Issue 41

Y. Yang et alii, Frattura ed Integrità Strutturale, 41 (2017) 339-349; DOI: 10.3221/IGF-ESIS.41.45 341 test at each dose. The final test results are: the dosage of cement added into the cement stabilized macadam is 4.5%, the maximum dry density is 2.35g/cm 3 and the optimum water content is 4.5%. Test Results specification Fineness (Sieve size 80μm) 1.8 ≤10% Initial setting time (min) 302 ≥180 Final setting time (min) 364 ≥360 Stability (mm) 3 ≤5 3 day flexural strength of cement mortar (MPa) 4.7 ≥2.5 3 day compressive strength of cement mortar (MPa) 19.9 ≥10 Table 1 : The characterization of Xing’an Hailuo ordinary Portland cement PC32.5. Test Coarse aggregate specification Content of needle and plate particle 11.7% ≤20% Crushing value 19.8% ≤30% Liquid limit& Plasticity index of Particles less than 0.6mm Liquid limit≤28% 26.5% Plasticity index≤9 6.2 Table 2 : The characterization of the limestone aggregate. Mesh size (mm) Pass rate (%) 26.5 100 19 92.5 16 85.5 13.2 77.0 9.5 62.7 4.75 34.4 2.36 21.2 1.18 17.0 0.6 11.5 0.3 8.2 0.15 5.1 0.075 3.6 Table 3 : Synthetic Aggregate Gradation of Cement Stabilized Macadam. Based on the above data, according to the requirements in the test regulations [14], we make specimens for flexural strength and flexural modulus, whose size is 100mm×100mm×400mm. We use the static molding method in the specimen molding. After that, specimens are put in a standard preservation room (temperature: 20°C±2°C; humidity ≥ 95%) for 90 days of preservation. Description of the tensile, compression and flexural test method We use MTS (Material Test System) for modulus testing. The test principle is shown in Fig. 1, 2 and 3. The mid-span deflection is measured using a micrometer placed on the upper surface of the specimen, which is used to calculate the flexural modulus of the specimen; the compressive strain of the mid-span upper surface and the tensile strain of the lower surface are measured by the strain gauges attached to the surface, respectively, which are used to calculate the compression modulus and tensile modulus of the specimen.