CODE 350-20: Code Requirements for Environmental Engineering Concrete Structures (350-20) and Commentary (350R-20)


The “Code Requirements for Environmental Engineering Concrete Structures” (Code) portion of this document covers the structural design, materials selection, and construction of environmental engineering concrete structures. Such structures are used for conveying, storing, or treating water and wastewater, other liquids, and solid waste. The term “solid waste” as used in the Code encompasses the heterogeneous mass of disposed-of materials, as well as more homogeneous agricultural, industrial, and mineral wastes.

The Code also covers the evaluation of existing environmental engineering concrete structures.

Environmental engineering concrete structures are subject to uniquely different loadings and severe exposure conditions that require more restrictive serviceability requirements and may provide longer service lives than non-environmental structures.

Loadings include normal dead and live loads, earth pressure loads, hydrostatic and hydrodynamic loads, and vibrating equipment loads. Exposures include concentrated chemicals, alternate wetting and drying, high-velocity flowing liquids, and freezing and thawing of saturated concrete. Serviceability requirements include liquid-tightness, gas-tightness, and durability.

Proper design, materials, and construction of environmental engineering concrete structures are required to produce serviceable concrete that is dense, durable, nearly impermeable, and resistant to relevant chemicals, with limited deflections and cracking. This includes minimizing leakage and control over the infiltration of, or contamination to, the environment or groundwater.

The Code presents additional material as well as modified portions of the ACI 318-05, ACI 318-08, and ACI 318-11 building codes that are applicable to environmental engineering concrete structures.

The Commentary discusses some of the considerations of the committee in developing the ACI 350 Code, and its relationship with ACI 318. Emphasis is given to the explanation of provisions that may be unfamiliar to some users of the Code. References to much of the research data referred to in preparing the Code are given for those who wish to study certain requirements in greater detail.

The chapter and section numbering of the Code are followed throughout the Commentary.

Among the subjects covered are: drawings and specifications, inspections, materials, concrete quality, mixing and placing, forming, embedded pipes, joints, reinforcement details, analysis and design, strength and serviceability, flexural and axial loads, shear and torsion, development of reinforcement, slab systems, walls, footings, precast concrete, prestressed concrete, shell structures, folded plate members, provisions for seismic design, and an alternate design method in Appendix A.

The quality and testing of materials used in the construction are covered by reference to the appropriate standard specifications. Welding of reinforcement is covered by reference to the appropriate AWS standard. Criteria for liquid-tightness and gas-tightness testing may be found in ACI 350.1.

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