Specifications for bituminous road mix surface dense-graded aggregate type, subclass B-1 : effective June 1, 1937 ...

At head of title: ... U.S. Bureau of Public Roads' class B.

Specifications for bituminous surface dense-graded aggregate type, subclass B-2 (Machine mix) : effective July 15, 1937.

Reproduced from typewritten copy.

Specifications for bituminous surface dense-graded aggregate type, subclass B-3 (Plant mix) : effective May 15, 1939.

Mode of access: Internet.

Specifications for bituminous road-mix surface dense-graded aggregate type, subclass C-1 : effective June 1, 1945.

Reproduced from typewritten copy.

Specifications for bituminous surface dense-graded aggregate type, subclass C-6 (Machine mix) : effective September 1, 1937.

At head of title: ... U.S. Bureau of Public Roads' class C.

Specifications for bituminous concrete binder and surface courses, coarse dense-graded aggregate type, subclass I-1, nonproprietary, hot-mix : effective April 1, 1945.

Reproduced from typewritten copy.

Specifications for bituminous concrete binder and surface courses, fine dense-graded aggregate type : subclass I-11, nonproprietary hot-mix : effective March 15, 1945.

Reproduced from typewritten copy.

Specifications for bituminous concrete binder and surface courses, fine dense-graded aggregate type : subclass I-11, nonproprietary, hot-mix : effective February 1, 1949.

Mode of access: Internet.

Specifications for bituminous surface dense-graded aggregate type, subclass B-2 (Machine mix) : effective May 15, 1939 ...

Cover-title.

A Laboratory Investigation into the Effects of the Aggregated Related Facts of Critical VMA in Asphalt Paving Mixtures, June 2000

This report summarizes research conducted at Iowa State University on behalf of the Iowa Department of Transportation, focusing on the volumetric state of hot-mix asphalt (HMA) mixtures as they transition from stable to unstable configurations. This has raditionally been addressed during mix design by meeting a minimum voids in the mineral aggregate (VMA) requirement, based solely upon the nominal maximum aggregate size without regard to other significant aggregate-related properties. The goal was to expand the current specification to include additional aggregate properties, e.g., fineness modulus, percent crushed fine and coarse aggregate, and their interactions. The work was accomplished in three phases: a literature review, extensive laboratory testing, and statistical analysis of test results. The literature review focused on the history and development of the current specification, laboratory methods of identifying critical mixtures, and the effects of other aggregate-related factors on critical mixtures. The laboratory testing involved three maximum aggregate sizes (19.0, 12.5, and 9.5 millimeters), three gradations (coarse, fine, and dense), and combinations of natural and manufactured coarse and fine aggregates. Specimens were compacted using the Superpave Gyratory Compactor (SGC), conventionally tested for bulk and maximum theoretical specific gravities and physically tested using the Nottingham Asphalt Tester (NAT) under a repeated load confined configuration to identify the transition state from sound to unsound. The statistical analysis involved using ANOVA and linear regression to examine the effects of identified aggregate factors on critical state transitions in asphalt paving mixtures and to develop predictive equations. The results clearly demonstrate that the volumetric conditions of an HMA mixture at the stable unstable threshold are influenced by a composite measure of the maximum aggregate size and gradation and by aggregate shape and texture. The currently defined VMA criterion, while significant, is seen to be insufficient by itself to correctly differentiate sound from unsound mixtures. Under current specifications, many otherwise sound mixtures are subject to rejection solely on the basis of failing to meet the VMA requirement. Based on the laboratory data and statistical analysis, a new paradigm to volumetric mix design is proposed that explicitly accounts for aggregate factors (gradation, shape, and texture).

Plasma-enhanced chemical vapor deposition of boron nitride thin films from B2H6-H2-NH3 and B2H6-N2 gas mixtures

