Lab-grade sand testing — full sieve analysis, wet sieving for silt content, moisture determination in a calibrated oven — gives the most reliable numbers, but it isn't practical to run before every single truckload rolls onto a site. What's practical is a short set of field tests that can be done with basic equipment in under an hour, catching the deliveries that are clearly unsuitable and flagging the borderline ones for proper lab verification before they go into a mix. None of these field tests replace IS-standard lab methods for contractual or dispute purposes — they're a screening layer, and knowing the difference matters as much as knowing the tests themselves.