Research On Preparation And Performance Of Self-compacting Concrete

Because of the character of good cohesion, stability, Uniform nature,and excellent Self-compacting performance,Self-compacting concrete(SCC) can greatly simplify the construction techniques of the concrete structure, enhance the construction efficiency and quality, shorten the construction period, and reduce the noise pollution. Although SCC is being used comprehensive in many domestic and foreign cities, there are hardly any engineering project cases of using SCC in Chongqing.Combing the characteristics of raw materials and the environment of Chongqing area, the thesis here has been made up SCC with good performance .And then analyzed the impact of raw material and preparation parameters on the rheological properties, the workability, and the mechanical properties through testing, as well as processing an test analysis of microstructure for the SCC with excellent comprehensive performance. Basing on this study, the thesis here also validated the actual quality of SCC in practical project by simulate pouring test in Actual project.The testing result indicated the following conclusions:①In this experimental condition, SCC can be obtained better performance by using water to binder ratio and binding material total are 0.30 and 580 kg/m3. When water to binder ratio and binding material total are 0.30 and 580 Kg/m3, the fixed fire ash and slag total replacements of cement are 30%, The weight ratio of fire ash and slag are 15%:15% and 10%:20%,SCC can be obtained better rheological performance ,workability,and the mechanical properties.when fixed fire ash and slag replacements of cement are 5% and 15%,after replaced silica fume, rheological performance and workability of SCC can be improved first, then be worse after. when silica fume replacements are 5%~7.5%,the rheological performance, workiability and the mechanical properties of SCC are also better.②In different sand modulus of fineness,both of the rheological performance and workability will be firstly improved but deteriorate then, and the best sand-aggregate ratio will decrease with the increase of the sand modulus of fineness. In this experimental condition,while adopting sands which sand modulus of fineness is 2.4, the compressive strength are larger.when sand modulus of fineness is 2.7 and sand-aggregate ratio is 48%, the combination performance of SCC are better. The workability and mechanical properties of SCC can be achieved the requirement of "self-compacting"while confected by hybrid sands. when the sand-aggregate ratio of mixed sands is 48% and the rate of machine-made sinds to extra fine sands is 1:1, all of the rheological performance, workability, and mechanical properties of SCC are well.③When coarse aggregate grain shape index I be bigger, the gradation to be better, the concretes mix viscosity can be smaller, all of the rheological performance, workability, and mechanical properties of SCC are better. In this experimental condition, SCC can be obtained better performance by selecting the weight ratio of two grain size of aggregates (10～20mm and 5～10mm) is 5:5.④The relations of mechanical properties of SCC and its confectioning methods is close. When the samples of SCC are formation, it will be advantageous for SCC with internal uniformity and stability mechanical properties by control the height of enter the mold in 50cm.the are also most superior When construction quality of project are checked and accepted, it should first used the statistical method to evaluate the mechanical properties of SCC.⑤The results of microhardness test,ZEISS metallography microscope and the SEM scanning electron microscope discovered that SCC can be obtained good contact surface transition region by"self-compacting". And that provided macroscopic mechanical properties and the lasting quality for the concretes.⑥The simulation pouring test results indicated that, After the surface observation, drill core law test method and so on examination intensity as well as ultrasonic wave examinations, we found that, even under the hot summer days megathermal climate, SCC have been obtained internal uniformity construction by pump over construction and hoisting transportation in the mold, and the mechanical properties of SCC were satisfied the design requirements, The simulation pouring test have been successfully. The SCC can be used in the actual project construction.