Research On The Optimization Of Cement Reinforcing Agent And Its Application In High-titanium Sla

High titanium blast furnace slag(referred to as high titanium slag)is a solid waste generated during the ironmaking process of blast furnaces,which contains a large amount of titanium calcium carbonate.As of the end of 2022,the accumulated stock of high titanium slag in the Panxi region of China has exceeded 100 million tons,and the production is still increasing at an annual rate of 7 million tons.The massive storage of high titanium slag wastes land and slag resources.There are two types of slag: air-cooled and water quenched.In ordinary slag,the former has no cementitious properties,while the latter has a glass body that can be stimulated by certain means to achieve its cementitious properties.Compared with ordinary slag containing more silicates,high titanium water quenched slag contains Ti O 2 that combines with calcium oxide in high titanium slag during rapid cooling to generate stable Ca Ti O3 mineral phase,which poses great difficulties in stimulating the activity of high titanium slag and m aking it a slag admixture.On the one hand,this paper analyzes the influence of r einforcing agents on the mechanical properties of cement,analyzes the changes in cement physical indicators,combined water content,and hydration products caused by the add ition of reinforcing agents to cement,and selects the reinforcing agent with bett er enhancing effect on the mechanical properties of cement to obtain a composite reinforcing agent.It explores the influence of composite reinforcing agents on the mechanica l properties and activity index of high titanium slag admixtures.On the other han d,we also explored the effect of activators on the activity of high titanium slag,and ultimately achieved a high titanium slag activity index of over 70% through the synerg istic effect of activators such as quicklime and composite reinforcing agents.The following conclusions were obtained during the specific experimental process:(1)The optimum content of metakaolin in mineral reinforcements is 4%,which can increase the 28 d compressive strength of cement mortar by 8.4 MPa;The optimal thermal activation temperature of fluorosilicone slag is 350 ℃,and the optimal dosage is 0.8%,which can increase the compressive strength of cement mortar by 9.4MPa after 28 days.Most of the mineral reinforcing agents studied in this paper will cause a decrease in cement fluidity.(2)The optimal dosage of naphthalene sulfonate formaldehyde condensate in surfactants is 0.08%,which can increase the compressive strength of cement mortar by 3.4 MPa after 28 days;The optimal dosage of sulfonated melamine formaldehyde resin(melamine resin)is 0.06%,which can increase the compressive strength of cement mortar by 4.7 MPa after 28 days.The several surfactants studied in this paper can all improve the flowability of cement mortar.(3)The optimal ratio of the composite rein forcement agent(CRA)is 6% of metakaolin,0.6% of fluorosilicone slag,0.06% of FDN,and 0.04% of melamine resin.It is verified that the composite reinforcement agent can i ncrease the 28 d flexural strength and compressive strength of cement by 1.6 MPa an d 14.1 MPa,respectively,indicating that CRA can significantly improve the mechanical properties of cement.(4)The effects of both the preferred reinforcing agent and the c omposite reinforcing agent(CRA)on the physical indicators of cement,except for mechanical properties,are within the range required by the standard after the addition of cement.Through XRD and SEM analysis,it is found that the hydration products in th e cement paste with CRA are the same as those in the cement paste without strength ening agent,which are mainly Ca(OH)2,C-S-H and AFt(hydrated calcium sulphoaluminate,namely ettringite).The addition of strengthening agent to cement does not introduce new hydration products,but will increase the content of hydration products and t he compactness of the internal structure of cement paste.(5)The activity of replacing cement with 50% content of high titanium slag is only 47.0%.Using an activator to exc ite the activity of high titanium slag,quicklime has the best activation effect o n high titanium slag.A 2% content of quicklime can increase the activity of specimens prepared with 50% content of high titanium slag replacing cement by 15.3% after 28 days.(6)The combined action of CRA and activator quicklime on high titanium slag can increase the activity of high titanium slag to 71.6% after 28 days,achieving the experimental goal.At the same time,the research indicates that the synergistic effect of Ca O-CRA on high titanium slag meets the standard requirements in terms of water consumption,setting time,and stability of high titanium slag admixtures.From SEM,it can be seen that the addition of Ca O-CRA stimulates the activity of the glass body in high titanium slag,promotes the hydration of cement,and produces more hydration products.