Accession Number : AD0732224

Title :   Aggregate Investigations, Milford Dam, Kansas; Examination of Cores from Concrete Structures.

Descriptive Note : Technical rept.

Corporate Author : ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MISS

Report Date : JUN 1963

Pagination or Media Count : 85

Abstract : Eleven concrete cores from structures in Kansas and Nebraska containing several sand-gravel and crushed limestone-sand gravel combinations, one of which is being considered for use as aggregate in concrete in Milford Dam, were studied using petrographic and X-ray test methods. Eight of these contained crushed limestone and natural siliceous aggregate; three contained siliceous ('sand-gravel') aggregate only. The concretes ranged in age from 6 to 53 years. The cores were first examined visually; then prisms of selected cores were cut, stored in and over water and in air, and aggregate in all the cores contained opal, which is the most reactive form of silica known. All the cores except the youngest showed evidence of alkali-silica or alkali-carbonate reaction or of both. Samples cut from the youngest core showed more expansion under laboratory exposure than samples cut from any other core. Only one of the cores showed clear-cut evidence of damage due to reaction. It was from a poorly drained section of road pavement, placed in 1929; most of the other cores were from above-grade structures. All of the limestones except the Towanda were porous and contained disseminated, fine-grained reactive (pozzolanic) silica. No evidence of any chemical reaction involving the siliceous natural aggregates other than the alkaki-silica reaction was found. The beneficial effects of limestone coarse aggregate appear to derive from their pozzolanic character.

Descriptors :   (*DAMS, CONSTRUCTION MATERIALS), (*CONCRETE, CHEMICAL ANALYSIS), (*CONSTRUCTION MATERIALS, STRUCTURAL PROPERTIES), SAMPLING, SAND, GRAVEL, LIMESTONE, CHEMICAL EQUILIBRIUM, AGING(MATERIALS), DEGRADATION, KANSAS

Subject Categories : Polymer Chemistry
      Civil Engineering

Distribution Statement : APPROVED FOR PUBLIC RELEASE