| FORWORDBricklaying is a primary structure form of our building construction. Clay brick is a general and traditionary bearing wall material in the industry and civil build. Because the clay brick destroy the infield, consuming power high and benefit low, it hasn't fitted need of our building development.Our electric power is mostly make up of coal and account for 80% or so. With the rapid development of electric power, Pulverized fuel ash (simple as PFA) sharply increase. But because PFA it too bad, which make it's use difficult and the ratio of the average use is less than 40%. Two-exempt PFA brick is the new type of brick, which needn't sinter and curing in the normal temperate and pressure. With the development of architecture industry technique and new materials, this new sort of PFA brick is the ideal instead product of clay brick.The two-exempt PFA brick is made of cement, PFA, fine aggregation and variance of admixture arousing the activity of PFA, and it formed by mold pressing and natural curing addition. In this experiment, the physics and chemical performance, compressive strength and freezing-thawing performance, and etc on, of the 22 set of the two- exempt PFA brick of the are tested. Using the method of orthogonal design, some best mixture ratio of all can be obtained by adjusting all kinds of the material mixture ratio, which meet or exceed the target of the fly ash brick at the present. In the meanwhile, the correlation between the compressive strength, the freezing and thawing performance and the materials are presented. Though the theory analysis and calculation, the proposal mixture ratio of the MU10 and MU15 of the two- exempt is given. On the base of this, the industry produce of PFA brick is studied, emplodered and spread, which piles data for the primary compiling of the code for construction. The active stimulation, the response mechanism, the calculation formula of the compressive strength and shear strength of the PFA brick are given out.RESEARCH OF THE EXPERIMENTOrthogonal design is the method to deal with the experiment of several factors. The factors of the orthogonal design are the effective ingredient of the index. The levels of the orthogonal design are the frondose condition to compare in the experiment. Because the compressivestrength and freezing and thawing are discussed in the paper, the primary factors ------PFA,cement, water, fine aggregation and variance of admixture ------of the lots of materials areselected. Three levels are chosen for each factor.The nine set of is designed in the experiment for each orthogonal design. The compressive strength is six and freezing and thawing is three to four for "A" set. The compressive strength is three and freezing and thawing is six for "B" set. The compressive strength for twenty days is six and the compressive strength for thirty days is six for "C" set. The total number of each set is nine to ten.THE ANALYSIS OF THE EXPERIMENT RESULTSThrough the analysis of the orthogonal design of the "A" and "B" set. Each material effect on the compressive strength and freezing and thawing of the PFA brick, and etc on. The most effect on the compressive strength is the cement. The effect on the compressive strength after the freezing and thawing basically is the same as before the freezing and thawing. The best proposal mixture ratio of the two-exempt PFA brick is discovered. Fig 1 and Fig 2 are the correlation between the compressive strength and freezing and thawing performance of the each material and each level.Fig.l The correlation between the compressive strength and each levelFig. 1 The correlation between specific absorption and each levelThrough the compressive strength, cement is the most factor of all the material effect on the PFA brick. The more the amount of the cement is, the higher of the compressive strength of the brick and they are change in linear. The other material effect on brick is less than cement and the dispersity is more than cement. The more amount of the PFA is, th... |
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