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The main objective of this experimental and analytical research project was to develop maturity-based guidelines for early opening-to-traffic of concrete pavements in the state of Indiana. Currently, the Indiana Department of Transportation (INDOT) specifies that pavements can be opened to traffic when the concrete reaches the strength of at least 3.8 MPa (550 psi). During this study modulus of rupture (MOR) and maturity data were collected and strength gain characteristics were analyzed. Also, fatigue experiments were performed at different stress levels and ages. Based on the experimental results, modulus of rupture of concrete was correlated with corresponding fatigue life for a specific age. The maturity data was then linked with fatigue results through flexural strength correlation. A safe early opening age was determined based on design load used by INDOT and specifications for allowable repetitions. The results of this research should be useful to both INDOT and contractor by allowing for quantification of the impact of early opening on performance of the pavement. In addition, early pavement opening will reduce the cost to the travelling public by reducing construction time and improving safety in the construction zone. .

This research was based on a two-part basic research investigation studying the effects of cement paste-aggregate interfaces (or interfacial transition zones-HZ) on strength and durability of concrete. Part I dealt with the theoretical study and Part II dealt with the experimental. Part I, the theoretical part, illustrates the effect of ITZ on the concrete properties by assuming its elastic moduli to be varied continuously in the region. A four-phase composite model is employed and three functions are chosen to model the moduli variation in the ITZ. A theoretical solution for an n-layered spherical inclusion model is used to estimate the overall effective moduli of the modified four-phase model. The influence of material and geometric characteristics of the ITZ, as well as that of the aggregate on the overall effective moduli is investigated. The effects of three different moduli variations in ITZ on the overall moduli are compared. Their potential application is discussed. Finally, by comparing the prediction of the proposed models to a set of data on mortar, it is found that the elastic modulus at the interface is about 20-70% lower than that in the bulk paste for portland cement mortar, and 1040% lower for silica fume mortar. Part II, the experimental part, illustrates the relationship between the ITZ microstructure and the mechanical properties of the concrete. The mechanical properties studied included the dynamic modulus of elasticity, dynamic shear modulus, logarithmic decrement of damping, flexural tensile strength, and compressive strength. In addition, the effects of changing the water-tocementitious material ratio by mass, aggregate type, volume fraction of aggregate, and silica fume substitution, on these properties were investigated. A criterion based on water quantity and the specific surface area of aggregate by mass in a mixture was developed to eliminate biased date from the analysis process. This criterion was used to detect mixing and compaction p

The objective of this study was the evaluation of frost resistance of concrete bridge decks with stay-in-place galvanized steel deck forms. The evaluation included specific aspects related to the potential for D-cracking in concrete bridge decks with these forms. The experimental program has been set up so that the real parameters of the bridge deck overlays and the environmental conditions could have been modeled. The program included freezing-and-thawing testing of large concrete slab specimens (22 ¼” x 17 ¼” x 5 ¼”) situated in a computer-controlled environmental chamber and of small specimens (3” x 4” x 12”) immersed in water situated in a freezing-and-thawing machine. The following tests have been carried out: relative ultrasonic pulse velocity, expansion of small specimens, weight changes of small specimens. Relative humidity and moisture content have been measured for controlling the moisture state of concrete. The results of this study suggest that corrugated steel deck forms may promote the damage of concrete made with D-cracking coarse aggregate due to freezing-and-thawing action. The coarse D-cracking aggregate may by itself cause cracking and scaling of concrete bridge decks with or without steel deck forms.

One of the most economic methods of bridge deck construction consists of prestressed concrete deck panels used in stay-in-place forms in conjunction with the cast-in-place concrete topping instead of the traditional monolithic roadway deck slabs. The performance of this type of deck as a composite unit is only possible if the horizontal shear stress resulting from bending of the deck if effectively transferred across the interface of the two elements. It is assumed that horizontal shear stresses are transmitted across the interface due to bond between the precast panel and cast-in-place concrete acting in conjunction with the horizontal shear connectors provided across the interface. Presently the Indiana Department of Transportation requires a minimum of 20 shear connectors in (1.27 to 1.91 mm) total amplitude deformations is specified instead of a raked finish with a total amplitude of 0.25 in. (6.35 mm) because of the reduced 2.5 in (63.5 mm) thickness of the panels used in Indiana. This study focuses on the evaluation of the horizontal shear strength across a broom finished interface. Experiments were undertaken on six precast prestressed deck panels with composite cast-in-place concrete topping. All the specimens were 8 ft. x 3ft. (2.4 m x 2.4 m) and 2.5 in. (63.5 mm) thick precast prestressed panels were 5.5 in (140 mm) topping slab. Specimens 1 and 5 had no shear connectors and specimens 2, 3 and 6 had four shear connectors across the interface. Specimen 4 had four shear connectors and the top of the precast panel was sprayed with a bond breaking agent (form oil) to eliminate chemical bonding between the precast panel and cast-in-place concrete topping. The test results indicated that shear connectors are not required to achieve adequate composite action at service and ultimate load levels in panels with broom finished top surface. This finding is limited to situations where the nominal average shear stress does not exceed 115 psi. A minimum of 4 shear connec

The objective of this research is to evaluate the use of the November 8, 1991 SHRP C-206 report entitled, “Packing Handbook – A Guide to the Optimal Gradation of Concrete Aggregates”. The purpose of the Packing Handbook is to determine the optimal combination of fine and coarse aggregates for concrete from available aggregate sources. Through the use of tables provided in the Packing Handbook, and given sources with known aggregate gradations and void contents, the relative proportion of each aggregate (coarse and fine) is obtained. Concretes made using the Packing Handbook recommendations of aggregate proportioning were compared to concretes used on various INDOT pavement projects. Field proportioned concretes were replicated in the laboratory. The only difference between field mixtures, the field mixtures replicated in the laboratory, and the Packing Handbook laboratory mixtures was the percent of coarse aggregate in the mixes. Other proportions were held constant, i.e. cement content, w/c*fa, and the use of admixtures. The Packing Handbook was evaluated based on the comparison of engineering properties of the field control mixtures and the Packing Handbook mixtures. Packing Handbook mixes were harsh and will achieve little or no cost reductions or quality improvements if implemented for field use. Copies of this document are available on CD-ROM from INDOT Division of Research, West Lafayette, IN.

The demolition of buildings and highway pavements in the State of Indiana generates a considerable amount of waste materials. The disposal of these materials causes strain on the existing landfills which are rapidly approaching their full capacity. This study is a synthesis of the information on the use of concrete recycled from pavements and building rubble for use in the Indiana highway system. Test results have shown that recycled pavement concrete made chiefly from broken-up and crushed old concrete aggregate is as good as concrete made from virgin aggregate, and sometimes better. The aggregates made from recycled concrete can be used in other applications besides structural pavement. These include shoulder pavement, road surfacing, fill soil stabilizer, pavement base, sub-base material, and econocrete as well as several other applications which are still being tested. The use of recycled fine aggregates should be carefully monitored and should not be used for the development of medium to high-strength concrete. Fines should also not be used in the sub-base, embankment under abutments, and locations surrounding filters. Economic considerations are the primary reasons for recycling the old portland cement concrete as aggregate in new portland cement concrete pavements, although environmental benefits often are derived as well and may become more important in the future. After analyzing other states findings and conclusions, it is recommended that the Indiana Department of Transportation continue recycling portland cement concrete from pavements and proceed with the implementation of a program for recycling concrete from buildings rubbles.