The Influence Of Continuous Construction On The Strength Of CSG

Cement sand and gravel material(Hardfill material)is the incorporation of a small amount of cementitious materials in natural sand gravel(such as cement and water)composite material by mechanical mixing form,can be regarded as dry lean concrete material,is a kind of new material dam.The mechanical properties of the material are between the rockfill and concrete,but higher than the strength of the concrete.The cementitious material of the sand and gravel material is small,the hydration heat is small,and the temperature effect is low.Compared with other types of dam,with safety and good economy,has also been called the "Green Dam dam",cement sand and gravel dam materials can be used construction technology similar to RCC,can save construction cost and shorten construction period,competitive and good application prospect in dam construction.On the basis of summarizing the domestic and foreign research results,this paper mainly studies the influence factors of the continuous strength of the sand and gravel in the experiment:(1)through the coagulation time test of the roller compacted concrete mixture,the initial setting time of the gel sand gravel is 360 min,and the final setting time is 1810 min.When the dosage of sodium gluconate is less than 1%,the final setting time interval is almost unchanged.When the dosage is greater than 1%,it has little effect on the initial setting time(2)by sodium gluconate mixed with different dosage as retarder,the admixture of 2% were extended by 20 hours and 37.5 hours,mixing amount of gluconic acid sodium in 0.1% when the compressive strength of cement sand and gravel has improved,with the increase of sodium gluconate,cement sand and gravel early compressive strength decreased significantly,and the later compressive strength also decreased to a certain degree,get the suitable dosage of sodium gluconate for dosage of cement 0.1%-0.8%.When the dosage of sodium gluconate was less than 0.8%,the compressive strength of 3d and 7d was affected,but the compressive strength of 28 d could be restored.When the dosage was greater than 0.8%,the compressive strength of 28 d was lower than that of control group.(3)obtained under stress in the same dynamic simulation of discontinuous construction,the initial compressive strength after 8 hours in 28 days is 89% in the control group,after the final setting of the compressive strength at 8 hours and 28 days is 71% in the control group,and in the end after 16 hours,the 28 day compressive strength is the control group 99%,should try to avoid the initial setting after 8 to 8 hours after the final setting of the 24 hour interval in the construction process.If the construction conditions are not allowed,at this time the need for the joint surface for cold treatment.(4)for the continuous construction of dynamic stress attenuation,in the initial 8 hours,the 28 day compressive strength accounted for 84% in the control group,the corresponding depth and stress value of 2.8 meters and 20.1kPa,in the process of construction,paving thickness should be at least 4.4 meters in the initial 4 hours.Combined with the construction schedule can be used to block the construction process,and continue the construction in 16 hours after the initial setting,the combination of surface cold joint treatment,can avoid the construction of dynamic load on the lower layer of material damage.