Study Of Main Technical Requirements In High Quality Concrete Aggregate

As the natural high quality sand and pebble drying up and limiting mining,mechanism sand and gravel are becoming a main source.Modern concrete is given priority to with flow state,and concrete demand on the workability of is higher,so concrete demand on aggregate.However,quality of sand is poor,mainly reflecting in its bad gradation and grain shape,resulting in big cementitious materials consumption and water consumption.Because the quality of aggregate is variable used in the production,tube plugging,segregation and bleeding problems in the process of concrete construction are frequent.The quality of the aggregate has become the bottleneck of the development of modern concrete technology.Poor aggregate seriously restrict the development of engineering quality.Improving the quality of sand and gravel is the only way to improve the concrete industry and technology.The definition of high performance concrete require the use of high-quality raw materials.It is imperative to put forward and establish the technical system and the requirement of high quality aggregate.Based on the analysis of the problems existing in the current standard and regulation of aggregate,the aggregate grain shape,gradation,strength and surface texture are studied.It provides technical support and reference to standard of aggregate in high performance concrete for China aggregate association.For aggregate grain shape,due to the defined of coarse aggregate needle flake is broad in current standards,the actual aggregate grain shape is poor and irregular shape particles are so many;There is no the concept of particle shape and the request in mechanism sand production,causing the mechanism of sand particle shape is generally poor.This topic defines the irregular particles of coarse aggregate and elongated particles of the mechanism sand through test research,and invents the corresponding test methods.Based on the test data and analysis which influence of aggregate grain shape on mortar and concrete,put forward control values of high quality aggregate for the irregular particles of coarse aggregate and elongated particles of the mechanism sand.For aggregate gradation,analyze the national standards of fine aggregate,and study the effects of different gradations on the performance of mortar and concrete.It thinks that through the gradation zone of cumulative triage formed to control gradation of fine aggregate appear to breaking grading.Test confirmed that concrete performance is different using different fine aggregate belong to the second area.Recommend that use grader retained percentage as control indicators of building sand.Control target of grader retained percentage is putted out.By studying the influence of basalt and limestone gravel on different strength grade concrete,it is found that the main factors influencing the strength of concrete is aggregate surface texture for low strength grade concrete,rather than the aggregate strength and water absorption.For the high strength grade concrete,aggregate strength and surface texture both affect the strength of concrete.This topic researching in high quality aggregate grain shape,gradation,etc has made innovative achievements,and puts forward the new concepts,new ideas and method;Research and analysis the influence mechanism of the strength and surface texture of coarse aggregate on concrete strength.Lay the necessary foundation for the establishment of technology system and the standardization construction of the high quality aggregate.