ABSTRACT
This method is more satisfactory than volume batching in producing good concrete. There are a number of machines available incorporating a weighing hopper. Care must be taken to see that the machine is set level and that the hopper is carefully loaded, uneven loading can give an incorrect reading of the weight. The plant should be checked for accuracy when beginning a job, whenever the machine is moved and at least once a week. First check that the indicator reads zero when the hopper is empty, then load with a known weight, e.g. three 50kg bags of cement, which weigh approximately 152kg (including the weight of the bags) and check that this weight is indicated. The machine should be accurate to within ±2% of the indicated load.
