Friday Facts, September 24, 2010, Vol. 72

Bureau of Nutrition and Health Promotion part of the Iowa Department of Public Health produces of weekly newsletter about the Iowa WIC Program for the State of Iowa citizen.

A Study of the Reliability of the ASTM C-666 Freeze-Thaw Test, MLR-72-01 and R-252, 1972

The Iowa State Highway Commission purchased a Conrad automatic freeze and thaw machine and placed it in operation during October 1961. There were a few problems, but considering, the many electrical and mechanical devices used in the automatic system it has always functioned quite well. Rapid freezing and thawing of 4"x4"xl8" concrete beams has been conducted primarily in accordance with ASTM C-29l (now ASTM C-666 procedure B) at the rate of one beam per day. Over 4000 beams have been tested since 1961, with determination of the resulting durability factors. Various methods of curing were used and a standard 90 day moist cure was selected. This cure seemed to yield durability factors that correlated very well with ratings of coarse aggregates based on service records. Some concrete beams had been made using the same coarse aggregate and the durability factors compared relatively well with previous tests. Durability factors seemed to yield reasonable results until large variations in durability factors were noted from beams of identical concrete mix proportions in research projects R-234 and R-247. This then presents the question "How reliable is the durability as determined by ASTM C-666?" This question became increasingly more important when a specification requiring a minimum durability factor for P.C. concrete made from coarse aggregates was incorporated into the 1972 Standard Specification for coarse aggregates for concrete.

Design Methodology for Corrugated Metal Pipe Tiedowns, HR-332, Phase 1, 1993

Questionnaires were sent to transportation agencies in all 50 states in the U.S., to Puerto Rico, and all provinces in Canada asking about their experiences with uplift problems of - corrugated metal pipe (CMP). Responses were received from 52 agencies who reported 9 failures within the last 5 years. Some agencies also provided design standards for tiedowns to resist uplift. There was a wide variety in restraining forces used; for example for a pipe 6 feet in diameter, the resisting force ranged from 10 kips to 66 kips. These responses verified the earlier conclusion based on responses from Iowa county engineers that a potential uplift danger exists.when end restraint is not provided for CMP and that existing designs have an unclear theoretical or experimental basis. In an effort to develop more rational design standards, the longitudinal stiffness of three CMP ranging from 4 to 8 feet in diameter were measured in the laboratory. Because only three tests were conducted, a theoretical model to evaluate the stiffness of pipes of a variety of gages and corrugation geometries was also developed. The experimental results indicated a "stiffness" EI in the range of 9.11 x 10^5 k-in^2 to 34.43 x 10^5 k-in^2 for the three pipes with the larger diameter pipes having greater stiffness. The theoretical model developed conservatively estimates these stiffnesses.

Wapello County, Township 72 North Range 12 West

Des Moines River Plat Maps.

Wapello County, Township 72 North Range 13 West

Des Moines River Plat Maps.

Wapello County, Township 72 North Range 14 West

Des Moines River Plat Maps.

Wapello County, Township 72 North Range 15 West

Des Moines River Plat Maps.

Monroe County, Township 72 North Range 16 West

Des Moines River Plat Maps.

The Annals of Iowa, Summer 2013, Vol. 72, no. 3

A quarterly journal of Iowa authors and their works produced by State Historical Society of Iowa.

The Annals of Iowa, Fall 2013, Vol. 72, no. 4

A quarterly journal of Iowa authors and their works produced by State Historical Society of Iowa.

The Annals of Iowa, Winter 2013, Vol. 72, no. 1

A quarterly journal of Iowa authors and their works produced by State Historical Society of Iowa.

The Annals of Iowa, Spring 2013, Vol. 72, no. 2

A quarterly journal of Iowa authors and their works produced by State Historical Society of Iowa.