Rudolph N. Kraus

PRECAST CONCRETE PRODUCTS USING INDUSTRIAL BY-PRODUCTS

This work aimed to help establish the use of high volumes of fly ash, bottom ash, and used foundry sand in manufacture of precast molded concrete products such as wet-cast concrete bricks and paving stones. ASTM Class F fly ash was used as a partial replacement for 0 (reference), 25, and 35% of portland cement. Bottom ash combined with used foundry sand replaced 0, 50, and 70% of natural sand. Tests for compressive strength, freeze-thaw resistance, drying shrinkage, and abrasion resistance were conducted on the wet-cast concrete masonry units manufactured at a commercial manufacturing plant. It was concluded that all wet-cast bricks could be used for both exterior and interior walls in regions where freezing and thawing is not a concern, and for interior walls in regions where freezing and thawing is a concern. No wet-cast paving-stone mixtures, including the reference mixture, met all ASTM requirements for paving stones.

Long-Term Performance of High-Volume Fly Ash Concrete Pavements

This investigation was undertaken to evaluate the long-term performance of concrete pavements made with high volumes of Class F and Class C fly ash (FA). Six different mixtures, three mixtures with Class C fly ash up to 70% cement replacement and three mixtures with Class F fly ash up to 60% cement replacement, were used. Long-term performance tests were conducted for compressive strength, resistance to chloride-ion penetration, and density using specimens from in-situ pavements. Long-term results showed greater pozzolanic strength contribution of Class F fly ash relative to Class C fly ash. Generally, based upon long-term data, mixtures containing Class F fly ash exhibited higher resistance to chloride-ion penetration relative to mixtures containing Class C fly ash. Compressive strengths of core specimens taken from in-situ pavements ranged from 45 to 57 MPa (6,600 to 8,300 psi) at seven to 14 years of age. The highest long-term compressive strength (57 MPa, 8,300 psi) was achieved for the high-volume fly ash mixture incorporating 67% Class F fly ash at the age of 7 years. Visual observations (in 2000) revealed that the pavement sections containing high volumes of Class F fly ash (40 to 67% FA) performed well in the field with only minor surface scaling. All other pavement sections have experienced very little surface damage due to the scaling.

Influence of Types of Coarse Aggregates on the Coefficient of Thermal Expansion of Concrete

The coefficient of thermal expansion (CTE) was determined for a typical concrete-paving mixture made with six different types of coarse aggregates belonging to the basic class of glacial gravel, quartzite, granite, diabase, basalt, and dolomite. The CTE, compressive strength, and splitting tensile strength of fifteen different concrete mixtures were determined at the age of 28 days. Two parameters, CTE and splitting tensile strength, are the basic input in AASHTOs new mechanistic-empirical pavement design method. The study revealed a no- ticeable variation in the values of the CTE of concrete with different types of aggregates. Concrete with quartzite aggregate had the highest value of the CTE followed by dolomite, glacial gravel, granite, and diabase or basalt. The estimated value of the splitting tensile strength of concrete, considering its compressive strength and using AASHTOs Mechanistic-Empirical Pavement Design Guide for Level 2 design of concrete pavements was discovered to be significantly lower (17-31%) than its actual experimentally determined value. DOI: 10.1061/ (ASCE)MT.1943-5533.0000198.

Design and Testing Controlled Low-Strength Materials (CLSM) Using Clean Coal Ash

The major objective of this project was to develop mixture proportions for controlled low-strength material (CLSM) using clean coal ash obtained from atmospheric fluidized bed combustion (AFBC). A clean coal ash is defined as the ash derived from SO{sub x} and NO{sub x} control technologies. The specific ashes used for this project were: (1) circulating fluidized bed boiler fly ash and bottom ash and (2) stoker-type boiler fly ash and bottom ash. These two coal ash samples were characterized for physical and chemical properties. Chemical properties and water leaching tests were also performed on the hardened CLSM. Many initial CLSM mixtures were developed by blending the two types of ash. Tests conducted on the final three selected CLSM mixtures included compressive strength, bleeding, setting and hardening, settlement, length change of hardened CLSM, permeability, mineralogy, and chemical water leach testing. Results show that acceptable CLSM material can be developed by blending the fluidized bed boiler ash with the stoker boiler ash. Recommendations for a pilot scale manufacturing application of the three CLSM mixtures were made based upon the lab test results.

