Abstract
Cemented sand and gravel (CSG) material is a new type of dam material developed on the basis of roller compacted concrete, hardfill, and ultra-poor cementing materials. Its main feature is a wide range of sources of aggregate (aggregate is not screened but by simply removing the large particles it can be fully graded on the dam filling) and low amounts of cementitious materials per unit volume. This dam construction material is not only economical and practical, but also green and environmentally friendly. There are many factors affecting the mechanical properties of CSG materials, such as aggregate gradation, sand ratio, water content, water–binder ratio, fly ash content, admixture content, etc. Based on the existing research results of the team, this paper focuses on the influence of fly ash content on the compressive strength of CSG materials. Through a large number of laboratory measured data, we found: (1) The compressive strength law of materials at different ages; the compressive strength of CSG material at age 90 d is generally 10%~30% higher than that at 28 d, and it is proposed that 90 d or 180 d strength should be used as the design strength in the design of CSG material dam; (2) There is an optimal value of fly ash content in CSG materials: when the fly ash content is 50% of the total amount of cementitious materials (cement + fly ash), the fly ash content is defined as the optimal content, and the test data are verified by regression analysis. The discovery of an ‘optimal dosage’ of fly ash provides an important reference for the design and construction of CSG dams.
Highlights
Cemented sand and gravel (CSG) is a new material for dam construction works, produced by adding cementitious materials and water to accessible rock based material, including sand and gravel at the river bed or excavation muck near the dam site, and mixing them with simple equipment and process
This paper mainly focused on the influence of fly ash content on the strength of CSG material, so the proportion of other materials followed the reference of previous studies with the water–binder ratio at 1.0, sand ratio at 20%, coarse aggregate ranging from 20–40 mm, and 5–20 mm, mass ratio at 6:4, and cement content of 50 kg/m3 and 60 kg/m3
As a new type of eco-friendly material for dam construction, CSG is a low-cost material as it requires a lower amount of cement content and higher fly ash content than traditional ones
Summary
Cemented sand and gravel (CSG) is a new material for dam construction works, produced by adding cementitious materials and water to accessible rock based material, including sand and gravel at the river bed or excavation muck near the dam site, and mixing them with simple equipment and process. Compared with an RCC dam, it demands less cement, with simplified aggregate preparation and mixing facilities. Temperature control measures are not necessary in the construction. As a result, it can effectively speed up the construction and lower the project cost. A CSG dam requires a significantly lower amount of engineering works, but has batter capacity to withstand seepage deformation and scouring. CSGD is a new kind of constructed dam that is economic, safe, low carbon, and eco-friendly
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