国际会议演讲稿

Freeze–thaw cycle test and damage mechanics models ofalkali-activated slag concrete＇＇＇＇T hank you for your invitation and warm hospitality.It is a privilege and honor to be invited at the United Nations to deliver a talk on “Freeze–thaw cycle test and damage mechanics models of alkali-activated slag concrete”I would like to thank Professor Cui ,for inviting me to deliver this talk .I hope that the Congress will provide the opportunity for personal exchange of scientific results, facilitate the making of new acquaintances, and strengthen personal friendships among scientists (participants) from different parts of the world.I will restrict my presentation to about 5 to 10 minutesFirst, I would like to reflect upon the International perspective on “Freeze-thaw cycle test and damage mechanics models of alkali-activated slag concrete”. Thepl entiful studies on a new green binding material—alkali-activated concrete . Second, I will attempt to highlight .The effect of freeze-thaw cycles on in concrete was studied by experiment.Third，I shall explore a possible agenda for analysis to enable understanding of the alkali-activated slag concrete.Now let's come to know the “new green binding material—alkali-activated cement”The first part is the introduction of Freeze–thaw cycle test and damage mechanics models of alkali-activated slag concrete. Now let's look at the ppt In recent years, there are plentiful studies on a new green binding material—alkali-activated cement, it can be prepared by wastes containing kaolinite (原文introduction第一句) The binding materials with three-dimensional network structure are yield by shrinking and polymerization reaction. With the arriving of low carbon economy time, international governments attach more importance to energy saving, emission reducing and cycled economics.(原文第二段)so it can be called a genuine low carbon cement.（ppt第3页）The second part is the Freeze–thaw cycle experimentation and the first subpoint I'd like to talk is the materials we can see clear that the Slag used in this study was metallurgy blast furnace slag, was supplied by Jiangxi Building Materials Plant, PR China, its specific surface is 410 m2/kg. chemical compositions of slag are listed in Table 1.（ppt第4页）NaOH and Na2SiO3 sodium silicate multiplex solution was used as alkali activator, module of sodium silicate is 3.34. Sand with fineness modulus of 2.78 was used as fine aggregate. Limestone were used as crushed rock aggregate (5–20 mm:20–40 mm = 45:55).(引用原文Materials第二段结论)The second subpoint I will say is the Mix proportion and specimen preparation , . Mix proportion and specimen preparation.Mix proportion, workability and compressive strength at 28 d of ASC are listed in Table 2. It was prepared by a single decubital axis compellent beater with content of 60 L. the samples were demoulded and curedunder scheduled regimes. Thirty samples were tested for freeze–thaw cycle tests. Table 1. Mix proportion, workability and strength of ASC(引用原文第二部分第二小点)（ppt第5页）The third subpoint is the methodsThe Freeze–thaw resistance was tested according to ASTM C666 and GB/T 50082-2009 “Standard for test methods of long-term performance and durability of ordinary concrete”. Six samples of each batch were tested, the average value of 6 samples was served as the finial freeze –thaw resistance. Mass and dynamic elasticity modulus were tested once after an interval of 25 times cycles, maximal cycle times (when relative dynamic elasticity modulus was 60% and percentage of mass loss was 5% at lowest) can denote freeze–thaw resistance of ASC. TDR-16V computer controlled concrete fast freeze–thaw cycle testing machine and DT-10W dynamic elasticity modulus testing machine were used to conduct the tests.(原文2.3 /ppt第6页)The third part is the resort , It has two subpoints 1.Microstructure and freeze–thaw resistance mechanism of ASC 2.Freeze–thaw resistance durability of ASC(ppt 第7页)Results of fast freeze–thaw cycle tests of ASC are listed in Table 3. As can be seen: (1) With the increase of freeze–thaw cycle times, relative dynamic elasticity modulus of ASC are descending slowly, this shows excellent ductility, relative dynamic elasticity modulus of A1–A5 are all about 90% at 300 times cycle（ppt第8页）(2) It is improper to set mass loss of ASC as the evaluation index of freeze–thaw destroy, because mass loss of A1–A5 vary indistinctively in the progress of freeze–thaw, it cannot reflect the destroy degree of concrete exactly, thus it is improper to use it to test and evaluate the freeze–thaw damage of ASC (which is shown in Fig. 1).（ppt第9页）The fourth part is the conclusion ,we can get two conclusions .The first is ASC used industrial waste –slag as raw materials, and it had excellent freeze–thaw resistance with frost-resisting grade of F300 at lowest, relative dynamic elasticity modulus were about 90% after 300 times freeze–thaw cycles, it also had little mass loss, surface freeze–thaw damage layers were very thin, which can effectively restrain freeze–thaw damage of concrete from worsening.(ppt第10页) The second is Different from freeze–thaw cycle damage models of PC, dynamic elasticity modulus attenuation models were superior to accumulative freeze–thaw damage models, and power function models were superior to exponential function models with better precision and relativity. （ppt第10页）Thank you very much for the privilege of presenting this paper。