Mineralogical Changes Of Four Clay Minerals Under The Excitation Of Alkali And Sulfate

The scale of China's infrastructure construction has ranked first in the world for many years.Infrastructure construction needs to be carried out in areas with complex geological environment(such as soft soil areas),so how to strengthen soft soil and greatly improve its carrying capacity has been an important research topic.In the process of concrete manufacturing,clay mineral entering into the system will have a negatively affect the performance of concrete.Some clay minerals have the activity of hydration and hardening.In the concrete system,the hydration and hardening reaction of clay minerals can not only reduce the instability of dry and wet changes of clay minerals,but also affect the clay minerals under the conditions of concrete,but,previous scholars have not systematically studied specific minerals..The research of the reaction of clay minerals under the conditions of concrete is raises urgent needs.Previous studies have found that clay minerals have pozzolanic activity and potential hydraulic activity,so how to stimulate the activity of clay minerals is an important topic in the utilization of clay minerals.In this project,Kaolinite,Montmorillonite,Illite and Chlorite,are the research objects.Using calcium hydroxide and Gypsum to make alkali-sulfate composite activated system.The clay minerals(87%),calcium hydroxide(10%)and gypsum(7%)are used to make cementitious materials.And testing sample's mechanical properties,find the mineralogical changes of clay minerals.The curing temperature and polycarboxylate superplasticizers were the experimental variables.The curing temperature was set at 25 ? and 55 ?,and the additive amount of the polycarboxylate superplasticizers in control group is 0.3% of the total quality of the cementitious material.Through the cure of 3~28 days.At 25 ?,the 28 day compressive strength of Kaolinite sample is 1.09 MPa.Montmorillonite sample is 0.94 MPa.Illite sample is 0.26 MPa.At 55 ?,the 28 day compressive strength of Kaolinite sample is 4.93 MPa.Montmorillonite sample is 4.93 MPa.Illite sample is1.43 MPa.After adding polycarboxylate superplasticizers.At 25 ?,the 28 day compressive strength of Kaolinite sample is 1.56 MPa.Montmorillonite sample is 1.38 MPa.Illite sample is 0.41 MPa.At 55 ?,the 28 day compressive strength of Kaolinite sample is 5.53 MPa.Montmorillonite sample is 5.33 MPa.Illite sample is 0.92 MPa.However,Chlorite samples are not hardened under the above conditions.The products produced by the hydration reaction mainly include Ettringite,calcium aluminate hydrate,Crystalline zeolite phase and calcium silicate hydrate.Increasing the curing temperature can effectively improve the reaction speed,but the effect on chlorite is not obvious.Kaolinite,Montmorillonite and Chlorite will greatly reduce the polycarboxylate superplasticizers performance of water-reducing agent,while Illite does not affect the polycarboxylate superplasticizers.The polycarboxylate superplasticizers can slightly improve the early reaction speed,but it will not affect the reaction.The polycarboxylate superplasticizers had no obvious effect on the Chlorite group.