The computer aided research of redispersable polymer powder on rapid repair mortar

The computer aided research of redispersable polymer powderon rapid repair mortarJiangwei Ji1，3，Zhang Ge1，3，Xuxun2，3（1. Shantou SEZ Longhu SCI.& pany limited, Shangtou city, Guangtong Province 515041; 2. School of material design and technology of Southwest Science and Technology University, Mianyan city, Sichuan Province,621010; 3. United laboratory of Southwest Science and Technology University- Longhu SCI.& pany limited, Mianyang city, Sichuan Province621010）Abstract：The uniform design method was applied in the paper, so the experiment scheme which conformed to the restrained condition within a large range could be designed, the experiment times could be reduced, and the scientific and representative of the compound system could be ensured. According to the conventional physical mechanical test of samples with different ratio in the designed experiment scheme, the relationship of the material composition and the property in the ternary compound system which composed of Portland cement–sulpho-aluminous cement–anhydrate was comprehensively studied, and the best ratio of the inorganic adhesive material was finally determined. The influence of the ratio of the main adhesive material of the repairing mortar on the strength and shrinkage property was studied on nonlinear regression analysis by SPSS (Statistical Package for the Social Science), the regression equation of the strength and shrinkage of the Portland cement, Sulpho-aluminous cement and anhydrate was built, and the quantitative study of the influence factor was realized. In the end, the proportion and the experiment was studied on the property of the polymer modified repairing mortar. The result of the uniform design satisfied the practical application according to the test, and the utilization was widespread.Key Words: ternary compound system, redispersable polymer powder, the uniform design, SPSS soft ware, nonlinear regression analysis1、prefaceAs the rapid development of construction in China, the traffic of the road was getting more and more busy, so did the airport runway. Although the repairing of the road and runway started, the traffic cannot be terminated. Because of the restriction, the repairing of the concrete road seems to be hard. So the rapid repairing method was applied to avoid the contradiction of the traffic.The earliest method to repair the cement concrete road was to removethe damaged concrete, and cover the road with the same or higher grade cement as the original design. The biggest disadvantage was that the strength development is slow, and the maintenance period and the termination of the traffic is long.In spite of that, the application of the ordinary cement concrete in thin-layer repair may not be compatible. The main problems are as follow: ①the shrinkage of the new pouring concrete was obviously heavier than the old one, so it is easy to get shrinkage-cracking; ②the viscosity of the cement concrete is low itself, so the bond strength with the old concrete is poor;③the disadvantage of the interface between the new and old concrete make the concrete easy to have fatigue cracks.For a long time, highway department apply asphalt concrete to repair the damaged cement concrete road, although the method is easy, and the termination is less time consuming, it still have a lot of shortcomings. ①the stiffness is quite different, causing different load transfer; ②if the adhesion between the base and the surface is not appropriate, and the reflection crack does not deal properly, the service life will be very short; ③the evenness and using function of the road is poor, and the color of it is not uniform. ④but we still use asphalt concrete to repair or recapping the concrete road at present if the damaged road surface is large.2 the main theory of the rapid repairing mortarIn this paper, we make the mixture which is composed of sulpho-aluminous cement, Portland cement and anhydrite in a proper proportion to hydrate. After the hydration, the ettringite that has the expansive characteristic will be formed[1]. At the same time, the repair mortar with rapid set, rapid hardening and low shrinkage performance can be produced in order to shorten the construction time, so the road can be put into service quickly. With the quality of rapid solidification, super early strength and good performance, the rapid repairing material get over the slow solidification and long curing time after the repair of the conventional repairing mortar. It has a wide utilization in repairing the damaged road surface by grouting, maintaining the airport runway, emergency repair for mine tunnel etc. The economic efficiency and the social efficiency are very good.3 the experiment scheme and result of the basic composition of the ternary compound systemScientific experiment that can help us recognize