This report describes a laboratory evaluation of the physical characteristics of shrinkage compensating cements when additives are used. Two admixtures were studied, Dow Corning 777B, a reactive polysiloxane, which increases the durability or resistance to weathering, and Sika Set, a low-shrinkage, final set accelerator. The concrete used was a standard Minnesota Highway Department bridge deck design mix (3Y43).
The two additives generally improved the physical characteristics of the ChemComp shrinkage compensating cement but greatly reduced the durability of the concrete in the freeze-thaw tests.
It is recommended that Sika Set and Dow Corning 777B not be used in ChemComp cement concrete due to the low durability which results. The use of other additives with ChemComp cement should be evaluated before use in the field.
An experimental field project was constructed in southeastern Minnesota 1965 to evaluate the effectiveness of stabilizing the upper portion of a silty subgrade with two different bituminous materials, RT-6 and MC-2. The project contained six sections in which the upper 6 inches of the subgrade was stabilized with bituminous material and capped with 3 or 5 inches of gravel. Two unstabilized control sections were designed with a 7-in. gravel base. The best performing stabilized section was on a par with the control sections, but was much more costly. The relative performance of the stabilized sections could be related to results from laboratory tests conducted on similar soil-bituminous mixtures.
This study was conducted to determine the construction feasibility and the requirements that are needed for a roadbed which would meet the increased demands of traffic volumes and loads that are to be expected in the future. To accomplish this the construction of a portland cement concrete pavement over bituminous-treated and cement-treated bases was monitored and certain tests which supposedly relate to long-term performance were conducted. Standard granular base sections were also included for comparison purposes.
During 1969, 1970 and 1971 density data were obtained on bituminous wearing courses that were being constructed on several Minnesota trunk highways. Data were collected and analyzed from randomly selected locations on five bituminous surfacing projects. A statistical analysis was also performed on results from eleven other bituminous projects and on laboratory test results. Variation was determined from these data by computing the mean and standard deviation to reveal existing variability in acceptable construction of bituminous wearing courses. The results were used to evaluate present specifications and to develop a new acceptance sampling plan. The plan is based on statistical concepts that will define the degree of acceptable variation upon which decisions can be made with an established degree of confidence. Proposed statistical specifications are presented.
During 1969, 1970 and 1971 density data were obtained on bituminous wearing courses that were being constructed on several Minnesota trunk highways. Data were collected and analyzed from randomly selected locations on five bituminous surfacing projects. A statistical analysis was also performed on results from eleven other bituminous projects and on laboratory test results. Variation was determined from these data by computing the mean and standard deviation to reveal existing variability in acceptable construction of bituminous wearing courses. The results were used to evaluate present specifications and to develop a new acceptance sampling plan. The plan is based on statistical concepts that will define the degree of acceptable variation upon which decisions can be made with an established degree of confidence. Proposed statistical specifications are presented.
During 1969, 1970 and 1971 density data were obtained on bituminous wearing courses that were being constructed on several Minnesota trunk highways. Data were collected and analyzed from randomly selected locations on five bituminous surfacing projects. A statistical analysis was also performed on results from eleven other bituminous projects and on laboratory test results. Variation was determined from these data by computing the mean and standard deviation to reveal existing variability in acceptable construction of bituminous wearing courses. The results were used to evaluate present specifications and to develop a new acceptance sampling plan. The plan is based on statistical concepts that will define the degree of acceptable variation upon which decisions can be made with an established degree of confidence. Proposed statistical specifications are presented.
During 1969, 1970 and 1971 density data were obtained on bituminous wearing courses that were being constructed on several Minnesota trunk highways. Data were collected and analyzed from randomly selected locations on five bituminous surfacing projects. A statistical analysis was also performed on results from eleven other bituminous projects and on laboratory test results. Variation was determined from these data by computing the mean and standard deviation to reveal existing variability in acceptable construction of bituminous wearing courses. The results were used to evaluate present specifications and to develop a new acceptance sampling plan. The plan is based on statistical concepts that will define the degree of acceptable variation upon which decisions can be made with an established degree of confidence. Proposed statistical specifications are presented.
This study was initiated to develop and evaluate a rating system which would be used to help determine the need for resurfacing pavements. In 1965, the Minnesota Highway Department began an accelerated program of highway resurfacing. Because the amount of money available wasn't sufficient to include in the program all the roads which were deemed to be in need of resurfacing, it became necessary to chose the roads which needed resurfacing the most.
The rating system described in this report was originally developed by the Research Section in the spring of 1966. At first it only included concrete pavements but since has been expanded to include both bituminous and bituminous overlaid concrete pavements also. Although some revisions
in the original rating system have been made, the rating system has been used to rate roads in Minnesota every year since 1966.
During the fall of 1969 transverse cracks were sealed in a 13-mile section of bituminous pavement. Five hot-poured rubber asphalt sealers, three tack coat materials for priming the crack sidewall, a bond breaker and 40 different application procedures were used. Test sections were established to evaluate the materials and procedures. Field surveys were conducted to determine the amount of footage failed. Reference pins were also installed to measure crack movement. The field results were used to evaluate the materials and procedures incorporated in the study program.
