Investigation of Different Laboratory Aging Methods of Bituminous Mixtures

The predicted performance and service life of the pavement depend largely on the properties of bitumen used in the mixtures. The most important feature of bitumen, which has profound effect on the performance of the road is durability. The durability of bitumen is expressed as the resistance to aging. In this study, the bituminous mixture aging was performed instead of bitumen aging in order to represent the aging in the field in the best possible way. The aim of this paper is to evaluate different proposed laboratory aging methods (NCHRP 09-52, NCHRP 09-54 and RILEM) in relation with the current Standard AASHTO R30 (Standard Practice For Mixture Conditioning of Hot Mix Asphalt standard) and to make comparison with the samples performance taken from the field in terms of Indirect Tensile Strength (ITS). The level of aging has also been compared with the samples taken from recently constructed pavement surface and from the five years old pavement surface. Results depicted that, laboratory aging methods revealed the field aging properties on the unaged bitumen. Based on the results, 2 hours forced draft oven aging at 135°C is recommended as short term aging condition because, 2 hours or 4 hours short term forced draft oven aging did not yield significant variation in terms of ITS values. Additionally, 120 hours (5 days) oven aging of compacted samples at 85°C can be recommended as long term aging condition.

The Excretion of Ca, Mg, Zn and Cu Through Excreta of Laying Hens Fed Two Different Levels of Protein with and without Phytase

An 8-week experiment was conducted to study the effect of added Natuphos® 5000 phytase in corn–soybean meal-based diets on laying hens fed different levels of crude protein (CP) (14 and 17%). Two levels of phytase enzyme were used: 0 and 600 Phytase Units (FTU)/kg feed. The experiment used 144 Hisex Brown laying hens in a 2 × 2 factorial design. Four treatments and three replicates per treatment with 12 hens per replicate were used. Egg production was recorded daily while egg weight was assessed on 13th and 14th day of each two-week period to calculate total egg mass. Total excreta were collected and approximately 10% of the amount was used for analysis after drying in a forced draft oven. The results showed no significant effect of added phytase on excreta Calcium (Ca) content, but significantly lower Magnesium (Mg) content was observed with phytase (3.54, 2.48, 3.13 and 2.75 % for hens fed 14% CP no phytase, 14% CP + phytase, 17% CP no phytase, and 17% CP + phytase, respectively). Added phytase also significantly decreased Mg excretion measured as grams/kg of egg mass (21.43, 12.47, 16.76 and 14.75 g/kg egg mass for hens of respective dietary treatments. Phytase had a strong effect on Zink (Zn) levels with 438.96, 369.17, 434.38 and 374.58 mg Zn/kg dry excreta of hens. Similar results were observed with Cu. Added phytase significantly reduced the excreta content and the excretion of Cu. The results of this experiment indicate that adding 600 FTU to laying hen diets containing 14% CP decreases the excretion of Mg, Zn and Cu without any adverse effects on the egg mass produced of laying hens.

The Investigations of Fatigue Characteristics of Porous Asphalt with Organomodified Montmorillonite Modified Asphalt

In this study, organomodified montmorillonite (OMMT) modified asphalt was used in porous asphalt, and fatigue characteristics of the mixtures with or without OMMT were investigated. Special attention was paid to the beam specimens aged in a forced draft oven at 60°C for 500h. Basic fatigue information, such as stiffness, dissipated energy of the material, was obtained through four-point bending beam testing under different controlled strain. The classical fatigue life definition was used to evaluate fatigue resistance of different mixtures. The research results indicate that the OMMT mixture exhibits better fatigue and ageing resistance than the neat one. It is suggested that OMMT should be an excellent alternative for the durability of porous asphalt.

Methods of Analysis Approved by the Codex Alimentarius Commission. II. Determination of the Loss on Drying of Lactose: Collaborative Study1

A collaborative study was performed on the method recommended by the Codex Alimentarius Commission for determining loss on drying of lactose at 120°C for 16 hr. Eight samples of lactose were analyzed by 9 laboratories. Although there was no significant difference between the means of the values obtained with the convection and forced draft ovens, the precision attained by the 3 laboratories using a forced draft oven was considerably better than that attained by the laboratories using a convection oven. There is evidence that the directions for preparing samples of coarse crystals and lumpy products are inadequate

Determination of Oven Moisture in Tobacco

A comparison of mechanical convection and gravity convection oven-drying of tobacco was made on 12 tobacco samples, six with high and six with low moisture content. Data show that better interlaboratory precision was obtained by drying in a mechanical convection oven. The term “apparent moisture” is vised becavise oven drying also causes loss of volatile organic material. The magnitude of this loss is shown to be from 0.25 to 1.5%, depending on the type and treatment of the tobacco. The forced draft oven method is recommended for adoption as official, first action.

Total Solids in Oysters

Preliminary work is underway on studies of two methods for determining total solids in oysters: (a) the Radarange in conjunction with the forced draft oven, and (b) the Ohaus moisture determination balance. The results obtained by each method are compared directly with the official AOAC procedure. A 10 g sample is weighed into a Pyrex petri dish, exposed in the Radarange 4 minutes, and then placed in a forced draft oven set at 100°C for 20 minutes at full draft. The Ohaus moisture determination balance was calibrated to utilize a 9 cm diameter aluminum dish. The sample is weighed directly on the balance, and the heater is lowered over the sample long enough to dry the sample. This method is rapid (approximately 10 minutes), but only one sample may be determined at one time. Studies will be continued.

Petroleum Ether Extractables in Tobacco

Eleven collaborators participated in a study of two methods for the determination of the petroleum ether extractables in tobacco: Method I, a Soxhlet extraction of a 1 g, finely-ground tobacco sample for 3 hours; Method II, a Goldfisch extraction of a 1 g, finelyground tobacco sample for 8 hours. The petroleum ether extract was evaporated on a steam bath until the ether odor disappeared, and the residues were dried in a forced draft oven for 1 hour at 100 ± 1° C. Samples were cooled in a desiccator containing anhydrous CaCl2 before weighing the petroleum ether extractables. Good reproducibility was obtained for both methods on duplicate analyses within laboratories. However, the precision between laboratories was not as good as that within laboratories.