Nidal Dig the test hole inside the opening of the base plate, being very careful to avoid disturbing the aaashto that will bound the hole. Calculate the dry mass of the material to the nearest 1 g 0. Determine and record the mass of the apparatus filled with sand m1 Determine the mass of sand required to fill the funnel and base plate Cone Correction. Calculate the dry in-place dry density of the material removed from the test hole as follows: The apparatus described here represents a design that has proven satisfactory.
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What is the mixing ratio in asphalt concrete? Aggregate is the granular material used in asphalt concrete mixtures which make up percent of the mixture weight and provides most of the load bearing characteristics of the mix. Therefore, the quality and physical properties of the aggregates are critical to the pavement performance.
The following is recommended: 1 Aggregates should be nonplastic. The presence of clay fines in an asphalt mix can result in problems with volume swell and adhesion of asphalt to the rock contributing to stripping problems. Specifications should limit clay lumps and friable particles to a maximum of one percent.
As surface friction increases, so does resistance of the mix to deformation. Specifications should require at least 60 percent of the plus 4 sieve material to have at least two mechanically induced fractured faces.
Since most natural sands are rounded and often contain a high percentage of undesirable materials, the amount of natural sand as a general rule should be limited to 15 to 20 percent for high volume pavements and 20 to 25 percent for medium and low volume pavements. These percentages may increase or decrease depending on quality of the natural sand and the types of traffic to which the pavement will be subjected. Asphalt concrete mixes should require a maximum dust asphalt ratio of 1.
All mixes should be plotted on these charts as part of the mix design process Attachment 1. States not using AASHTO T should be aware of the difficulty of determining the theoretical maximum density using individual ingredient specific gravities and their percentages in the mixture. These difficulties will result in inaccuracies in determining the specific gravity of the mixture.
These inaccuracies will carry through to the calculation of the densities in the compacted mat and may result in improperly compacted pavements. It is also necessary to determine the bulk dry specific gravity of the aggregate in order to determine the voids in the mineral aggregate VMA. The target value for VMA should be obtained through the proper distribution of aggregate gradation to provide adequate asphalt film thickness on each particle and accommodate the design air void system.
In addition, tolerance used in construction quality control should be such that the mix designed is actually produced in the field. How do you calculate the length of an acceleration lane? There are no specific way to calculate length of acceleration lane LA. However, from Highway Capacity Manual exhibit shows calculation to get flowrate in lane 1 and lane 2. In the equation exists LA variables.
Bending or flexural tests are the most widely used methods for assessing the fatigue resistance of asphaltic materials. The specimen is a prismatic beam, which is subjected to sinusoidal loading in the controlled strain mode.
In Europe the principal alternative is two-point bending using trapezoidal specimens, a test which was developed at LCPC in France.
What is Differential thermal contraction between asphalt matrix and the aggregate? HMA consists of several components the 2 most prevalent ones are a. The differential thermal contraction is the difference in contraction between the bitumen and the aggregate for a given temperature regime E. The difference in the change in contraction of the aggregate and the bitumen is the differential thermal contraction. Who pitched the most complete games in a single season?
Think of it this way, unquestionably the strongest structure is a solid. But now the compromises begin: Is weight a factor? Is material cost a factor? Does it need to be hollow? Once these parameters are known, then the loads must be determined. Are the loads static, dynamic, vibratory, etc. Are the loads in shear, torsional, moment, cantilever, etc.
Do we need to consider earthquake, thermal loads, or impact loads? And we must look at the desired building material s : steel has the same strength in all directions isotropic, wood, concrete, and composites are wildly non-isotropic so the direction of the loads becomes important. Take the case of a sky scraper. We must consider the shape of the occupied area as well as all the necessary load cases.
Thus we end up with a square girder structure which is not the strongest perhaps, but is adequate and meets all the other requirements. Considering bridges, for short spans the basic AASHTO concrete girder and deck is extremely durable and strong as well as cost effective. The Eiffel Tower was built for the International Exhibition of Paris in , but despite the age, it remains one of the worlds most brilliant examples of construction. Some key observations: 1.
Notice that it is open, the structural elements are exposed. This reduces wind loads routinely MPH at the top! Notice the arches combined with the "X" structural shapes. Arches are very efficient material wise, the "X" prevents buckling. Notice the width at the base. This is an amazingly stable and strong structure.
Steel actually puddled or wrought iron in this case members can be rapidly assembled. This required workers for two years. A bargain! Super lightweight: it has been said that a 1 foot high scale model would only weigh as much as a nickel!
AASHTO T 194
AASHTO T191 PDF