Astm C642 Density Absorption Voids In Hardened Concrete //free\\ Now

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. astm c642 density absorption voids in hardened concrete

[ 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. | Property | Typical Value | | :---

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. This is the Saturated Surface-Dry Mass (SSD) (B)

Because time is not the same as energy. A sample soaked at room temperature for a month will still have trapped air in pores smaller than 0.1 microns. Boiling forces water into those nano-pores. ASTM C642 is deliberately aggressive. It measures permeable voids—the voids that actually connect to the surface and can transport water.

[ 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.