Research On The Preparation Of High Performance Silicate Ceramsite And Its Application In Concrete

This subject conducts research on the resource utilization of coal cinder and uses it as the main raw material in the preparation of silicate ceramsite.By studying the influence of cinder powder fineness,mixing ratio and shell structure on the performance of silicate ceramsite,the purpose of preparing high-strength shell silicate ceramsite can be achieved.Taking the shell silicate ceramsite as the research object,a comprehensive study on its mechanical properties and durability;the shell silicate ceramsite high-strength concrete was prepared and the freeze-thaw resistance study of the concrete was carried out;Research on the application of shell-silicate-ceramsite in the field of prestressed high-strength concrete pipe piles was carried out.Study on preparation and performance of cinder silicate ceramsite.The cinder powder fineness,mixing ratio and shell structure were studied to realize the preparation of high-strength shell silicate ceramsite.The apparent density of this kind of shell silicate ceramsite is 1940.1kg/m³and the water absorption rate is 2.3%in 1 hour.The cylinder compressive strength reaches 24.3MPa,which has the characteristics of low water absorption and high cylinder pressure strength.Carrying out the soundness study on the shell silicate ceramsite,the quality loss is only 1.7%,which meets the national standard soundness index class I requirements.A rapid alkali-silicic acid reaction study was conducted on the shell silicate ceramsite,and its 14d expansion rate was 0.0341%,which was lower than the standard judgment value of 0.10%,it did not have the hazard of alkali aggregates;at the same time,when the presence of SO₃in the cinder was considered,during the experiment the combined effect of the alkali-silicic acid reaction expansion and the expansion of ettringite on the expansion performance of the sample shows that when the SO₃content reaches 3.5%,the expansion rate of the sample at 14d is 0.0561%,which is still less than 0.10%.In addition,the crushing index,softening coefficient and freeze-thaw quality loss of the shell silicate ceramsite were studied,and the results were 2.2%,0.96 and 1.28%respectively,all of which met the standard requirements.Research on preparation and anti-freeze-thaw of high-strength silicate ceramsite concrete.Under the condition of 400kg/m³cement and W/C=0.4,the compressive strength of ceramsite concrete standard curing 28d reached 63.4MPa,the flexural strength was 11.4MPa,and the dry apparent density was 2018.6kg/m³.Compared with ordinary concrete under the same conditions,the compressive strength and flexural strength were increased by 3.8%and 8.6%,respectively,and the dry apparent density was reduced by 16.2%.Put the ceramsite concrete in a frozen state,and the freeze-thaw solution is water,3%Na Cl,5%Na Cl,5%Na₂SO₄,10%Na₂SO₄solution,and perform 50 freeze-thaw cycles.After freezing and thawing,each group of ceramsite concrete exhibited good frost resistance performance,the relative dynamic elastic modulus was between 98.6～102.3%,the quality showed a slight increase,the increase range was 0.30～0.50%,the compressive strength loss rate Between-2.1～2.4%.The effects of different proportions of ceramsite on freeze-thaw performance of ceramsite concrete were studied.The results show that when the volume ratio of ceramsite is 40～50%,the increase of the proportion of ceramsite can improve the antifreeze performance of concrete.It shows that ceramsite as coarse aggregate can help improve the frost resistance of concrete.The application of shell silicate ceramsite in the field of prestressed high-strength concrete pipe piles.Under the condition of 480kg/m³cement and W/C=0.25,the steam curing strength of ceramsite concrete pipe pile is 91.1MPa and the autoclave curing strength is106.9MPa,which meets the standard requirements.Exploring the admixture effect of mineral admixtures,it was found that under the condition of a single admixture,the addition of fly ash,slag and quartz powder can improve the fluidity of concrete,and the improvement effect of fly ash is the most obvious.And the addition of fly ash is beneficial to improve the steam curing strength of the sample,and the addition of quartz powder has the most significant improvement in the sample’s autoclave curing strength;the study on the mixing of admixtures found that reasonable mix can play a complementary role in the advantages of admixtures,for example:the samples of fly ash and quartz powder mixed with high steam curing strength and autoclave curing strength,in addition,the ratio of splitting tensile strength to compressive strength of the mixed sample is higher than that of the single mixed,indicating that the mineral admixture can be mixed to improve the problem of high brittleness of concrete when mixed alone.The effects of three ceramsite curing processes of natural curing,steam curing and autoclaved curing on the performance of ceramsite concrete pipe piles were studied.The steam curing strength and autoclaved strength of the three types of ceramsite concrete are between 71.8～78.6MPa and 125.9～134.1MPa respectively,and the fluctuation range is small,indicating that the curing condition of ceramsite has little effect on the strength of concrete pipe piles.The effect of C/S of cementitious materials on the performance of concrete under the condition of large volume of fly ash is studied.The results show that when C/S=1.0,the hydration phase type and hydrate content in concrete work best together,steaming The maximum compressive strength is 124.5MPa.And the anti-freezing experiment was carried out on the ceramsite concrete with different C/S.The results showed that the increase in C/S reduced the anti-freezing performance of the concrete.The sample with the C/S of 0.6 had the best anti-freezing performance and the frost resistance level is D168.The sample with C/S of1.2 is the worst in frost resistance,and the frost resistance level is D107.According to the analysis of the failure mode of the sample,the main reason for the freeze-thaw failure is the micro-crack failure in the concrete matrix.