and understand the natureis a main method for scientific research. As an important branch ofmathematical statistics, the appliance of scientific experiment is gettingmore and more wide. According to the experiment design, we can arrangethe experiment times properly. We can get more useful information byapplying effective material conditions as much as possible with lessexperiment data available to ensure the representative and scientificity of thedata. Designed by Wang Yuan and Fang Kaitai in 1978, the uniform designis a method which only takes the dots scattered symmetrically within theexperiment range into consideration. The method makes sure how the dotsscatter in the experiment range evenly, so we can get the most informationthrough less experiment dots.We had to consider the restraint of which the total percentage of the rawmaterial was 100%. The orthogonal test can get the best ratio ortechnological parameter of the raw material, but the best composition is onlya combination of certain level of different factors, the exact best dot may beout of those dots. Comparatively, the uniform design is more applicable inthe condition of which the restraints can be ensured to maintain the dotswithin the range[2]. The experiment of our subject is the restraint formulaexperiment. There are three kinds of raw materials in the compound system,that is Portland cement, sulfo-aluminous and anhydrite. In our subject, wewant to find out the performance of the ternary compound system to obtainthe best proportion with which the best performance of early strength, highstrength, rapid hardening and smallest shrinkage can be realized. Havingbeen considered the sulpho-aluminous as the base material, the 1 daystrength and the resistance to the corrosion will be enhanced after theincorporation of the Portland cement, and ettringite will be more stable.Suppose that the ratio of sulpho-aluminous is bigger than 40%, anhydrite0-30% and Portland cement 0-30%. Referred to the uniform design methodand thought, and combined the experiment propose and comparison standardwith the project ,we have designed the experiment scheme by uniformdesign soft ware as Figure3-1 and Figure3-2 showed.table3-1 design of raw material ratio and result of performance testNumber EX1 EX2 EX3 EX4 EX5 EX6 EX7 EX8 SAC 93 87.9 84.4 81.5 79.1 76.9 74.9 73 OPC 3.86 1.18 9.89 3.28 15 5.98 20 9.16 Anhydrite 3.11 10.9 5.7 15.2 5.97 17.2 5.15 17.9 Total 99.97 99.98 99.99 99.98 100.07 100.08 100.05 100.06 Water requirement30.71% 30.14% 32.14% 28.57% 31.00% 30.00% 30.57% 30.71%of normalconsistencyInitial setting/min 8 7 9 12 4 7 4 6 Finalsetting/min16 15 18 19 9 13 6 18Compressive strength/Mpa 1d 52.20 53.10 53.80 52.45 54.65 51.85 52.05 52.45 3d 61.75 64.30 62.65 60.90 63.50 60.50 61.15 62.35 7d 71.00 69.40 67.95 69.40 70.75 66.85 70.75 66.35 28d 73.38 74.35 76.58 72.53 77.93 74.93 78.58 76.73Flexural strength /Mpa 1d 3.73 2.60 2.37 3.61 2.20 3.82 4.72 5.04 3d 2.41 2.32 1.45 2.88 1.90 2.09 2.86 3.49 7d 2.58 2.25 2.70 3.07 2.39 3.21 1.78 3.56 28d 1.98 2.51 2.07 5.52 2.29 2.97 2.99 5.75Shrinkage rate/% 1d 0.113% 0.125% 0.103% 0.140% 0.060% 0.118% 0.101% 0.111% 3d 0.156% 0.152% 0.154% 0.181% 0.101% 0.155% 0.130% 0.139% 7d 0.269% 0.189% 0.189% 0.210% 0.128% 0.183% 0.164% 0.175% 28d 0.238%0.238%0.237% 0.265% 0.167%0.236% 0.210% 0.232%table3-2 design of raw material ratio and result of performance test Number EX9 EX10 EX11 EX12 EX13 EX14 EX15 EX16 SAC 71.2 69.6 66.5 63.8 61.2 55.3 53.2 51.2 OPC 25.2 12.8 16.7 21 25.7 16.3 20.9 25.7 Anhydrite 3.57 17.7 16.7 15.2 13.2 28.3 25.9 23.1 Total 99.97 100.1 99.9 100 100.1 99.9 100 100 Water requirementof normalconsistancy31.00% 31.00% 30.29% 30.29% 31.00% 29.29% 29.43% 29.43% Initial setting/min 8 5 4 7 9 6 9 11 Final setting/min 9 14 6 8 10 9 12 14Compressive strength/Mpa 1d 47.65 53.45 53.10 46.75 45.50 45.15 41.80 43.60 3d 62.05 68.20 64.00 64.20 59.50 60.10 56.80 57.40 7d 70.15 70.70 69.50 67.60 72.95 64.65 68.50 67.80 28d 73.38 75.45 80.85 80.30 85.60 75.13 79.28 82.30Flexural strength/Mpa 1d 3.73 4.92 3.63 3.30 4.22 4.88 3.63 3.75 3d 2.51 4.20 4.78 3.47 2.79 3.52 2.81 3.19 7d 1.99 2.74 3.05 1.99 1.64 2.88 1.83 1.99 28d 1.98 6.33 5.00 5.76 4.23 6.21 4.89 4.35Shrinkage rate/% 1d 0.081% 0.036% 0.083% 0.044% 0.028% 0.008% 0.045% 0.026% 3d 0.108% 0.049% 0.104% 0.061% 0.044% 0.031% 0.064% 0.046% 7d 0.136% 0.075% 0.119% 0.116% 0.071% 0.080% 0.108% 0.112% 28d 0.148% 0.131% 0.184% 0.153% 0.112% 0.124% 0.164% 0.176%4 treatment and analysis of experiment dataIt is complicate to deal with the data from uniform design. So we usually apply multi-regression method to deal with the data, and use software to aidit. In our experiment, we use SPSS statistical analysis software to finish regression analysis. Because there is interaction between the three materials, we introduce non-linear regression analysis method to fit.The springboard of uniform design is to build