Experimental Study On Mechanical Properties And Frost Resistance Of Cement Stabilized Sandstone Gravel Mixture

After the 19 th CPC national congress,China embarked on a new journey to build a strong transportation country,and the number of highway construction continued to grow.Under this background,cement stabilized gravel is widely used in pavement base or subbase because of its excellent pavement performance and low cost.Accordingly,each district has great demand of stone material.Recently,many stone factories closed because of environmental problems,which makes the national stone market in short supply.Therefore,this paper attempts to use the abundant sandstone resources of Shaanxi province as the graded broken stone in the cement stabilized gravel mixture to alleviate the shortage of local high-quality road building stones.The sandstone along the highway project under construction in Shaanxi province was experimented in this paper to analyze its physical properties,mechanical properties and applicability.This paper also did some experiments to find the key influence factors of the cement stabilized sandstone gravel mixture's mechanical properties and antifreeze performance.The main conclusions of this paper are as follows: Firstly,the sampled sandstone in this paper was mined from northern Shaanxi,and the main mineral composition is arkose and quartz sandstone,which has poor physical and mechanical properties compared with limestone.While the performance index of the sandstone gravel can meet the standard requirements.Secondly,the 7-day unconfined compressive strength representative value of the cement stabilized gravel mixture specimens designed in this paper meets the requirements of the code.When the cement content increases to 4.0%,each 7-day unconfined compressive strength representative value of cement stabilized gravel mixture specimens is greater than 3.5MPa.Thirdly,the curing age and the cement content of cement stabilized sandstone gravel mixture have a great influence on strength,stiffness,water resistance and frost resistance.When the cement content is constant,the strength and the curing age of cement stabilized sandstone gravel mixture are logarithmic function,and the strength is basically formed at the curing age of 90 days.Cement content can effectively improve the strength and stiffness of cement stabilized sandstone gravel mixture.If the cement content increases more than 4.0%,the strength and stiffness of specimens are significantly improved.It is suggested that the cement content of cement stabilized gravel mixture should be greater than 4.0%.The curing age of the specimens and cement content on cement stabilized sandstone gravel mixture also have a great influence on water resistance,appropriate cement can effectively improve the water resistance of cement stabilized sandstone gravel mixture.When the curing age of the cement stabilized sandstone gravel mixture is over 60 days,the softening coefficient of each cement stabilized sandstone gravel mixture specimen growth rate decreases,and the strength is close to the intensity of the unsaturated specimens.The softening coefficient of the sample with cement content of 4.0% is greater than 0.75.With the same cement content,the strength of the specimens before freezing-thawing and that of the comparison group have the same trend as the curing age increases.When the curing age of cement stabilized gravel mixture reaches 90 days,it has a certain frost resistance.The cement content can effectively improve the frost resistance of cement stabilized sandstone gravel mixture.When the cement content is above 4.0%,the frost resistance is significantly improved.