Concrete pavement with the preset strength safety level for highways and streets

Abstract

Concrete pavement of highways and streets is designed with preset strength safety level determined depending on the volumes of truck traffic. The choice of this level is based on the analysis of test results of thousands precast and prestressed structural members. Strength safety of pavement is equivalent to safety of design flexural strength of concrete estimated as a part of modulus of rupture. Thickness design of pavement with the preset strength safety level allows more complete utilization of flexural strength of concrete than that provided by the current design practice. If thickness of pavement is controlled by results of fatigue analysis, it means reduction of thickness of pavement by 8-10% as compared with that provided by the thickness design of these pavements according to Portland Cement Association Engineering Bulletin EB109P. It can be applied to any other methods of thickness design of concrete pavement as well as for PCA method.

1 . Concrete pavement for highways and streets of the preset strength safety level with the thickness determined by results of fatigue analysis which is less by 8-10% than the thickness of this pavement provided by the current Portland Cement Association design procedure due to more complete utilization of flexural strength of concrete than that provided by the current Portland Cement Association design practice of utilization of this strength for carrying out of fatigue analysis of pavement in the framework of said design procedure or with the use of other methods of fatigue analysis according to the requirements of the customer, more complete utilization of flexural strength of concrete considered as a random value means the use of values of modulus of rupture exceeding the mean value of flexural strength for thickness design of pavement, mix design of concrete of pavement being determined by value of modulus of rupture (MR) required by the thickness design according to said design procedure, fatigue analysis of pavement is carried out with consecutive use of few values of modulus of rupture of concrete (MR) considered corresponding to the one value of specified compressive strength of this concrete f c ′, the least of these few values just corresponding to this value of 28-day specified compressive strength is the value of modulus of rupture (MR) required by thickness design of this pavement according to said design procedure, any of these few values of modulus of rupture of concrete (MR) can be used for fatigue analysis of pavement of the certain stress ratio factor if strength safety of this pavement designed with the use of this value of modulus of rupture corresponds to preset strength safety of pavement.  
     
     
         2 . Concrete pavement of  claim 1  for highways and streets of uninterrupted traffic flow and high volumes of truck traffic of the preset strength safety level corresponding to strength safety index β equal at least to about 3, with the stress ratio factor not exceeding 0.5, fatigue analysis of pavement should be carried out with the consecutive use of the three values of modulus of rupture of concrete (MR) with the difference of 50 psi corresponding to the one value of specified compressive strength of this concrete f c ′, the least of these three is the value of modulus of rupture (MR) required by the thickness design of pavement according to the current Portland Cement Association thickness design procedure, any of these three values of modulus of rupture of concrete (MR) can be used for fatigue analysis of pavement of certain stress ratio factor if strength safety of this pavement designed with the use of this value of modulus of rupture corresponds to strength safety index β equal at least to about to 3.0.  
     
     
         3 . Concrete pavement of  claim 1  for highways and arterial streets with moderate volumes of truck traffic of the preset strength safety level corresponding to strength safety index β equal at least to about 2.5, fatigue analysis of pavement should be carried out with the consecutive use of the three values of modulus of rupture of concrete (MR) with the difference of 50 psi corresponding to the one value of specified compressive strength of this concrete f c ′, the least of these three is the value of modulus of rupture (MR) required by thickness design of pavement according to the current Portland Cement Association thickness design procedure, any of these three values of modulus of rupture of concrete (MR) can be used for fatigue analysis of pavement of certain stress ratio factor if strength safety of pavement designed with the use of this value of modulus of rupture corresponds to strength safety index β equal at least to about to 2.5.  
     
     
         4 . Concrete pavement of  claim 1  for roads, residential streets, and other streets with low volumes of truck traffic of the preset strength safety level corresponding to strength safety index β equal at least to about 2.0, fatigue analysis of pavement should be carried out with consecutive use of the three or less values of modulus of rupture of concrete (MR) with the difference of 50 psi corresponding to the one value of specified compressive strength of this concrete f c ′, the least of these three is the value of modulus of rupture (MR) required by thickness design of pavement according to current Portland Cement Association thickness design procedure, any of these three values of modulus of rupture of concrete (MR) can be used for fatigue analysis of pavement of certain stress ratio factor if strength safety of pavement designed with the use of this value of modulus of rupture corresponds to strength safety index β equal at least to about to 2.0.  
       design of pavement according to said Portland Cement Association Engineering Bulletin. Any of these three values of modulus of rupture of concrete (MR) can be used for fatigue analysis of claimed pavement of the certain stress ratio factor, if strength safety of pavement designed with the use of this value of modulus of rupture (MR) corresponds to preset strength safety level. Fatigue analysis of claimed pavements with the consecutive use of three and even two value of modulus of rupture (MR) allows obtaining the more exact estimation of fatigue strength of pavement and corresponding reduction of thickness of this pavement. Results of fatigue and erosion analyses of pavement with the trial thickness should meet requirements of said Engineering Bulletin. 
 The essence of present invention is in the more complete utilization of flexural strength of concrete, which is underestimated as a random value in the world building practice. It is applied to current thickness design procedure provided according to said Portland Cement Association Engineering Bulletin and can be applied to new thickness design procedure with the changed fatigue and/or erosion analysis of pavement.  
 Furthermore, consideration of the statistical connections between flexural and compressive concrete strength allows to choose the value of modulus of rupture (MR) required by the thickness design of this pavement according to said Portland Cement Association Engineering Bulletin in connection with the corresponding value of specified compressive strength of this concrete f c ′. It allows to provide mix design of concrete determined by this value of modulus of rupture (MR) by means of corresponding value of specified compressive strength of this concrete f c ′. Design of concrete composition by means of commonly used and well-studied compressive strength of concrete is more convenient as compared with that for flexural strength of concrete.