Highly transparent and stoichiometric boron nitride (BN) films were deposited on both electrodes (anode and cathode) of a radio-frequency parallel-plate plasma reactor by the glow discharge decomposition of two gas mixtures: B2H6-H2-NH3 and B2H6-N2. The chemical, optical, and structural properties of the films, as well as their stability under long exposition to humid atmosphere, were analyzed by x-ray photoelectron, infrared, and Raman spectroscopies; scanning and transmission electron microscopies; and optical transmittance spectrophotometry. It was found that the BN films grown on the anode using the B2H6-H2-NH3 mixture were smooth, dense, adhered well to substrates, and had a textured hexagonal structure with the basal planes perpendicular to the film surface. These films were chemically stable to moisture, even after an exposition period of two years. In contrast, the films grown on the anode from the B2H6-N2 mixture showed tensile stress failure and were very unstable in the presence of moisture. However, the films grown on the cathode from B2H6-H2-NH3 gases suffered from compressive stress failure on exposure to air; whereas with B2H6-N2 gases, adherent and stable cathodic BN films were obtained with the same crystallographic texture as anodic films prepared from the B2H6-H2-NH3 mixture. These results are discussed in terms of the origin of film stress, the effects of ion bombardment on the growing films, and the surface chemical effects of hydrogen atoms present in the gas discharge.

Bituminous Mixes Prepared with Ungraded Local Aggregates, Iowa Highway Research Board Bulletin No. 19, 1960

Joint Publications from Iowa Engineering Experiment Station - Bulletin No. 190 and Iowa Highway Research Board - Bulletin No. 19. This bulletin is a report on the development of bituminous paving mixtures containing various local materials and asphaltic binders. The laboratory investigations described in this bulletin were performed as part of Iowa Highway Research Board project HR-20, "Treating Loess, Fine Sands, and Limestone Dusts With Liquid Binders." This project was awarded to the Iowa Engineering Experiment Station of Iowa State University in 1952, and continued to June, 1958.

Preliminary Floatation Tests on the Beneficiation of a Low-Grade Montana Bituminous Coal.

Coal is an aggregation of vegetal matter with varying small amounts of mineral and animal matter which have been so changed by the processes of sedimentation, decay and metamorphism that it has become a dense, dark, combustible substance. It occurs in beds varying in thickness from one foot or less to over 300 feet. The horizontal extent of a bed is sometimes continuous over an area as large as the State of Montana.

Using Sewage-Sludge Ash as Filler in Bituminous Mixes

In this study, the behavior of bituminous mixes made with sewage sludge ash (SSA) as mineral filler was investigated. The behavior of these mixes was evaluated with the Cantabro, indirect tensile strength, water sensitivity, permanent deformation, and resilient modulus tests. The results show that SSA waste may be used in bituminous mixes at approximately 2–3% weight percent, maintaining adequate levels of cohesion and adhesion in the mixtures, which is comparable to mixtures made with active fillers such as hydrated lime and cement. Moreover, its use does not increase permanent deformations. However, the resilient modulus test gave slightly lower results for mixes made with SSA than for mixtures made with other fillers. It may be concluded that SSA waste may be used as a filler for bituminous mixes with better results than for mixes made with limestone fillers and with similar results for mixes made with other fillers such as hydrated lime and cement.

Investigation on performance characteristics of dense graded hot mix asphalt with RAP and Crumb Rubber

The use of recycled materials in asphalt mixtures such as reclaimed asphalt pavements (RAP) have become widely accepted as a replacement for virgin asphalt binder or virgin aggregates. In this study, the RAP content was 30%, and CR additives were blended with the soft unmodified binder by using dry processes. The objective of this study was to investigate and evaluate the engineering properties of dry method application of crumb rubber influences on reclaimed asphalt pavement (RAP) mixtures. To evaluate the effect of rubber-bitumen interaction on the mixture’s mechanical properties, a laboratory investigation has been conducted on a range of dense graded and 30% RAP by dry process crumb rubber modified (CRM) asphalt mixtures containing 0% (control), 1% crumb rubber by the total aggregate mass. The experimental program in this research include the binder extraction for estimating the amount of aged binder in the both fine and coarse RAP material. Before extracting the binder the RAP sieve analysis, have been done to provide the Black grading curve. In continue after the binder extraction the material sieved again to providing the white curve. The comparison of Black and White curve indicated that there is a remarkable difference between the aggregate grading even for the fine RAP. The experimental program was continued by fabricating 12 specimens in different 4 types of mixtures. For the first group no RAP, no rejuvenator and no crumb rubber were used. For the second group 30% of virgin aggregates substituted by RAP material and the third group was similar to the second group just with 0.01% rejuvenator. the forth group was the group, which in that the specimens contain RAP, rejuvenator and crumb rubber. Finally the specimens were tested for Indirect tensile strength. The results indicated that the addition of crumb rubber increased the optimum amount of binder in the mixture with 30% RAP.