Optimisation of mix proportions for the cemented sand and gravel in cold region

Abstract

Cemented sand and gravel (CSG) is recognised as having poor quality due to its high porosity. An experimental study was carried out on the mix proportion design of CSG, taking into account the strength and frost resistance requirements of CSG dams in frozen areas. The main factors affecting the compressive strength and frost resistance of CSG were determined by orthogonal experiments. The influencing factors are water/binder ratio, fly ash, cement consumption, admixture and sand ratio, every factor sets up two cases, and the orthogonal table L8 (24) is adopted. There is a positive correlation between compressive strength and frost resistance, as the test results show. An optimal function about compressive strength and frost resistance to improve the quality of CSG in cold region was proposed, in which, weight was determined by OWA operator and entropy weight method to eliminate the influence of extreme values in the subjective evaluation. With the application of the function, significant factors influencing the desired performance of CSG are sand ratio, cement consumption, water/binder ratio and content of fly ash, while the optimum mix proportion is water/ binder ratio of 1.0, ratio of sand of 0.2, while 60 kg/m3 and 40 kg/m3 for the contents of fly ash and cement. The results can provide a theoretical basis for application and design of CSG dam in cold region.