Papers by Keyword: Hydraulic Concrete

Abstract: The creation of sustainable hydraulic concrete from the use of waste materials, such as PET bottles, whose performance is better than the conventional concrete, has been a great challenge worldwide within the construction industry. This article shows a study on the application of PET fibers resulting from the recycling of post-consumer bottles, which will help increase their physical and mechanical behavior. Two concrete mixtures were made: a control mixture (M-C), with the proportions of a conventional concrete and a second mixture, adding 0.8% of PET fibers with respect to the cement mass (PR-0.8). Tests of electrical resistivity, ultrasonic pulse velocity, compressive strength, tensile strength and flexural strength were performed at the ages of 7 and 28 days. The results showed a slight improvement in the mechanical behavior of the PR-0.8 mixture, in contrast to the M-C mixture, given that a non-sudden failure occurs; while that the tests of electrical resistivity and pulse velocity indicate that the concrete produced is of good quality and durable.

Abstract: The aging of hydraulic concrete structure is a highly complicated problem. To reasonably evaluate the aging situation of a long-term operating concrete sluice, the core samples are obtained by field sampling from the sluice piers and the mercury injection experiment is carried out in this paper. The main objectives of this experimental investigation are to analyze the pore structure characteristics of the different parts in core samples and discuss the concrete aging rule of hydraulic concrete structure. The experimental results show that the aging of the hydraulic concrete has a certain relationship with the evolution of the concrete pore structure. It is feasible to use the pore structure of concrete to express the concrete aging of the hydraulic structure. The research in this paper will provide a basis for further study on the aging mechanism of the hydraulic concrete structure.

Abstract: The leaching behavior of hydraulic concrete can’t be neglected for its long-term exposure to surrounding water resulting in irreversible damage to durability, such as strength loss and porosity increase. Given that the coupling effect of leaching and freeze-thaw cycling on the durability of hydraulic concrete especially in severe cold regions is a big challenge. For the quite slow process of natural leaching, electrochemical accelerated leaching method (EALM) was proposed to investigate the damage evolution under two test schemes (scheme one is only leaching for 50 days and scheme two is first 100 rapid freeze-thaw cycles and then leaching for 50 days) designed in this work. The electrical resistivity and calcium oxide dissolution mass were measured through electrochemical impedance spectroscopy (EIS), namely two-probe method, and EDTA titration method, respectively. Based on electrical resistivity measurement, the measurable damage can be discussed during abovementioned singe and coupled tests. The results indicate that compared with single leaching test, the leaching coupled with the freeze-thaw cycling leads to over 50% electrical resistance loss.

Abstract: In recent years, a large proportion of reservoir works in Jiangxi province have emerged different kinds of new diseases, which not only hold back the benefit but also affect the safety of these projects, to some extent. Based on investigating the present situation of dams in Jiangxi province and analyzing the reasons for deterioration condition in reservoir works, the main disease for hydraulic concrete structure of ill-dangerous dams is divided into several typical types and the characteristics of the existing problems are given as well as some control measures.

Abstract: According to the vulnerable erosion ability of the ordinary hydraulic concrete, we adopt the method which adding both with superfine slag and super plasticizer to form the high performance concrete.The experiment about concrete erosion was carried out between the high performance concrete and the ordinary hydraulic concrete, the corrosion mechanism was studied respectively from the macro perspective and the micro perspective.From the experiment results we can conclude that the high performance concrete can resistance the sulfate attack which with the SO₄^2- concentration almost reached 20250 mg/L,it has better erosion resistance than the ordinary hydraulic concrete.

Abstract: A review of current worldwide researches on the durability of concrete was presented. Porosity and water content of concrete changing in wet-dry cycles were introduced, the failure mechanism of freeze-thaw and carbonation and the relation with pore structure, as well as its interaction influencing factors. Some key problems to be further studied were proposed on the basis of the research achievements of leaching.

Abstract: Be aimed at concrete surface damages of hydraulic concrete structures, a high strength repairing mortar was made in this paper. The mechanical properties and durability of repairing mortar were studied. Samples of repairing mortar preparation in laboratory and in field were tested respectively and its repair process and quality control was discussed. The results show that the repairing mortar has good mechanical property, obviously anti-abrasion property and excellent bonding performance. It can play an important role in concrete repairing in the field of hydraulic engineering. The sample property from field is a little lower than of laboratory made but still superior to design index. To achieve good repairing effect, construction technology and quality control is also the important factor.

Abstract: The crack under the action of non-load was the most significant factor to affect the concrete frost resistance durability. The Orthogonal Experimental Design (OED) Method was used in this paper to optimize the match ratio of the additive and to increase the concrete frost resistance durability by adding the PF, the FA, the WA in the concrete and replacing the cement of ordinary silicate with the compound cement. It offers the reference value to the development of the hydraulic concrete.

Abstract: Frost resistance of low antifreeze design level hydraulic concrete was studied with Climate Simulation System. Three temperature of -17°C, -20°C, -30°C were chosen as the inner low temperature of concrete specimen during freezing-thawing. The properties of mass, dynamic elastic modulus, flexural strength and compressive strength of low antifreeze design level hydraulic concrete under different low temperature were compared. And the microscopic property of low antifreeze design level hydraulic concrete was observed by environmental scanning electron microscope (ESEM).

Abstract: In this paper, the influence of the combination and fineness coordination of different cementitious materials on volume stability of hydraulic concrete were studied. With method of concrete drying shrinkage test, mortar flat test and steel ring test(ASTM C1581), the effects of cement with different fineness, different kind of mineral admixture and their combination with each different fineness levels on the concrete deformation were discussed. And the relations between the various influencing factor and concrete cracking were carried out.