Study On Influencing Factors And Preparation Technology Of Fair-faced Self-compacting Concrete

Fair-faced self-compacting concrete is a new type of green concrete.It not only has the characteristics of large fluidity and self filling of self-compacting concrete,but also has the characteristics of one-time molding of fair-faced concrete without any decoration.Therefore,fair-faced self-compacting concrete is favored by more and more project builders.In order to find out the influencing factors of the performance of fair-faced self-compacting concrete,this paper focuses on the preparation of fair-faced self-compacting concrete,and combines experimental research with theoretical analysis to study the working performance,mechanical properties,apparent properties and preparation technology of fair-faced self-compacting concrete.The results show that:(1)The influence law of basic factors on the performance of fair-faced self-compacting concrete is mainly as follows: the change of sand ratio and water binder ratio has a significant impact on the fluidity of concrete mixture,while the glue sand ratio has no significant impact on the fluidity of concrete mixture.When the sand ratio is 48%,the water binder ratio is 0.44 and the glue sand ratio is 0.58,the fluidity of concrete mixture is the best;The change of binder sand ratio has a significant impact on the 7d compressive strength of fair-faced self-compacting concrete,and the sand ratio and water binder ratio have no significant impact on the7 d compressive strength of fair-faced self-compacting concrete.Under the best test conditions,the best ratio of sand ratio is 50% and the best ratio of water binder ratio is0.36.(2)The influence of admixtures on the performance of fair-faced self-compacting concrete is mainly as follows: with the increase of fly ash content,the fluidity of concrete mixture first increases and then decreases,and the compressive strength of concrete at 7d and 28 d shows a trend from high to low.When the content of fly ash is 10%,the compressive strength and flexural strength of concrete are the largest;With the increase of silica fume content,the fluidity of concrete mixture shows a downward trend,and the compressive strength and flexural strength at 7d and28 d show an upward trend.When the silica fume content reaches 30%,the strength reaches the maximum;With the increase of slag powder content,the fluidity of concrete mixture shows an increasing trend,and the compressive strength and flexural strength at 7d and 28 d show a downward trend.When the slag powder content reaches 10%,its strength reaches the maximum.(3)The ternary combination of polycarboxylic acid water reducer,defoamer and air entraining agent can effectively improve the pore structure of concrete and make the bubble quality of concrete reach the best state,so as to improve the properties of concrete.Among them,when the content of defoamer is 0.50 ‰ and the content of air entraining agent is 0.16 ‰,the working performance of fair-faced self-compacting concrete is the best;When the content of air entraining agent is between 0.05% ～0.10% and the content of defoamer is between 0.50% ～ 0.70%,the concrete meets the design requirements of compressive strength and has little influence;When the content of defoamer is 0.50 ‰ and the content of air entraining agent is 0.10 ‰,the pore size distribution and size of concrete surface are the best.