A STUDY ON THE RELATIONSHIP BETWEEN SMECTITE CONTENT AND SWELL POTENTIAL INDICES

surface and sub-surface samples of expansive soils was collected in the Handan-Yongnian area, Nanyang district, Pingdingshan area along the middle line of the Project of Diverting Water from South to North and in Xiangfan area and Zhongxiang district of Jingmeng City. Clay mineral composition and smectite content were determined by using XRD and dye absorption methods. Meanwhile,such indices as liquid limit, plastic limit, specific surface, clay particles and colloid particles, free swell ratio were quantitatively measured. Study on smectite content and the indices for discrimination swell potential indicates that smectite content is a principal factor controlling the swell potential. Of course, the measurement errors, mainly the error in smectite content, are also the second factors influencing swell potential gradation. The swell potential graded by using Seeds method is higher by 1 to 2 levers than that by using the suggested standard in the paper. The relationship between smectite content and indices is linear, logarithmic or exponential and provides a basis for expansive soil remote sensing in relation with the diagnostic absorption features of clay minerals.