| Property | Typical Value | | :--- | :--- | | Dry Density | 125 – 155 lb/ft³ (2000 – 2480 kg/m³) | | Absorption | 4 – 8% | | Permeable Voids | 12 – 18% |
So, the technician brings out the hot plate. The sample is boiled in distilled water for . Boiling reduces the surface tension of the water and expands the air in the pores, driving it out. After boiling, the sample cools overnight while still submerged. 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?" | Property | Typical Value | | :---
[ Absorption = [(B-A)/A] \times 100 ] What it means: The concrete’s appetite for water. High absorption (typically >8% for normal concrete) suggests a permeable matrix vulnerable to freeze-thaw damage and chemical attack. After boiling, the sample cools overnight while still
[ D_dry = [A / (B-C)] \times \rho_water ] What it means: The mass of solid concrete per unit volume, including pores. A low dry density might indicate lightweight aggregate or excessive voids.