Concrete International
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Featured Articles
  August 2015  
 
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Concrete International August 2015 No. 8 Complete Issue
Concrete International August 2015 No. 8 Complete Issue

Slag Cement Association 2014 Project of the Year Awards
The Slag Cement Association (SCA) presented the 2014 Project of the Year Awards during the meeting of ACI Committee 233, Ground Slag in Concrete, at The ACI Concrete Convention and Exposition—Spring 2015 in Kansas City, MO.

2015 Concrete Cylinder Competition Mexico
The Fifth National Concrete Cylinder Competition was held at the Universidad de Guanajuato on May 2, 2015.

Prescriptive Specifications
About 10 years ago, the National Ready Mixed Concrete Association (NRMCA) initiated an effort aimed at transforming concrete specifications from prescriptive to more performance based. In 2014, NRMCA’s Research Engineering and Standards committee conducted a survey among concrete producer members on 15 prescriptive requirements commonly seen in mixture specifications. The requirements were ranked and the top five were further evaluated using 150 recent project specifications. The Specification in Practice (SIP) series was prepared to discuss the requirements and suggest alternative requirements based on performance criteria. The SIP series is available on the NMRCA website. The first five in the series are included in this issue of CI.

Improving the Quality of Concrete Testing
There is a concern among ready mixed concrete producers that quality assurance testing is not consistently performed in accordance with ASTM standards. All project participants are affected by substandard testing practices, as false-negative or false-positive test results can lead to rejections of good concrete loads or acceptance of bad quality concrete, respectively. The article makes recommendations for evaluating and improving the quality of concrete testing, and it describes a program that allows testing agencies and their technicians to assess their performance relative to their peers.

Performance-Based Proportioning
Many concrete mixtures are proportioned based on standard, previously used “recipes,” and/or on prescriptive specifications that define limits on the type, amount, and proportions of mixture components. Costs and environmental impacts may therefore be suboptimal. Performance-based specifications allow the development of mixtures that have been adjusted for local materials and that meet specific owner and contractor requirements. A recently developed performance-based mixture proportioning method is described. The method includes evaluation and selection of the paste and aggregate systems as well as analysis of interactions between the two systems. An Excel® spreadsheet tool is available to help users apply the method.

SIP 1 – Limits on Quantity of Suplementary Cementitious Materials

SIP 2 – Limits on Water-Cementitious Materials Ratio (w/cm)

SIP 3 – Minimum Cementitious Materials Content

SIP 4 – Restrictions on Type and Characteristics of Fly Ash

SIP 5 – Restrictions on Aggregate Grading

ACI/CRSI Adhesive Anchor Installer Certification Adopted at Los Alamos National Laboratories
In May 2015, the Rocky Mountain Chapter – ACI was contracted by Los Alamos National Laboratories to execute ACI/CRSI’s Adhesive Anchor Installer certification program for 60 of their employees. Running 60 candidates through the program presented some logistical and staffing challenges that were solved by organizing two, 2-day program sessions. The program is described, and client feedback is noted.

ACI Launches New Marketing Toolkit
On-demand resources are available to effectively communicate about ACI’s products and services—and its vision

Knowledge to Practice: ACI Foundation
Concrete Research Council Announces New Funding Protocol: $50,000 per Project

Concrete Q&A
Influence of Aggregate Size on Concrete Strength and Shrinkage

 


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