No abstract

The White Cement Kiln Dust (WCKD) is a byproduct material, formed in cement factory during the operation of cement production. In highway construction, the WCKD can be used in different ways such as stabilizing the subgrade of highway embankment and as mineral filler in Hot Mix Asphalt (HMA); the latter usage will give clean and healthy environment in addition to more economy. In Iraq, there are two common types of fillers, Portland cement and lime stone powder. In this research, WCKD taken from Fallujah cement plant used as mineral filler in addition to two common types. Various percentages , such as 100%WCKD, 50%WCKD + 50%Cement(C) ,100%C , 50%WCKD+50%Limestone (L), and 100% L, were used to prepare asphaltic concrete mixes. In general, five tests were used to evaluate the performance of these mixes. Standard Marshall Test procedure was applied under three different conditions, two of them at two temperatures at 60 O C and 70 O C and in the third one it was used to test samples immersed in water, at room temperature(24 O C), for four days. Indirect Tensile Strength Test (ITST) was used to evaluate conditioning and un-conditioning samples. All test results, when compared with controlled asphalt concrete sample (Sample contained 100% limestone as filler), were acceptable and within the AASHTO and Iraqi Standard Specifications of Roads & Bridges 2003. Stability values, at standard condition test, of samples containing 100% WCKD, 50%WCKD+50%C, and 50%WCKD+50%L are 11.9kN, 13.2kN, and 14.0kN respectively, while for controlled sample was 9.0kN. The Marshall stiffness values showed similar trends, for samples having 100% WCKD, 50%WCKD+50%C, and 50%WCKD+50%L giving 3.22kN/mm, 3.38kN/mm, 3.5kN/mm respectively but for controlled sample was 2.43 kN/mm. Same trends of results gained in ITST .The results showed the beneficial using of WCKD as filler that will conserve the environment and encourage the HMA producers to use this inexpensive material in their works.

The Marshall Mix design is one of the most widely used methods for designing and evaluating hot asphalt mixes globally, and the main Marshall Test focuses are stability and flow. Two standard curing methods are normally followed to elevate the temperature of testing samples; these involve immersing the samples in 60°C water or placing the samples in an oven at 60°C. These standard curing methods may not simulate the actual state of heating of asphalt pavement in the field, however. In this research, a new curing method that includes insulating the samples before immersion in hot water is thus introduced and compared with the two standard curing methods. During immersion, the water temperature is increased to 60°C and the core temperature of the insulated samples determined. Three sets of Marshall Samples were prepared and cured using the outlined methods; each set consisted of 18 specimens of 101 mm diameter and 63.5 mm height. All specimens were tested using the Marshall Test for stability, flow, and Marshall Stiffness. The set mean results showed that the oven cured samples demonstrated the highest stability values, followed by the standard water cured samples, while the insulated samples exhibited the lowest stability values. The oven cured samples also exhibited higher Marshall Stiffness Index (MSI) values than the other curing methods. However, one-way ANOVA (single factor) testing demonstrated that these differences were not statistically significant.

The proportions of aggregate directly affect the performance of HMA depending on their shape, texture, and strongly on the gradation.The determination of aggregate proportions depends strongly on the number of aggregate typesto be blended, and the limits of the desired gradation.In this research, ten samples had been taken from different text books and papers. Each one contains three types of aggregates; coarse, fine, and filler. The samples were solved individually by seven different methods; five of them by graphical method, the sixth method was solved by running MATLAB, and the last method by using Excel sheet. In this research, five graphical methods were applied, and the aim of using them is to find graphically the tentative blending values and then compare their results individually with optimum values which was found from Excel spreadsheet, and finally selecting the optimum method. For this purpose, more than 210 readings were utilized.SPSS program was run two times. In the first run, the values of person correlation (r) of method Balanced-Areas (Rothfuchs), Walace, Equal Distance, Triangular, and Asphalt Institute when correlated with optimum values were 0.973, 0.964, 0.958, 0.953, and 0.869, respectively. In second SPSS run, the values of samples No.4 and No.10 were removed because they gave zeros readings, the person correlation of Triangular, Balanced-Area, Walace, Equal Distance, and Asphalt Institute methods were 0.972, 0.970, 0.959, 0.952, and 0.869, respectively. In this research, It has been found that the Equal Distances method would be considered as an accurate, fast, and even easy method, and can be used for any number of aggregate.