HIGH PRODUCTIVITY CONTINUOUS CONCRETE MIXING SYSTEM Tek Raj Gyawali*, Kazuie Yamada**, Matabee K. Maeda*** *Dr. Eng., Research Engineer, Maeda Corp., Japan gyawali@jcity.maeda.co.jp **Dr. Eng., Director, Maeda Corp., Japan kyamada@jcity.maeda.co.jp ***Dr. Eng., Chairman ,Maeda Corp., Japan maedak@jcity.maeda.co.jp Abstract: Newly developed continuous M-Y mixer has number of mixing units connected in series. When using it in the horizontal way, it fully complies the 2 n mixing theory of kneading and lapping mechanism. When using it in the vertical way, mixing work can be done under gravity force only, with the new modified mechanism of inter-particle collision and impact. The vertical set-up of M-Y mixer is renamed as Energy Saving Gravity (ESG) mixer to represent its mixing characteristic under gravity force only. A newly developed High Productivity Continuous Mixing System (new mixing system) is composed of ESG mixer, continuous conveying systems and real time monitoring system. This paper describes about this new mixing system and its practicability for concrete production work in dam project. Keywords: 2 n mixing theory, kneading and lapping, M-Y mixer, inter-particle collision and impact, ESG mixer, new mixing system, real time monitoring system. 1. DEVELOPMENT OF NEW 2 n MIXING THEORY AND ITS VERIFICATION The new 2 n mixing theory is mainly based on the kneading and lapping mechanism, similar to the traditional mixing method of Japanese noodles, udon. In n numbers of kneading and lapping process, 2 n layers of material are formed resulting in uniform distribution of each constituent [3]. With the development of one proto-type experimental mixer, this new mixing theory was verified as similar to that of the conventional one for the quality of mixed concrete materials both in their fresh and hardened state. Its merit was also marked out for mixing those viscous, light and lean materials, which were noticed difficult to mix in the conventional mixers [4]. 2. DEVELOPMENT OF M-Y MIXER AND ITS MIXING EFFICIENCY A continuous mixer, M-Y mixer (previously named as MY-BOX), was developed for the practicability of 2 n mixing theory [5]. The application of 2 n mixing theory in horizontal set-up of M-Y mixer is shown in figure 1. As shown in the figure, one unit of M-Y mixer has two vertical inlets and two horizontal outlets. As from inlet to out let vertical dimension gradually decreases and the horizontal one increases with same proportion resulting in similar cross-section area through out. When material is sent with pressure, inner structure of M-Y mixer makes it to be kneaded while passing through each unit. As passing from inlet to outlet, material compresses vertically and stretches towards horizontal direction. In this way, material entering into two vertical inlets of first unit becomes horizontally two layers in its outlet. Similarly, Materials passing through second unit form four layers, and eight layers from third unit. In this way, materials form 2 n layers when passing through n th unit fulfilling the basic principle of 2 n mixing theory. Continuous mixing was possible in the horizontal set-up of M-Y mixer with the process of kneading and lapping by charging the materials in the continuous way using external pressure. It showed the merit over conventional method for mixing viscous and lightweight materials [5]. But, it was failed to mix materials of large size particles. 076_MA3.doc- 1 –