Influence of Aggregate Properties on Portland Cement Concrete Paving Mixtures Made with Lightweight Aggregates

摘要

Production of quality portland cement concrete (PCC) mixtures requires extensive knowledge ofthe component materials used to ensure the mixture design is correctly batched and theproduction process is controlled over the course of a project. This is especially true withaggregates, since they comprise approximately 70 percent of the mixture volume. This paperdocuments the use of coarse and fine lightweight expanded slate aggregates in a PCC mixturedeveloped for constructing high-temperature concrete (HTC) vertical landing (VL) pavementfeatures that will be exposed to extremely high temperatures. Various constructiondemonstrations were conducted to ensure that the laboratory-developed mixture proportion using100 percent lightweight aggregate was viable for the construction of two full-scale VL pads. Thephysical properties of the aggregates received for the project varied, requiring the field engineersto continuously modify the proposed mixture design on site. In addition to the variance inphysical properties between batches, the use of the lightweight fine aggregate in the constructiondemonstrations and the full-scale VL pads resulted in poor surface finishes on the placedconcrete. This paper provides a discussion of the effects of the changes in aggregate propertiesand their relationship to the production quality. Findings from this study reinforce the need forstringent quality control measures and material selection to create quality, economical VLairfield pavement features.