Decing Salt-Scaling Resistance: Laboratory and Field Evaluation of Concrete Containing up to 70 % Class C and Class F Fly Ash

Laboratory mixtures, pilot mixtures, and field construction mixtures were made to evaluate salt-scaling resistance of concrete incorporating large amounts of either Class C fly ash obtained from several different sources or Class F fly ash. The laboratory mixtures that incorporated Class C fly ash up to a fly ash to cementitious materials ratio (FA/Cm) of 60 % by mass exhibited very slight to moderate scaling. Results from the pilot mixtures indicate that it is possible to produce structural-grade, salt-scaling resistant concrete using up to 56 % Class C fly ash. Specimens of a field mixture containing 50 % Class C fly ash showed moderate to severe scaling, and specimens of a field concrete with 40 % Class F fly ash showed slight to moderate scaling. These field mixtures exhibited satisfactory salt-scaling resistance in actual pavements. Comparisons of strength and scaling results suggest that it would be beneficial to allow sufficient time for high-volume fly ash concrete to develop strength before it is subjected to salt-scaling actions.

Effects of Fly Ash and Foundry Sand on Performance of Architectural Precast Concrete

This research was conducted to establish the effects of fly ash and used foundry sand on strength and durability of concrete. Two series (Series 1 and Series 2) of experiments were performed. All concrete mixtures were produced for and at the production plant of an architectural precast concrete products producer. Concrete mixtures produced were used in manufacture of precast concrete panels. Tests were performed with normal and air-entrained fly ash concrete. Concrete test specimens were evaluated for compressive strength, abrasion resistance, salt-scaling resistance, freezing and thawing resistance, and chloride-ion penetration resistance. On the basis of strength and durability evaluations, it was concluded that both nonair and air-entrained concrete mixtures developed in this investigation are appropriate for manufacture of high-quality, high-durability architectural precast concrete using used foundry sand and fly ash.

Use of Residual Solids from Pulp and Paper Mills for Enhancing Strength and Durability of Ready-Mixed Concrete

This research was conducted to establish mixture proportioning and production technologies for ready-mixed concrete containing pulp and paper mill residual solids and to study technical, economical, and performance benefits of using the residual solids in the concrete. Fibrous residuals generated from pulp and paper mills were used, and concrete mixture proportions and productions technologies were first optimized under controlled laboratory conditions. Based on the mixture proportions established in the laboratory, prototype field concrete mixtures were manufactured at a ready-mixed concrete plant. Afterward, a field construction demonstration was held to demonstrate the production and placement of structural-grade cold-weather-resistant concrete containing residual solids.

Mechanical Properties and Durability of Concrete Pavements Containing High Volumes of Fly Ash

This study examines the performance characteristics of concrete pavements made with high volumes of Class F and Class C fly ash. Three mixture proportions with Class C fly ash up to 70% cement replacement and 3 mixtures with Class F fly ash up to 67% cement replacement were used. Tests were conducted for compressive strength, resistance to chloride-ion penetration, and density using specimens from in-situ pavements. Results indicate better pozzolanic strength contribution and higher resistance to chloride-ion penetration for concrete mixtures made with Class F fly ash relative to that made with Class C fly ash. Compressive strengths of core specimens taken from in-situ pavements ranged from 45-57 MPa. Field performance data vs. lab evaluation data for scaling is also presented.

MANUFACTURE OF MASONRY PRODUCTS CONTAINING LARGE AMOUNTS OF FLY ASH

This investigation was conducted to establish a database for manufacturing of concrete masonry products incorporating high volumes of ASTM Class F fly ash. A total of 15 mixture proportions for bricks, blocks, and paving stones, including reference mixture for each type of masonry product, were proportioned. The fly ash content was varied from 20 to 50% for brick and block mixtures, and from 15 to 30% for paving stone mixtures. All masonry products were tested for compressive strength, density, absorption, freezing and thawing resistance, drying shrinkage, and abrasion resistance. Test results indicated that bricks and blocks with up to 30% fly ash are suitable for use in both cold and warm climates. Other brick and block mixtures containing up to 50% fly ash were appropriate for building interior walls in cold regions and both interior and exterior walls in warm regions. None of the paving stone mixtures, including the control mixture, strictly conformed to all ASTM requirements. However, all the paving stone mixtures with and without fly ash are suitable for normal construction applications.

Properties of Flowable Self-Compacting Slurry Using Quarry By-Products and Ponded CCPs

This paper reports the properties of two series of flowable self-compacting slurry (SCS). In Series 1, a limestone quarry by-product, fine crushed sand (FCS), and ponded-CCPs were used. For Series 2, standard concrete sand and ponded-CCPs were used. For Series 1, five mixtures and for Series 2, six mixtures of flowable SCS were made. Ponded-CCPs and limestone quarry FCS content of the mixtures was expressed as a percentage of total fines. For Series 1 SCS mixtures, ponded-CCPs content was 100, 67, 53, 35, and 0%, and limestone quarry FCS content was 0, 33, 47, 65, and 100%, respectively. In Series 2 SCS mixtures, ponded-CCPs content was 100, 81, 60, 40, 20, and 4%, and standard concrete sand content was 0, 19, 40, 60, 80, and 96%, respectively. For both series of flowable SCS mixtures, tests were performed for flow, density, settlement, compressive strength, and permeability. Setting and hardening, bleeding, and ambient air and CLSM temperatures were also recorded.