In recent years, highway agencies and constructors have used improved construction techniques and materials for better pavement quality. However, newly constructed portland cement concrete pavement surfaces are not always being built to the desired level of ride quality; thus, there is a need for an improved smoothness specification to insure the best riding quality. This paper documents the development and evaluation of end-result smoothness specifications for portland cement concrete pavements in Texas. Based on available equipment and prior studies, the California Profilograph was selected as the instrument for use in developing the specification. Because there are several types of California profilographs, the study team compared two instruments by two different manufacturers. This paper presents the results of this comparison, along with a methodology for defining a recommended specification.

In-place testing is used to estimate the compressive strength of concrete in a structure by measuring another related property. A strength relationship is used to convert the in-place test results to an estimate of the compressive strength. Statistical methods are needed for reliable estimates of in-place strength. Such methods should account for the uncertainties in the measured property, the uncertainty of the strength relationship, and the variability of the in-place concrete. Standard statistical procedures for dealing with these uncertainties have not yet been adopted in North American practice. Recommendations are provided for developing the strength relationship, and a reliable, easy-to-use approach is presented to estimate in-place characteristic strength.

Recently, in Japan, application of the roller compacted dam concrete (RCD) method has increased in the construction of concrete gravity dams. The concrete for the RCD method (RCD concrete) features a very stiff consistency with low water content, which enables the use of a vibration roller for compaction. Most of the cement used so far for RCD concrete has used a combination of fly ash with moderate heat portland cement. However, the supply of high-quality fly ash for use in concrete has recently lessened in Japan. One admixture replacing fly ash is granulated blast furnace slag. In this study, properties of RCD concrete made with slag cement featuring blends of moderate heat portland cement and granulated blast furnace slag were examined. The effect of fineness of the individual slag cement components on compressive strength and adiabatic temperature rise were studied. The unit cement content in the concrete was 120 kg/m 3. The maximum size of the coarse aggregate was 150 mm. The results show that concrete with moderate low-heat slag cement can provide the same or better performance as fly ash cement concrete by employing a rational combination of fineness and slag content. Also, the advantages of slag cement at longer ages were confirmed. The results obtained in this study are now being applied to an actual dam construction.

A reliability-based approach is used to recommend allowable edge loads for precast hollow core slabs. Full-scale test results are used to predict the statistical parameters of the resistance at the edge. The study indicated that the allowable load is a function of dead-to-live load ratio and concrete strength. The analysis is extended to include system reliability of the whole slab due to different failure modes. The failure modes include flexure at midspan and total shear at the ends, in addition to local failure at the edge. The system modeling is composed of a series system made up of three partially correlated elements. A numerical example is also included for illustration. The approach will help engineers make a rational selection of allowable edge loads that occur around large floor openings.

For some years, the Ministry of Transportation of Ontario (MTO) and the Ready-Mixed Concrete Association of Ontario (RMCAO) have separately run programs to measure the reproducibility of test results between commercial laboratories. The comparative test results were made on standard cured 150 mm diameter by 300-mm test cylinders. The reproducibility of test results obtained between testing laboratories on nominally identical test specimens is an important factor in the statistical evaluation of test data. Unless the reproducibility is good, concrete mixes need to be overdesigned, with resulting higher costs. In addition, poor reproducibility between laboratories increases the probability that some test cylinders will fail to meet specified strength requirements. Even if the concrete in the structure represented by these results probes to be adequately strong, disruption and economic loss result from the publication of erroneous results. This paper analyzes the data obtained by the RMCAO, derives repeatability and reproducibility indexes, and discusses their economic consequences. Some data from the MTO program are also reported. Recommendations for improvements are made.