Applied Mechanics and Materials Vols. 405-408

Abstract: High performance concrete (HPC) can be made with cement alone or any combination of cement and mineral components, such as, blast furnace slag, fly ash, silica fume, kaolin, rice husk ash, and fillers, such as limestone powder [. In this study, three mixes of high performance concrete (HPC) with same water-binder ratio and different types of mineral admixtures were prepared. he compressive strength, splitting tensile strength and modulus of elasticity values were measured in accordance with the ASTM. The influence of fly ash (FA), blast furnace slag (BS) and silica fume (SF) on mechanical properties of HPC were compared and analyzed. Their mechanical properties are measured at 7 days and 28 days. The results showed that specimen BS45+SF5 performed better than specimens BS30+FA25+SF5 and BS65+SF5 for the compressive strength, splitting tensile strength and modulus of elasticity.

Abstract: In order to understand the influence of mixture parameters on ultra-high strength self-consolidating concrete (UHS-SCC) behaviour, an experimental design was carried out in this investigation. In total, 19 SCC mixtures were prepared to determine several key responses that affect the slump flow and compressive strength of UHS-SCC. The statistical models derived from the factorial design approach can be used to quantify the effect of mixture parameters and their coupled effects on fresh and mechanical properties of SCC.

Abstract: Innovative researches on properties of sand grout with iron ore tailings (IOT) as fine aggregate were conducted. The results show that exclusive ferrous mineral in the IOT is merrihueite beside quartz in both IOT and nature sand (NS). IOT have similar thermal stability with NS. Sand grout with IOT has higher compressive strengths resulted from existence of ferrous minerals and more complex morphology of particles. However, size shrinkage of the sand grout slightly increases to 0.09% of initial testing specimen. It is feasible that IOT as fine aggregate can be used to produce sand grout.

Abstract: The synthesis process of esterification products used for the preparation of polycarboxylate superplasticizier (PCE) was systematically investigated, and the influences of water dosage, the catalyst dosage, reaction time and inhibitor dosage on the esterification rate and cement paste fluidities were determined. The results showed that the esterification rate can reach more than 95% as the water-carrying agent of 70 g, catalyst-alcohol ratio of 0.07, reaction time of 7 hours, inhibitor-acrylic acid ratio of 0.03, respectively. The obtained esterification products subsequently copolymerized with macromonomer to prepare PCE, and then the application performances were tested by adding PCE to cement pastes. From the fluidity results, the cement paste fluidity and fluidity retention capacity of PCE were better than those of commercial PCE, and this was in accordance with the high esterification rate of its esterification rate.

Abstract: This paper studied the influence on corrosion resistant performance through the rust resistance performance tests and the resistance to chloride ion penetration tests. In the tests, four test specimens were prepared: (a) blank sample without corrosion inhibitors or composite admixture; (b) mix 20% composite admixture replacing the cement; (c) mix 2% organic inhibitor replacing the cement; (d) combine 20% composite admixture and 2% organic inhibitor replacing the cement. The results showed that both of the composite admixture and the organic inhibitors had the ability to prevent steel corrosion in concrete structures and had their own advantages respectively. Mixing mineral admixture and inhibitor together had synergy effect and had more obvious anticorrosion effect, which helped the specialized production of antirust compound-admixture to ensure homogeneity of concrete.

Abstract: 4 kinds of mix proportion High performance concrete (HPC) was manufactured, whose material was produced from Inner Mongolia areas. The compressive strength and the flexural strength of HPC were obtained by the Brine Corrosion experiments. And the resistance to corrosion of HPC was analyzed by the data of Brine Corrosion experiment. Furthermore, the concrete standard curing age of HPC samples was adopted as 28d and 90d, which could impact the resistance of high performance concrete in salt brine corrosion environment. It was turned out that 4 kinds of mix proportion HPC produced a good resistance in salt brine corrosion environment. And the longer the concrete standard curing age was adopted, the better resistance in salt brine corrosion environment of HPC could produce.

Abstract: With the city's large-scale construction, there have been a shortage of river sand in some areas. So, abundant, low-cost sea sand gradually being used in construction. However, sea sand can not be directly applied to the production of building materials, such as building mortar. Sea sand must be desalted and admixtures must be added to the sea sand mortar. In this paper, using a variety of sand to make cement mortar, and comparing the performance of them. Studies have shown that, compared with the ordinary mortar, the strength and the durability of the sea sand mortar modified by colloidal crystal have improved significantly.

Abstract: The influence of mineral admixtures on workability of fresh concrete and chloride ion permeability resistance of hardened concrete for C50 self-compacting concrete was investigated by means of the Natural Immersion Test. The results showed that the chloride diffusion coefficient in fly ash concrete decreased first and then increased with increasing fly ash content in cementitious materials, when fly ash content was 30% or 40%, it got the lowest value at 28 days or 90 days, respectively. The chloride diffusion coefficient in specimens decreased with increasing the ground granulated blast furnace slag content in cementitious materials, but it changed little when the replacement was in ranges of 50% to 60%. Furthermore, for the specimens which replaced by fly ash and ground granulated blast furnace slag, the chloride diffusion coefficient decreased first and then increased with increasing the fly ash content in complex cementitious, and when fly ash content was 10% or 20%, it got the lowest value at 28 days or 90 days, respectively.

Abstract: In this paper, the current situation of nanomaterials used in concrete were introduced, mechanism of nanomaterilas was reviewed. Recent application of nanomaterilas in special concrete such as air purified concrete, eco-concrete, high tenacity concrete were present.

Abstract: This paper presents an experimental study to evaluate the effects of fly ash and nanoCaCO₃ on setting time of cement paste. The test group included the contents of fly ash was 30%, 40%, 50%, 60% and content of nanoCaCO₃ was 2.5%, 5%, 10%, 20%. Results indicate that setting time was increased with the incorporation of fly ash, shortened with the incorporation of nanoCaCO₃. The incorporation of 5% nanoCaCO₃ by mass of cementitious materials reduced initial and final setting times by 60 and 70 min, respectively. In comparison to the referenced paste with 40% fly ash. The best fly ash content appear to be 40% when nanoCaCO₃ was added.