Applied Mechanics and Materials Vols. 477-478

Abstract: This study reports a new type compound admixture YP developed for slag cement activated by water glass. The effect of the compound admixture on properties of slag pastes, including mini slump, setting time and heat of hydration was examined. It is found that the slump of slag paste was increased from 60 mm to 120 mm by using the admixture. Furthermore, the initial and final setting times of paste with the admixture were 96 min and 132 min, while it only took 18 min and 23 min to achieve initial setting and final setting for the paste without using the admixture. In addition, the results also indicate that the initial peak was delayed for nearly 7 hours and the heat flow of hydration was reduced from 5864 μw/g to 461μw/g, when the admixture was added. It can be concluded that the new admixture is capable of imparting a significant improvement of workability of alkali-activated slag cement with a suitable setting behavior.

Abstract: Bond properties of ceramic concrete reinforced by bamboo bar were investigated based on pull-out tests. The influences of strength grade of ceramic concrete, material type, bond length, side length and notch spacing of bamboo bar on the bond strength between the bamboo bars and ceramic concrete were studied. The results show that the bond failure mode of ceramic concrete reinforced by bamboo bar without notch is majorly pulling-out failure, however, ceramic concrete reinforced by restructured bamboo (RB) bar with notch appears shear failure mode. The ultimate bond strength of ceramic concrete reinforced by RB bars is higher than that of ceramic concrete reinforced by laminated bamboo (LB) bar, which is close to that of ceramic concrete reinforced by plastic bars,but lower than that of ceramic concrete reinforced by steel bars under the same condition. When the notch spacing is 15 mm, the bond strength of ceramic concrete reinforced by RB bars is the highest. The conclusions can be usable for the the constitutive relationship of ceramic bamboo-reinforced concrete.

Abstract: In this study, a high-strength concrete containing 25% super-fine fly ash and 10% limestone powder was prepared, and its properties were investigated by comparing with those of pure cement concrete. The results show that the concrete containing super-fine fly ash and limestone powder can get a larger initial slump and a smaller slump loss than the pure cement concrete with the same super plasticizer content. In the case of almost the same 28 days' compressive strength, the concrete containing super-fine fly ash and limestone powder exhibits a lower adiabatic temperature rise, a lower early strength, a higher late strength, a lower permeability, and a larger carbonation depth than the pure cement concrete.

Abstract: To explore retarders on performance of ultra-early strength grouting material, Retarder, which are commonly used in the market after a preliminary screening, are further tested and analyzed for initial fluidity, setting time and mechanical strength properties of super early strength grouting material. The results show that: When borax content is 0.4%, the initial fluidity, final setting time, workability, mechanical strength are the best.

Abstract: In the trial, the author explores sodium nitrite, triethanolamine and sodium on fluidity initial and final setting time, flexural strength and compressive strength and other properties, of early strength reinforcement material. The results showed that, when sodium nitrite content is 0.2%, triethanolamine content is 0.05%, the dosage of sodium sulfate is 0.8%, final setting time for 58min, the initial flow greater than 320[mm], 30min flow greater than 280[mm], 2h compressive strength of 30[MPa], 1d bending greater than 10[MPa], 28d compressive strength greater than 90[MPa], on the early strength reinforcement, meet construction requirements.

Abstract: The properties of the concrete with super-fine steel slag were compared with those of the pure cement concrete. Results show that the concrete with 20% super-fine steel slag has similar compressive strength, elastic modulus, and permeability with the pure cement concrete at the age of 28 and 90 days. The addition of super-fine steel slag tends to decrease the initial slump of concrete, but it has a good ability of prevention of slump loss. The concrete with super-fine steel slag has similar anti-carbonation capacity with the pure cement concrete. The concrete with 30% super-fine steel slag has lower compressive strength, lower elastic modulus, and higher permeability than the pure cement concrete.

Abstract: Hot ductility of HRB500E vanadium-containing steel rebar was study with thermal simulation test and the secondary cooling model was established based on the relationship between the cooling water and the casting speed. The solidification cooling curves and the temperature fields of HRB500E were simulated with the PROCAST software. The result of the hot ductility and the pin shooting experiment shows that the casting straightening temperature should be above 902 °C and the secondary cooling model was feasible and accurate. Finally the high-quality billet of HRB500E was obtained.

Abstract: For lightweight aggregate concrete, fiber materials can reinforce its toughness and strength better and improve its segregation degree greatly. Specifically, as the experiment indicates, the fluidity of concrete mix decreases slightly after 0.5% basalt fiber and 0.5% PVA fiber are incorporated into the concrete with FA ceramsite as lightweight aggregate. However, its segregation degree reduces about 50%. And its 28d cubic compressive strength increases 0.7% and 28d splitting tensile strength increases 12.7%. Therefore, this effect is better than that of adding only one kind of fiber.

Abstract: After rubber particles are incorporated into ordinary cement concrete, properties of concrete are changed. Specifically, by comparison with concrete without rubber particles, it reduces that the collapsed slump, apparent density, cubic compressive strength, splitting tensile strength and elastic modulus of rubber particles modified concrete. And when less than 50% of sand is replaced by rubber particles, rubber modified concrete can meet requirements of workability. Besides, its self-weight decreases, which is favorable for its structure to resist earthquakes.

Abstract: The present domestic modifiers are mainly by-products of petroleum --- costing high and non-renewable, which lead to the difficulty in their wide use. This paper explores the mechanisms of purified diatomite, enhancing the stability of asphalt mixture under high temperature, low temperature or with water. At the same time, the paper makes analysis on the economy of project application, providing theoretical and economical references for spreading purified diatomite as a new modifier.