HKCC has recently stepped up efforts to control the quality of crushed rock fines by carrying out Methylene Test. The test, developed by our Technical department, is based on the BS EN: 933 Standard, using the methylene blue absorption theory to measure clay content of stone fines. The test results which set up a solid technical foundation enable us to closely monitor the quality of crushed rock fines and take necessary actions accordingly to maintain and improve product quality.