1.
The concrete mix proportion should be determined based on the design reference period and environmental conditions of the structure, according to the requirements of raw material quality, design strength grade, durability, construction technology, etc.
, referring to the “Code for Design of Ordinary Concrete Mix Proportion” (JGJ 55-2011) and the “Technical Specification for Construction of Highway Bridges and Culverts” (JTG/T 3650-2020), through calculation, trial mixing, adjustment and other steps.
The crack resistance performance of key component concrete mix proportions should be optimized and verified by trial pouring.
When the design has higher requirements for the durability index of concrete, its mix proportion should be determined separately through research.
When using statistical data of the same type of concrete to calculate and determine the standard deviation of concrete, for concrete of C30 and below, if the calculated strength standard deviation is less than 3.
0 MPa, the standard deviation used for calculating the formulated strength should be taken as 3.
0 MPa.
When there is no statistical data to calculate the standard deviation of concrete strength, the following table can be used for selection.
.