Advanced Materials Research Vols. 634-638

Abstract: The self-compacting concrete is playing more and more important role in the construction industry with the advantages of greater mobility, better stability, and excellent character of filling the gap through capacity. There are different raw materials and construction conditions in each region, so, the research and development of the self-compacting concrete has a special significance according to the specific circumstances of each region. In this study, the parameters of the volume of coarse aggregate, mortar volume, the volume fraction of the sand, the mineral admixtures ash and cementatious coefficient were selected and calculated, and the C40 self-compacting green concrete was successfully configured.

Abstract: Based on the test results of compressive strength and splitting strength of three kinds of cubic specimens of pervious concrete whose side length is respectively 100mm, 150mm and 200 mm, the size effect on strength and its associated impact factors which include porosity and particle size of coarse aggregate analyzed. In the test, water cement ratio of every group of concrete mix proportion is constant. The main results are as follows: (1) Size effect on concrete of the pervious concrete is greater than that of ordinary concrete; (2) Size effect on splitting strength is greater than that on cubic compressive strength. (3) Size effect on splitting strength significantly increases with the increase of the aggregate size; (4) Weibull modulus m obtained in statistical test for compressive strength equals to 9, which should be more than twice the value of tensile strength. (5)Size effect on strength of concrete is related to its statistical discreteness, that is, the size effect is more obvious when the dispersion coefficient Cv is greater; (6)Weibull’s statistical size effect can be used to describe the size effect on strength indicators of concrete; Theoretical values of Weibull’s statistical size effect derived from the experiment agree with the test results well. (7) The abnormal trends of size effect are related to the abnormal changes of dispersion coefficient.

Abstract: Through compressive test on 18 polyurethane composite panels in 4 groups, observing their failure characteristics under compression, getting test result on compressive performance and load-deformation curve, analyzing failure reason, which will set the foundation for further experimental study and theoretical analysis.

Abstract: The efficient rapid repair for the distressed concrete pavement requires a rapid setting material that can be placed, cured, and opened to the traffic in short period. Normally, the time of the traffic open is determined by the concrete strength gain in the early hours. Meanwhile, the strength development and thermal and shrinkage properties of the concrete affect the structural and bonding performance of the repaired pavement. Type Ⅲ cement and Calcium Sulfoaluminate (CSA) cement are categorized as the rapid set cement (RSC) and are the most widely used as the cementitious material for the concrete structure rapid repair. The compressive strength of the RSC concrete cylinders with different mix proportions had been tested to obtain a strength gain guide for the rapid repair construction. Coefficient of the thermal expansion and shrinkage of the concrete were experimented. The results show that the RSC cement concretes are steady and can meet the requirement of the concrete pavement repair.

Abstract: The additive ZY, citric acid and ammonium chloride were used to modify sodium silicate and the influence of modified sodium silicate on the properties of molding sand has been investigated in this paper. The experimental results showed that the additives made the viscosity of sodium silicate increase and its surface tension reduce, the gel particle size of sodium silicate hardened by CO2 gas refine, leading to the strength at room temperature and the collapsibility of molding sand improved. The mechanism of sodium silicate modified by additives was also analyzed and it was concluded that the ZY was the best for modification of sodium silicate among experimental additives.

Abstract: One of the technologies which enables the increase of the use of fly-ash for construction purposes is the production of light cold-hardened artificial aggregate. Balling of fly-ash is possible in two ways – on the granulating plate and by means of cylindrical granulator. This article leads with the evaluation of the quality of grains produced on the granulating plate and on cylinders and, at the same time, it evaluates the suitability of the use of fly-ash from conventional and fluid burning.

Abstract: The building mortar was prepared with iron mine tailing sand substituted for natural sand, and the effect of tailing sand on the performances of mortar, such as consistency, stratification, density and strength, was investigated. The results show that it is feasible to prepare building mortar with iron mine tailing sand. The sediment percentage in tailing sand has relatively large effect on the fluidity of mortar, and the tailing sand should be washed with water before being used. When the mortar with low W/C ratio is prepared, a proper amount of water-reducing admixture should be used to adjust the stratification of mortar into the right range. The density of the mortar mixture can meet the requirement of the standard in China. The building mortars with different strength grade and different use can be prepared by adjusting the mixture proportion.

Abstract: The characteristics of the compressive strength and splitting tensile strength according to replacement ratio of the blast furnace slag were found in this study. The blast furnace slag was utilizes as the concrete mix-material and then, these results were compared with the basis presented in the international standards. In this study, cylinder made of concrete with water/binder ratio 0.34 and blast furnace slag replacement rate of 10%, 30%, 50%, and 70% were prepared to measure the compressive strength and spiting tensile strength. Test results indicate that The 28 days and 91 days compressive strength is affected by blast furnace slag replacement except specimen BS30 and the splitting tensile strength in specimen BS series is slightly larger than that of OPC except specimen BS 30.

Abstract: In order to study the impact of stone mineral composition and micro-structure on its frictional properties, 3 pavement stones used commonly were selected and researched experimentally. In the research, the frictions were measured by the specially designed facility of the State Key Laboratory of Tsinghua University and the mineral characteristics were conducted by the flake inspection, respectively. In addition, the Polishing Stone Value, abrasion value, impact value and crushing value of the 3 stones was tested. The results denote that the broader the size distributing range of compositing minerals and the greater the hardness, the larger the frictional coefficient, which indicates the mineral characteristics of pavement stones are especially essential for frictional property.

Abstract: Aiming at the deficiency of the water stability evaluation index of bituminous mixtures by immersion Marshall test in present specifications in china, the water stability of various of bituminous mixtures test pieces was analyzed by comparing freeze-thaw splitting tensile tests with immersion Marshall stability tests. There is larger difference between the evaluation results of immersion Marshall test and freeze-thaw splitting tensile test. The residual stability by immersion Marshall test is rarely inconsistent with regulatory requirements, Residual modulus is brought up to evaluate the water stability of bituminous mixtures. Residual modulus suggested to evaluate the water stability of asphalt mixtures has the similar trend with freeze-thaw splitting tensile strength ratio and the residual modulus threshold valve 0.85 is recommended.