The influence of the process of mechanical activation in electromagnetic mill on the properties of fly ash are shown. The effect of ultrafine fly ash and chemical admixtures of polyfunctional action on the properties of cementitious materials was investigated. It was observed that combination of such complex chemical admixtures and ultrafine fly ash provides the reaching of technological, technical and economi- cal effects in сoncretes. The using of fly ash ultrafine particles gives the possibility of manipulation and control of properties of cementitious materials and design of High Performance Concretes new generation on their base.