SELECTION OF DESIGN STRENGTHS OF UNTREATED SOIL SUBGRADES AND SUBGRADES TREATED WITH CEMENT AND HYDRATED LIME
Selection of design strengths of soil subgrades and subgrades treated with cement or hydrated lime is a problem in pavement design analysis and construction. Different types of soils may exist in a highway corridor and different strengths may exist after the soils are compacted to form the pavement subgrade. The selected subgrade strength will largely affect the pavement thickness obtained from the design analysis, future pavement performance, and the overall bearing capacities of the subgrade during construction and the pavement structure after construction. In developing the proposed selection scheme, a newly developed mathematical model, based on limit equilibrium, is used. Relationships among undrained shear strength [or California bearing ratio (CBR)] and tire contact stresses are developed for factors of safety 1.0 and 1.5. The minimum subgrade strength required to sustain anticipated construction tire contact stresses during construction is determined. A criterion is proposed for determining when subgrade stabilization is needed and methods of selecting the design subgrade strength are examined. A least-cost analysis appears to be an appropriate approach as shown by analysis of a case study involving pavement failures. Two case studies show that soaked laboratory strengths appear to be fairly representative of long-term field subgrade strengths. Hence, using soaked laboratory strengths and least-cost analysis appears to be a reasonable means for selecting the design strength of subgrades for pavement analysis. To avoid failures of chemically stabilized layers, relationships among thicknesses of chemically treated layers and the CBR values of the untreated subgrade for a factor of safety of 1.5 are presented.
TEMPERATURE DISTRIBUTION WITHIN ASPHALT PAVEMENTS AND ITS RELATIONSHIP TO PAVEMENT DEFLECTION
A METHOD HAS BEEN DEVELOPED TO ESTIMATE THE TEMPERATURES AT DEPTH IN AN ASPHALTIC CONCRETE PAVEMENT UTILIZING THE MEASURED SURFACE TEMPERATURE AND THE 5-DAY AVERAGE AIR TEMPERATURE HISTORY. TEMPERATURE PREDICTION NOMOGRAPHS WERE DEVELOPED FOR EACH HOUR BETWEEN 6 A.M. AND 5 P.M. THIS TEMPERATURE PREDICTION METHOD IS INDEPENDENT OF THE SEASON OF THE YEAR. A METHOD FOR ADJUSTING BENKELMAN BEAM DEFLECTIONS FOR TEMPERATURE EFFECTS HAS BEEN DEVELOPED AND IS PRESENTED. THIS ENABLES THE DEFLECTIONS TAKEN AT ANY TEMPERATURE TO BE ADJUSTED TO A REFERENCE TEMPERATURE, THUS MAKING POSSIBLE DIRECT COMPARISONS OF DEFLECTIONS. AN ANALYSIS OF AASHO ROAD TEST DATA WAS MADE USING THE BOUSSINESQ AND BURMISTER EQUATIONS AND CHARTS. THE RESULTS INDICATE THAT THE TEMPERATURE-MODULUS OF ELASTICITY RELATIONSHIP IS CURVILINEAR, HAS THE SAME BASIC SHAPES AS THE TEMPERATURE-DEFLECTION ADJUSTMENT FACTOR CURVE. THERE APPEARS TO BE A LINEAR RELATIONSHIP BETWEEN DEFLECTIONS ADJUSTMENT FACTORS AND MODULUS OF ELASTICITY. THEREFORE, THERE SEEMS TO BE A TEMPERATURE-DEFLECTION-MODULUS OF ELASTICITY CORRELATION BETWEEN FIELD TEST DATA AND THEORY. /AUTHOR/
Clinical chemical values and variations in Rasa Aragonesa ewes and lambs
Reference values of biochemical parameters in serum of Rasa Aragonesa ewes and their physiological variations were determined. Total proteins were 53.0–80.0 g/l, glucose 2.17–5.13 mmol/l, cholesterol 0.83–2.31 mmol/l, total bilirubin 1.85–6.49 μmol/l, urea 3.15–10.39 mmol/l, GGT 36–93 U/l (37°C), ALAT 11–33 U/l (37°C) and ASAT 71–209 U/l (37°C). Ewes were divided into three groups: A, 1- and 2-year-old ewes; B, ewes 3 and 4 years old; C, older ewes. Age had significant influence (P<0.05) on ASAT only during pregnancy, with higher levels for younger ewes. Blood parameters in lambs were determined at 5–10 d of life (nursing), 25 to 30 d of life receiving their mother's milk and 80–90 g of feed; and 45 to 50 d of life, weaned, receiving only solid feed. Serum urea and ALAT tended to increase with age, whereas total protein, globulins, cholesterol and GGT decreased with age. These values are of practical importance in the diagnosis of diseases and metabolic disorders in Rasa Aragonesa ewes and lambs under field conditions.