Because lightweight aggregates have a lower specific gravity, they tend to float to the surface if over-vibrated. ACI 213R-14 offers field best practices for:
, serves as the primary technical standard for designing, proportioning, and applying structural lightweight concrete (SLC) to reduce dead loads while maintaining structural integrity. The guide outlines essential practices for managing aggregate absorption, implementing internal curing, and adjusting design calculations for reduced modulus of elasticity and shear capacity. For further details, see the ACI 213R-14 presentation on SlideShare 213r 14-guide-for-structural-lightweight-aggregate-concrete
The ACI 213R-14 is more than just a technical manual; it is the bridge that allows normal-weight concrete codes to be applied to lightweight materials. Without this guide, engineers would lack the specific modification factors required to calculate shear resistance, development length, or deflection for lightweight concrete. The document's reaffirmation in 2023 indicates that the industry continues to rely heavily on its guidance for modern construction challenges, including seismic retrofitting and the construction of floating structures. aci 213r-14 pdf
Reduced seismic inertial forces (lower building mass yields lower earthquake loads). Fewer prestressing strands in post-tensioned slabs. 2. Deflection Control
Proportioning lightweight concrete requires a different approach than normalweight concrete due to aggregate absorption rates. ACI 213R-14 outlines: For further details, see the ACI 213R-14 presentation
The most direct and reliable source is the at www.concrete.org . Searching for "ACI 213R-14" will lead to the official listing. Key details include:
Pumping lightweight concrete introduces unique challenges. The pressure from the concrete pump can force water out of the paste and deep into the pores of the lightweight aggregate. This causes the mix to dry out, stiffen, and potentially plug the line. Reduced seismic inertial forces (lower building mass yields
Aggregates must be continuously pre-wetted in the stockpile via sprinkler systems prior to batching. If dry aggregates are introduced directly into the concrete mixer, they will rapidly absorb batch water, causing a sudden loss of slump and workability during transit. Placement and Pumping
) used in building codes (like ACI 318) to reduce the calculated shear and development length capacities for lightweight concrete.