bath at 21 ± 2°C (70 ± 4°F) for at least 48 hours. But that’s not enough to reach full saturation. Air gets trapped in fine pores.

Note: Values >20% permeable voids generally indicate poor-quality concrete or a mix design error. astm c642 density absorption voids in hardened concrete

[ Voids = [(B-A)/(B-C)] \times 100 ] What it means: This is the headline metric. It includes all voids that can be filled with water under boiling conditions—capillary pores, entrained air bubbles, and even small cracks. For good-quality structural concrete, this value is often between 12% and 18%. For the failed bridge deck? It was 24%. The Plot Twist: What Boiling Reveals That Soaking Cannot The junior engineer asked a smart question: "Why boil? Why not just soak it for a week?" The sample is placed in a ventilated oven

The technician then weighs the sample submerged in water (using a wire suspending it from the scale). This gives the . Then, they remove it, gently blot it with a damp towel, and weigh it again in air. This is the Saturated Surface-Dry Mass (SSD) (B) . Step 3: The Arithmetic (Calculations) With three numbers—A (dry), B (SSD), and C (submerged)—the hidden geography of the concrete is revealed. To find the voids, you must fill them