International Concrete Abstracts Portal

Editor: Chris Ramseyer

With the exception of #9, these Papers were presented at: ACI National Convention, Fall 2012 Toronto, Canada. In the Technical Session Shrinkage Compensating Concrete – Past, Present, and Future Part 1 and Part 2.

This publication is dedicated to Edward K. Rice

Ed Rice has been involved in Shrinkage Compensating Concrete from its inception. As co-founder and President of T.Y. Lin and Associates from 1952 through 1970 Ed Rice promoted the novel use of concrete and concrete systems. As early as 1956 T.Y. Lin and Ed Rice provided the necessary funding for fundamental research by Alex Klein on expansive cements. This research led to the development of the Chemically Prestressed Concrete (CPC) co that was primarily in the pipe and roof slab business. In 1965 under Ed Rice’s direction as Chairman of CPC, Ed licensed Kaiser to run the first full scale burn at their Cushenberry cement plant and commercially produce the first shrinkage compensating concrete clinker in the world.

In the fifty years since the first production run of shrinkage compensating cement Ed Rice has consistently worked to advance concrete cement technology. He holds 22 US patents in the field of concrete and building technology. For the last forty years Ed Rice has led CTS Cement Manufacturing Co., the largest producer of shrinkage compensating cement in North America. Often Ed Rice worked behind the scenes helping to promote shrinkage compensating concrete and the work of younger engineers. Ed Rice has been a consistent and steady advocate for both increased research on the behavior of shrinkage compensating cements; and increased use of shrinkage compensating concrete to produce stable and durable concrete structures.

Note: The individual papers are also available. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP-307

Samples of Type K shrinkage-compensating cement from all 17 mills producing that cement in 1974 were obtained and evaluated for compliance with the specification that was proposed at that time for these types of cements. The cements were also evaluated for specific gravity, fineness, heat of hydration, and expansion and drying shrinkage in mortars. An X-ray diffraction analysis was also made for each cement in an attempt to compare cements to note significant differences in composition or relative amounts of constituents. A standard concrete mixture was also made with all the cements and evaluated for air content, slump, compressive strength, expansion, and drying shrinkage. The results from these evaluations are revisited. The application of the 1974 proposed specification called attention to several short-comings in that specification.

This short work details the history of Type K shrinkage compensating cement.

This paper reexamines the authors’ experimental results on the dimensional stability of concrete slab-on-ground under a variety of environmental conditions. The experiments considered the dimensional properties of concrete slab materials using both Demec targets and vibrating wire strain gages. Realistic slab-on-ground sections were investigated in this study in that the concrete slabs were exposed to a controlled environment on the top surface and to actual ground moisture on the bottom surface. The concrete materials tested were normal Portland cement concrete (PCC), high strength concrete (HSC), concrete with shrinkage reducing admixtures (SRA), and concrete with calcium sulfoaluminate cement (CSA). The compiled database contains: 1) standard concrete material test results; 2) joint movements in concrete slab-on-ground; and 3) internal relative humidity and temperature through the slab-on-ground depth. The experimental results revealed that CSA was quite stable with little long-term shrinkage/cracking or warping, whereas PCC and HSC had continuing crack growth during 600 days of curing. The SRA exhibited a modest reduction in shrinkage/crack at the early stage, and while this decrease extended for the length of the testing no further decrease in the shrinkage growth or sectional stability was noted when compared to PCC at the end of 2 years. Evaluation of the vibrating wire strain gage method of measuring long term concrete shrinkage was found to be less prone to user bias and more accurate than the Demec target method or the ASTM C157 method.

Shrinkage compensating concrete is one of the most common products currently used to mitigate the influence of drying shrinkage cracking in slabs, beams and other structural components. Type K expansive concretes have proved effective for prevention of structural and aesthetic damage due to tensile cracking in many modern applications. However, the ACI 223R-10 technical guide still indicates that a shrinkage compensating slab cannot expand adequately if it is surrounded on all sides by mature reinforced concrete. The objective of this project was to investigate whether the presence of a stiff external restraint condition, which may be provided by adjoining concrete, prevents a Type K expansive concrete slab from compensating for shrinkage. To investigate this behavior, the field condition of a slab-to-slab interaction was simulated using a steel restraint system with varying degrees of stiffness and amounts of Type K expansive cement component. Test frames were instrumented to evaluate the force and displacement responses of the Type K expansive concrete to the different boundary conditions provided by varying the steel restraint system. The results of this investigation support a conclusion contrary to that currently found in the ACI 223R-10 guiding document. This study concludes that a Type K expansive cement concrete does not suffer a severe reduction in shrinkage compensation in the presence of a very stiff boundary condition.