Experimental Study And Mechanism Analysis Of The Effect Of Mud Content On The Performance Of Cement Stabilized Weathered Sand

There are lots of weathered sand in the Three Gorges Reservoir area of Yichang,Hubei province.Which has the advantages of convenient reclaimer,low cost of mining and large angle of internal friction.At the same time,it has the disadvantages of strength instability and large gradation variability,so it is only used as subgrade filler and is not widely used in pavement base.In this paper,the weathered sand in the Three Gorges Reservoir area of Yichang is studied.Different qualities of clay and cement are added into the weathered sand in order to study the road properties of cement stabilized sand with different mud content.Firstly,the basic characteristics of cement stabilized weathered sand were tested,and the results showed that the basic characteristics of the cement stabilized weathered sand have changed greatly with the mixture of cement and clay.The incorporation of cement reducesd its void ratio and increased the specific gravity of the soil,making the soil easier to compress,and its permeability and compressibility has also decreased,In the meanwhile,its overall stability was enhanced and its boundary moisture content was greatly improved.The proportion of cement stabilized weathered sand increases with the incorporation of clay content,due to its strong hydrophilicity and low interparticle connectivity,the permeability of stabilized soil becomes worse,while its compressibility increases,and it is difficult to be compacted.Secondly,the stability test of cement stabilized weathered sand is carried out to study its water stability and freeze stability by changing the soaking time,freezing and thawing cycle temperature and the number of freezing and thawing cycles.It is found that cement stabilized weathered sand has better water stability and frost stability;the cement content and curing age have better effect on the improvement of the stability performance,and the mixing of clay will reduce the stability of the mixture.With the soaked age growth,its unconfined compression strength decreases rapidly,then slowly rises,and then slowly decrease.With the decrease of the freezing and thawing cycle temperature,the stability of the freeze-thaw is worse.With the increase of the number of freezing and thawing cycles,the strength of the freeze-thaw cycle decreases continuously,but in the end it still has a higher strength.Finally,the change rule of unconfined compressive strength,splitting strength and compressive resilience modulus of weathered sand stabilized by cement at different curing ages is discussed.The results show that the three strength indexes of cement stabilized weathered sand are all increased with the increase of cement content,and the growth rate is faster between 3% and 6% of cement content,and the growth rate is relatively slow over6%.When clay content is about 5%,each strength index reaches the maximum value,and then there is an obvious decreasing trend.The strength increases with the growth of the curing age,and the growth rate is slower and slower.Considering the requirements of each index of the road base,this paper suggests that the best rate of the cement content is5%～6%,and the clay content is not more than 5%.In this paper,a series of studies have been carried out on the cement stabilized different mud content weathered sand.It is found that the weathered sand with different mud content can be used as the base or base of the pavement through cement stability,and the requirements of different base layers can be met by adjusting the amount of cement.The use of saving natural resources,has better promotion value.