模拟国际会议演讲稿

1. IntroductionThank you very much. Mr. Jiao, for your kind introduction. Ladies and gentlemen, Good afternoon! My name is Lijia, came from Harbin Engineering University. I am honored to have been invited to speak at this conference. Before I start my speech, let me ask a question. Do you know what can affect the properties of foam concrete? Do you think how to reinforced the properties of foam concrete？Most of the investigations on foam concrete in the past have been conned（被限于） to neat cement paste, cement paste with partial replacement with admixtures and to cementsand mixes. Today, my topic is about Inuence of ller type on the properties of foam concrete. I want to share our interesting research result on reinforced concrete frame with you. The content of this presentation is divided into 4 parts: In section 1, I will introduce what is the foam concrete. In section 2, I will talk about Parameters investigated and mix compositions. In section 3, I will give Eect of watersolids ratio on design density. And finally, I will make a conclusion.2. BodySection 1: the foam concreteNow, I will introduce the foam concrete. Pre-formed(成型的) foam concrete is manufactured（加工）by adding foam, prepared by aerating（充气）a foaming agent solution, to cement paste or cement mortar（灰浆）. The composition（合成物）, physical properties（性能）and uses of foam concrete were discussed in detail（详细的）by Valore, Short and Kinniburgh, Rudnai and Taylor. Although several investigations have been conducted on the properties of foam concrete, most of them deal with cementsand mixes, neat cement paste with or without partial replacement（局部替换）using admixtures（掺合料）. Few studies report on the inuence of ller type on the properties of foam concrete. By using y ash（粉煤灰）as ller (ne aggregate细骨料) instead of sand, the high volume（体积）utilization（利用）of y ash becomes possible可能, thus providing a means of eco-nomic（经济）and safe disposal（处理）of this waste product. Comparison（比较）of strength of air-cured foam concrete made with cement-sand and cementy ash for masonry（砌体结构）by Durack and Weiqing show that for products of comparable density（比较密度）, mixes with y ash as ne aggregate in place of sand gave relatively higher strength.Section 2: Parameters(参数)investigated and mix compositions（组成成分）So much for the foam concrete, now I will move on to Parameters(参数)investigated and mix compositions. As the experimental programme(实验程序)was aimed at studying the eect of the llers on the properties like density（密度）, ow behaviour（流动特性）, water absorption（吸水率）and strength of foam concrete, the following mixes were investigated by keeping the basic llercement ratio constant（恒定不变）at 1:1 by weight. The foam required for three densities（密度）of foam concrete viz. 1000, 1250, 1500 kg/m3 were arrived at as per ASTMC 796-97. In the cementsandy ash mixes 50% of the sand is replaced with y ash and in the cementy ash mixes all the sand is replaced with y ash.Section 3: Eect of watersolids ratio（水砂比率）on design densityThat bring me to Eect of watersolids ratio（水砂比率）on design density. I think this part is the most important in my presentation, I will explain in detail. As the foam is added to the wet foam concrete mix, the consistency（稠度） of the wet mix is very important to get the design density. Fig. 2(a) and (b) show the variation of density ratio（密度变化率）(measured fresh density divided（分离）by design density) with watersolids ratio for mixes with dierent ller type for each of the design densities, viz., 1000 and 1500 kg/m3, respectively（分别地）. It is observed that at lower watersolids ratios, i.e., at lower consistency, the density ratio is higher than unity（个体）. The mix is too sti（严格地）to mix properly thus causing the bubbles（气泡）to break during mixing resulting in increased density. At higher watersolids ratios there is also an increase in density ratio as higher water contents make the slurry（泥浆）too thin to hold the bubbles resulting in segregation（分离）of the foam from the mix along with segregation of the mix itself thus causing an increase in measured density. Therefore, as shown in Fig. 2(a) and (b), a density ratio of unity or nearly unity is achieved only at a particular consistency. This consistency requirement for the mix before adding foam to it can be expressed in terms of watersolids ratio. It is also observed that the watersolids ratio required to obtain a density ratio value of one, depends on the ller type.Section 4: ConclusionThe conclusions drawn from this study and summarized below are applicable（合适的）to the characteristics of the materials（材料特性）used and the range of parameters（参数范围）investigated: (i) the consistency of pre-formed foam concrete mixtures (dened as the watersolids ratio for achieving the target（目标）density) mainly depends on the ller type, i.e., relatively higher for mixes with y ash as ller compared to mixes with sand; (ii) the ow behaviour mainly depends on the foam volume and as the foam volume increases the ow decreases. For a given density, foam concrete with y ash as ller showed relatively（相当的） higher ow values; (iii) for a given density, an increase in y ash content of the mix results in increased strength. In comparison（比较）to cementsand mixes, cementy ash mixes showed relatively higher water absorption（吸收）.Thats all. Thank you! Are there any questions?The picture on this slide is So much for ., now I will move on to.This slide shows the calculation resultAs we know, the target user usually has taken a list of courses rather than a course, so we need to extent our probability calculation formulars. For example, suppose T=a,b, PrxT the probability x occurs without either an a or b preceding it; PrxT the probability x occurs without either an a or b following it. This probability can be