For sampling from a paver hopper, which procedure is correct?

• A. Remove the upper 0.15 to 0.2 m of material in the center of the hopper (avoid sampling within 1.5 ft of hopper sides)
• B. Remove the upper 0.15 to 0.2 m from the top and sample from the sides
• C. Remove the upper 0.15 to 0.2 m in the center, avoid sampling within 1.5 ft of hopper sides, and trim the front of the sampling area to form a 0.2 to 0.3 m vertical face
• D. Remove the bottom 0.2 m of material and sample from the bottom edge

Answer: (C)

Sampling from a paver hopper must give you a representative cross-section of the material, not the surface or the walls. To achieve this, you remove a shallow layer from the center so you’re not sampling the very top surface, which can be segregated or disturbed, and you keep away from the hopper sides where the material can cling to walls or be influenced by wall effects. Then you trim the front of the sampling area to create a clean, vertical face about 0.2 to 0.3 meters high. This exposed vertical face lets you take a sample that reflects the material across the hopper width rather than a biased slice from the edge or bottom. Sampling from the sides or from the bottom edge would bias the results due to wall effects or differential settling, so they’re not appropriate. The combination of center removal, top-layer discard, and a vertical-faced front produces a representative sample of the mix in the hopper.