This research reports new technology to mixing RHA and CaO with the Ca/Si molar ratio of , in order to synthesize calcium silicate hydrate (CSH) such as tobermorite (C5S6H5) and xonotlite (C6S6H) as environmental materials. The advantage of our study is to utilize the Vietnam RHA and to reduce the environmental impacts by using hydrothermal treatment technique. | Tạp chí Khoa học công nghệ và Thực phẩm 12 (1) (2017) 67-72 SYNTHESIS OF CALCIUM SILICATE HYDRATE (CSH) FROM VIETNAM RICE HUSH Pham Trung Kien1*, Phan Viet Hoang1, Huynh Dai Phu1, Nguyen Van Tam2, Ngo Vo Ke Thanh2, Nguyen Hoc Thang3, Hirofumi Hinode4 1 Ho Chi Minh City University of Technology (HCMUT) 2 Research Laboratories Center Saigon Hi-Tech Park 3 Ho Chi Minh City University of Food Industry (HUFI), 4 Tokyo Institute of Technology * Email: phamtrungkien@ Received: 25 June 2017; Accepted for publication: 12 September 2017 ABSTRACT Vietnam is an agricultural country, which produces lot of rice and its by product is rice husk ash (RHA). The RHA is considered as waste in agriculture, and treated by burn in the open air. This process causes air pollution, thus attracted Vietnamese researchers to find alternative method to reduce the impact of rice husk ash on environment. The research group in Department of Ceramic Materials aims to reuse rice husk ash as source of silica (SiO2). It needs to emphasize that the main content of rice husk ash is silica. This research reports new technology to mixing RHA and CaO with the Ca/Si molar ratio of , in order to synthesize calcium silicate hydrate (CSH) such as tobermorite (C5S6H5) and xonotlite (C6S6H) as environmental materials. The advantage of our study is to utilize the Vietnam RHA and to reduce the environmental impacts by using hydrothermal treatment technique. Key words: Calcium silicate hydrate, rice hush ash, hydrothermal treatment, ceramic. 1. INTRODUCTION Vietnam is an agricultural country, which produces lot of rice and its by product is rice husk ash (RHA). The RHA is considered as waste in agriculture, and treated by burn in the open air. This process causes air pollution, thus attracted researchers to find alternative method to reduce the impact of rice husk ash on environment [1-3]. The research group in Department of Ceramic Materials aims to reuse rice husk ash as source of Silica (SiO2)