The mix design of cement stabilized layer should be carried out in the laboratory first to determine the cement content and the proportion of coarse and fine aggregate, and at the same time determine the maximum dry density, optimum water content and 7-day unconfined compressive strength. Construction can be done manually by grader and paver. Before the initial setting of cement, use a roller to press it to the designed compactness. After the completion of construction, water should be sprayed to maintain the water-stable layer. Because the range of soil that cement can stabilize is quite wide, and the more cement is used, the higher the strength of cement stabilized soil mixture is. Therefore, the strength of cement stabilized soil can be adjusted in a wide range to meet the strength requirements of different grades of roads and different pavement structure layers (base or subbase). For example, the unconfined compressive strength of cement stabilized soil can be as low as 1MPa and as high as10 MPa (at 7d age) until it reaches the strength of cement concrete. Therefore, in terms of strength alone, cement stabilized soil can be used as the base of various grades of road pavement. However, after considering the factors such as dry shrinkage, wet shrinkage and erosion resistance of different cement stabilized soils, the most suitable materials in technology and economy should be selected for different grades of road pavement and different pavement structure layers. In the current Technical Specification for Construction of Highway Pavement Base (JGJ 034-2000), the following basic requirements are put forward for cement stabilized soil pavement base: 1, cement stabilized soil can be applied to the base and subbase of various traffic roads, but cement soil should not be used as the base of high-grade asphalt pavement, but only as the subbase. Cement-soil should not be used as the base under the cement concrete slab in expressway and the first-class highway. 2. When using cement stabilized soil as the base, the dosage of cement should be controlled within 6%. When necessary, the aggregate gradation should be improved first, and then stabilized with cement. 3. The lowest temperature during the construction of cement stabilized layer should be above 50C, and-3 ~-50 C should be completed half a month to one month before the first heavy freezing. 4. During the construction in rainy season, special attention should be paid to the weather change to prevent cement and mixture from being rained. Design method of mixture ratio composition: 1. In order to prepare the same soil sample, more than five kinds of cement stabilized mixtures with different cement dosages should be prepared. 2. In order to determine the optimum water content and maximum dry density of various mixtures, at least three compaction tests should be carried out for mixtures with different cement dosages, namely, minimum dosage, intermediate dosage and maximum dosage. 3. According to the degree of compaction planned on the construction site, calculate the dry density of specimens with different cement content. 4. When preparing test pieces according to the optimum water content and calculated dry density for strength test, the number of test pieces used for parallel test should meet the requirements of 6 fine-grained soils, 9 medium-grained soils and 13 coarse-grained soils. If the deviation coefficient of the test results is greater than the specified value, the test should be repeated and the reasons should be found out to solve it. 5. Keep the specimen at the specified temperature for 6d, soak it for 65438±0d, then conduct unconfined compressive strength test, and calculate the average value and deviation coefficient of the compressive strength test results. The specified temperature for specimen curing in frozen area is 20 2℃, and that in non-frozen area is 25 2℃. 6. On roads with different traffic types, the 7-immersion compressive strength of cement stabilized soil should meet the following requirements: the standard surface course of cement stabilized soil is the second grade of highway and the first grade of highway below the second grade, and the expressway base (MPa) is 2.5 ~ 3.03.0 ~ 5.0 subbase (MPa) is1.5 ~ 2.0/. The average compressive strength (R) of the indoor test results of this dosage specimen shall meet the requirements of the following formula: R ≥Rd/( 1-Za Cv), where Rd is the design compressive strength; CV-coefficient of deviation (decimal) of test results ZA-coefficient varying with the assurance rate (or confidence level A) in the standard normal distribution table: expressway and the first-class highway should take the assurance rate as 95%, and at this time ZA =1.645; ; For general expressway, the guarantee rate should be 90%, that is, Za= 1.282. 8. The amount of cement actually used in the construction site should be 0.5% ~ 1.0% more than that determined by the indoor test. The key factors affecting the strength of cement stabilized layer mixture are 1 and curing temperature. Curing temperature has obvious influence on the strength of cement stabilized soil. The higher the curing temperature, the higher the strength of cement stabilized soil. 2. Influence of delay time 3. The so-called delay time means the time from mixing with water to the end of rolling. The delay time has obvious influence on the strength and dry density of cement stabilized soil mixture. The longer the delay time, the greater the loss of strength and dry density of the mixture.