Advanced Materials Research Vols. 261-263

Abstract: A long term immersion test of mortar in sulfuric acid is carried out to investigate the effects of fly ash (FA) and silica fume (SF) on anti-corrosion characteristics. The mortar specimens have water to binder ratios (W/B) ranging from 0.5 to 0.7 and are divided into two series. Series one uses admixture of FA with replacement ratio from 0~0.3 and series two uses admixture of SF with replacement ratio from 0~0.1. The specimens are soaked in sulfuric acid with a pH value of 3.50 for 150 days. The portable pH meter is used to monitor the pH changing of the soak solution. The titrating sulfuric acid with concentration of 0.125mol/l is added to maintain the original pH value of the solution and then sulfuric acid consumption of specimens is recorded. A partial correlation analysis of experiment results shows that the effects of FA and SF on mortar resistance to sulfuric acid would change with the water binder ratio.

Abstract: Uniform design and non-parametric regression are introduced combined with a long time immersion test of permeable concrete soaked in sulfuric acid. The experiment contains 4 factors and 10 levels and is arranged by uniform design method. The test records the permeable coefficients and volume of acid consumption and then the datum are passed a non-parametric analysis. The results show that cement-aggregate ratio and permeable coefficient have positive, while water-cement ratio have negative, linear relationships with acid consumption.

Abstract: Test specimens were made from ordinary Portland cement (OPC) pastes containing different percentages of Acrylamide. It was measured the strength with time change. The effect of different percentages of Acrylamide on the sulfate resistance and inner pore distribution of lightweight aggregate concrete was investigated.. Test specimens were studied by X-ray diffraction, electron microprobe analysis and mercury porosimetry. The results show: The best percentage of Acrylamide was about 4%, which leads to the higher compression strength. when the content of Acrylamide was 4%, the Sulfate-Corrosion Resistance reached the climax.

Abstract: Preparation of advanced early strength agent ,the main components including organic A, organic B and calcium nitrate. Then tested advanced early strength agent performance for concrete. Though text, we find, the compressive strength and flexural strength of the specimen, use of the advanced early strength agent is greatly improved than with its much better not to use advanced early strength agent. With the passage of time, advanced early strength agent added does not make the strength of concrete worse, but better.Use SEM and XRD analysis technology text advanced early strength agent by adding performances of concrete, including the degree of cement hydration, the morphology of hydration products and the composition of mineral formation. analysis of the role of advanced early strength agents from the perspective of the mechanism. Identified advanced early strength agent impact on the cement hydration, for the further development of early strength agent to provide a theoretical basis.

Abstract: Ordinary Portland cement in corrosive environment such as saline-alkali land, sea water and chemical pollution can easily be corroded, thus cause infrastructure damage. In this paper, N-vinyl pyrrole was added into cement mortar, to improve sulphate erosive resistance of cement material. Through strength testing, quick sulfate corrosion test, XRD and SEM analysis methods in experiment, the researching results have shown that NVP can effectively improve the property of cement.

Abstract: In this article, the effects of compressive strength and carbonation depth of HCSA mixing amount on high volume fly ash concrete have been investigated. Besides, the effects of compressive strength and carbonation depth of the fly ash amount on HCSA expansive concrete have been also analyzed. The results show that proper HCSA mixing amount can improve the compressive strength and anti-carbonation resistance. On the condition of 55% mixing amount of fly ash and 6% HCSA, the compressive strength for 28 days enhanced 8MPa, the carbonation depth decreased by 0.7mm, at the age of 70, the strength increased by 12MPa and the depth reduced 1.7mm; when the mixing amount of HCSA reaches 10%, the internal structure of concrete would be destroyed; In the case of 6% HCSA amount, the compressive strength and anti-carbonation resistance decreases with the increase of fly ash mixing amount. While comparing to the concrete without HCSA, the compressive strength and anti-carbonation resistance increase obviously.

Abstract: To improve structure durability of Cao’e River Floodgate in China, durability and lifetime prediction of high-volume ground granulated blast-furnace slag (GGBS) concrete were investigated. Chloride ion permeability was analyzed with nature soaking method and RCM method. High-volume GGBS concrete had better capability to resist chloride ion penetration with lower diffusion coefficient of chloride ion than ordinary Portland concrete (OPC) had. Experiment of steel-bar corrosion in dry-wet environments proved that high-volume GGBS concrete had better performance to protect steel-bar than OPC had. In the sulfate solution, high-volume GGBS mortar bars only produced small expansion which was 40% of that of Portland cement mortar bars. The performance of frost resistance of high-volume GGBS concrete was favorable. GGBS debased the capability of carbonation resistance. Lifetime prediction illuminated high-volume GGBS concrete was beneficial to extended project lifespan. The results show that high-volume GGBS concrete can solve the facing durability problem of Cao’e River Floodgate.

Abstract: Most temperature control measurement methods are based on artificial work with anti-cracking during concrete construction. Automatic temperature control model proposed to implement computer control technology in concrete structural construction temperature control with anti-cracking to create an automatic concrete temperature control model. The model is based on temperature sensation technology, wireless transmission technology, water-pipe cooling technology, numerical simulation for the concrete structure of dynamic simulation and real-time monitoring. It can implement concrete inner temperature control to prevent temperature stress from producing cracks in concrete structure.

Abstract: Allowing for the analogy between ions diffusion and heat transfer, the numerical simulation on chloride ions diffusion in concrete can be realized following the thermal analysis module in the large general FEA software ANSYS, by reasonable equivalent of parameters. It is based on the modified model for Fick’s second diffusion law, taking the factors of temperature, humidity and time etc. into account. Hereby, the numerical simulation method is established for predicting the chloride concentration distribution with time in concrete, testified by the coastal exposure test. The test results confirm the efficiency and feasibility of the method.

Abstract: The study on the penetration of chloride ions into concrete is very important for the durability assessment and design of reinforced concrete structures. A cyclic wetting and drying test is conducted to evaluate the effects of concrete mix proportions on the penetration of chloride ions. Based on the experimental results, the variations in chloride ion content at various points in concrete with the water/cement ratio, maximum aggregate diameter, aggregate gradation, fly ash content, and anticorrosion agent content are analyzed quantitatively. It is found that the water/cement ratio, aggregate gradation, maximum aggregate diameter, and fly ash all have a larger influence on the penetration of chloride ions. These conclusions can provide theoretical evidence for the design optimization of concrete properties.