the multivariate optimizing model. The data of the experiment can be dealt with by screening variable, such as stepwise regression. Normally, the quadratic polynomial can be founded by the result of uniform design. If there are m factors X1，X2，……X m , and the observation index is Y, the quadratic index is :Y=B0+ΣB i X i+ΣB ii X i+ΣB ij X i X j+εIn the equation: B0、{Bi}、{Bii}、{Bij}—regression parameter,(i<j)ε— random errorThe quadratic polynomial was built up by the appliance of SPSS software. In the non-linear regression analysis, the parameter and the model fraction had been set. The output of the linear regression data was showed as table 4-1 to table 4-4[4].Table 4-1 Regression equation of compressive strength ParameterEstimatesParameter Estimate Std. Error95% Confidence IntervalLower Bound Upper BoundB0 -0.199 1,176.154 -2,878.144 2,877.746 B1 0.717 11.752 -28.039 29.472B2 -0.025 11.510 -28.188 28.139B3 -2.179 12.193 -32.014 27.657 b11 0.010 0.000 0.010 0.010b22 0.480 5.722 -13.522 14.482 b33 0.000 0.000 0.000 0.000b12 0.010 0.020 -0.040 0.059b13 0.034 0.012 0.005 0.063b23 0.076 0.029 0.005 0.147 Table4-2 Regression equation of compressive strengthANOVA(a)Source Sum of Squares df Mean SquaresRegression 95,849.642 10 9,584.964 Residual 30.526 6 5.088 UncorrectedTotal95,880.168 16CorrectedTotal198.212 15Table4-3 Regression equation of shrinkage rateParameter EstimatesParameter Estimate Std. Error95% Confidence IntervalLower Bound Upper Boundb0 1.129 23.650 -56.742 58.999b1 -0.029 0.237 -0.609 0.552b2 -0.023 0.247 -0.626 0.581b3 -0.072 0.935 -2.361 2.216b11 0.926 0.679 -0.735 2.587b22 0.982 0.334 0.165 1.799b33 1.018 0.238 0.435 1.600b12 0.000 0.004 -0.010 0.011b13 0.000 0.006 -0.015 0.015b23 0.000 0.005 -0.013 0.014Table4-4 Regression equation of shrinkage rateANOVA(a)Source Sum of Squares df Mean SquaresRegression 0.591 10 0.059Residual 0.012 6 0.002 UncorrectedTotal0.603 16Corrected Total 0.035 15The analysis table and formula of the variance of compressive strength and shrinkage rate: Decision coefficient=1-residual square sum /correction sum of square sum , we can get two model decision coefficients which are 0.854 and 0.834. With the SPSS software, the compression equation and shrinkage rate equation are:Y1=-0.199+0.717X1-0.025X2-2.179X3+0.01X12+0.48X22+0.01X1X2+0.0 34X1X3+0.076X2X3Y2=1.129-0.029X1-0.023X2-0.072X3+0.926X12 +0.982X22+1.018X32Linear RegressionPredicted Valuescom pre ss ion st ren gthc om R -SFigue1 the standard regression predictive dots of the sample of 28 dayscompression strengthFrom the figure1, there was the linearship between the standard predictive value and the actual value, and the slope is 1. The dots fluctuated from the line, but not vialently. We concluded that the fit between the model equation and objective function was very well. At the same time, the regressionmodel expressed the influence of the objective variant on the factors well.5 Experiment of rapid repair mortarThere are three kinds of cementicious materials in rapid repair mortar with best ratio. Considering the fluidity and strength of the system, the total percentage of the cementicious material was 45%. We applied the best water PCE reducer to better workability and condense the system, so the early strength and high strength could be gained. Besides, the appliance of VINNAPAS 5011 redispersable polymer powder could enhance the cohesive strength between the repair mortar and the interface, and the cohesive to the old concrete would be last long. The basic ratio is as follow: cementicious material 45%, sand 53%, early strength agent0.2%, water reducer 0.15%, retarder 0.05%, enhancer 2%. The result showed as table4-1.accord with the application requirement.6 Conclusion（1）The rapid repair mortar with good property can be made by the appliance of ternary compound system composed of Portland cement, sulpho-aluminate and anhydrite, so the excellent social efficiency and the economy efficiency of the road ,such as rapid repair, durability, and rapid open to traffic, will be attained.（2）With the uniform design , the best model can be found quickly, so the experiment times can be reduced and the expenditure can be reduced. （3）With SPSS to fit the uniform experiment data, the regression equation which can fit well can be founded. The influence of model variant on factors will be more clear and quantitative, so it is a good guiding role for the study of real product.reference[1] Sheng Wei, Huang Wenxi, Min Panrong,《cement technology》，Wuhan TechnologyUniversity Publishing House 2000.8:318-320[2] Fang Kaitai, Ma Changxing, Design of Orthogonal test and Uniform Design[M].Beijing Science Publishing House.2001:144一152[3] Fu Xinghua, Hou Wenping. The Study on the Improvement of the Property of Sulpho-aluninate[J].Cement Technology2001.2：10-16[4] Zhang Wentong.SPSS11 The Statistical Analysis, Beijing Hope Electric PublishingHouse 2002.6：140-145。