Research On The Performance Of Machine-Made Sand Concrete In Parts Of Yunnan Province

Mountain sand is deficient in resources in Yunnan Province, and the exploitation of river sand is also very difficult, so machine-made sand is to mostly used in many engineering practice by rock blasting and breaking then re-grading. However, the content of most machine-made sand in Yunnan Province with size less than 0.075mm is beyond limit required by natinal codes. It is often deemed as substandard material. Tests were carried out on machine-made sand particles with size less than 0.075mm. Tests on concrete made by machine-made sand were also performed in order to verify the influence of sand content on concrete properties, and to see if they would comply with the requirements of concrete pavement performance. A rational scientific basis is established for the application of machine-made sand on highway concrete pavement. The main work and conclusions are as follows:(1)Machine-made sand was to mostly used in many engineering practice by rock blasting and breaking then re-grading. However, part of less than 0.075mm in most of machine-made sand in Yunnan Province was beyond limit required by natinal specification. It is often deemed as substandard material.(2)First part of less than 0.075mm in machine-made sand was tested. The experimental results showed that they were not lay but stone powder. At the same time,it was unreasonable to assess the cleanliness of machine-made sand only with the method of sieving and washing. The standard test for sand equivalent value and methylene blue (MB) adsorption value test should be all taken into consideration.(3)The cement mortar and cement concrete added by the different content of the machine-made sand were tested. The results found that stone powder did not their strength when its content was below 30%.(4)Concrete were made under the premise that the rock powder content in the machine-made sand meets the certain requirements. The properties of concrete such as strength, shrinkage, creep, durability, frost resistance and etc. were studies by tests indoor. Results showed that as long as the rock powder content in machine-made sand meet the technical requirements in mix proportion design and that strength, durability, wearing quality resistance and other indexes will meet the application requirements of concrete road.(5)Because the properties of the machine-sand was special, the mix proportion design of the machine-sand concrete needed some specific technical requirements on raw materials, such as cement, coarse aggregate, fine aggregate, water and additives.Resources of limestone is so rich in Yunnan Province. So this experimental research on the one hand provides a technical support for"achieving the idea of"local conditions, local materials" and reducing costs in concrete pavement construction, on the other hand it provides an economical and feasible way for the promoting the use of machine-made sand in low-grade road at the counties.