Impermeability Of Concrete Research Articles

Study on Mechanical Properties and Impermeability of Rubber Concrete

The effects of the size and volumetric content of rubber powder on properties of concrete, including flexural strength, compressive strength and permeability, were studied in this paper. Two different particle sizes (20 meshand 60 mesh) of rubber powder were chosen to replace the sand with volume content of sand as5%, 10%, 15%, 20%, 25%, 30% respectively. The results showed that both flexural and compressive strength of concrete, especially compressive strength, decreased with the increase of rubber content. Moreover, the smaller the particle of rubber powder, the greaterer the strength of the concrete, which was not obvious as effect of rubber powder content on the strength of concrete. The impermeability of concrete increased with the increase of rubber powder content. The electric flux of concrete with 30% rubber powder reduced to about 900 C, which was only 1/5 of that with 5%. At the same content, smaller rubber particle has positiveeffects on the impermeability of concrete. Keywords: rubber concrete,rubber powder, compressive strength,flexural strength, permeability performance.

Properties and Microstructure of HPC with Lithium-Slag and Fly Ash

High performance concrete (HPC) was prepared using lithium-slag and fly ash,which are the industrial waste in Xinjiang Province,China,and its mechanical properties,crack resistance impermeability of concrete. The results showed that: lithium slag can well improve the mechanical properties of concrete, after adding fly ash, in the total dosage of 20%, the improving effect on the mechanical properties is the best; in the total dosage of 50%, its performance improvement of cracking resistance and impermeability is particularly evident, and can significantly improve the interface of concrete structures and products. At early hydration, admixture involved secondary hydration reaction generated in the interface area silicon ratio of calcium silicate hydrate and dense structure,which reduces the crystal content of loose AFt and Ca(OH)2, improving the performance of concrete mechanical and impermeability, particularly, the formation of needle AFt compensate the shrinkage of concrete and improve the performance of concrete early cracking.

Effects of Different Mineral Admixtures on the Properties of Fresh Concrete

This paper presents a review of the properties of fresh concrete including workability, heat of hydration, setting time, bleeding, and reactivity by using mineral admixtures fly ash (FA), silica fume (SF), ground granulated blast furnace slag (GGBS), metakaolin (MK), and rice husk ash (RHA). Comparison of normal and high-strength concrete in which cement has been partially supplemented by mineral admixture has been considered. It has been concluded that mineral admixtures may be categorized into two groups: chemically active mineral admixtures and microfiller mineral admixtures. Chemically active mineral admixtures decrease workability and setting time of concrete but increase the heat of hydration and reactivity. On the other hand, microfiller mineral admixtures increase workability and setting time of concrete but decrease the heat of hydration and reactivity. In general, small particle size and higher specific surface area of mineral admixture are favourable to produce highly dense and impermeable concrete; however, they cause low workability and demand more water which may be offset by adding effective superplasticizer.

Experimental Research on Impermeability of Crumb Rubber Concrete

An exhaustive study should be carried on impermeability of crumb rubber concrete in this paper. The orthogonal experimental design method was used in mixture proportion design and considered three factors and four levels respectively. Tests were carried out to investigate the behavior of different concretes with water to cement ratio, rubber content and sand to coarse aggregate ratio (Sp). The research shows that appropriate proportional fine aggregate replaced by rubber powder can improve impermeability of concrete. Rubber content played most important role among them and water to cement ratio took second place. Sp had a little effect on permeability of rubber concrete.

Experimental Study on Impermeability Performance of Chopped Basalt Fiber Reinforced Concrete

This paper studies on the influence of impermeability in basalt fiber of C50 concrete, and the result was compared with the same dosage of polypropylene fiber. Experimental test show that after incorporating basalt fiber and polypropylene fiber concrete impermeability resistance were significantly improved, the impermeability of polypropylene fiber is superior to basalt fiber.

Briefing: The effects of power washing on concrete durability

The cleaning of concrete is often undertaken on health and safety grounds, especially in a marine environment when controlling algal biofouling on stepped sea defences. Despite the fact that more local authorities are doing this, there is no published research or guidance on possible durability issues when exposing a marine concrete to regular power washing regimes. Surface analysis of concrete revetment armour at a UK study site was undertaken in order to investigate the effects of power washing over 3 years on durability. Revetment armour units were monitored from casting to placing on site and surface roughness was found to have doubled. Surface hardness and uniformity have also been measured indicating degradation. When casting revetment units upside down, vibration may encourage the larger aggregate to migrate downwards towards the exposed surface once inverted at the site. Large aggregate particles at the surface leave no surface zone, giving no erosion protection. It is at the top surface where the strongest, most impermeable and most wear-resistant concrete is needed. Continual water jet cleaning practices lead to a higher surface roughness, thereby increasing the surface area offering a bioreceptive surface for further, quicker and denser colonisation; these phenomena provoke and encourage each other.

Study on Slag Powder Concrete Preparation in Baotou Area

Using slag powder in concrete, not only can solve the piled slag powder problem in Baotou area, but also can save resources and energy and improve concrete performance, resulting in huge economic benefits. The results showed that slag powder can increase concrete mobility. With slag powder increasing, the C40 and C50 concrete 28d compressive strength increases and then decreases and each age shrinkage values are significantly reduced. When slag powder reach 50% of cement, concrete impermeability and anti-carbonation are excellent and 41.1yuan are saved every cubic meter concrete which lead to great social and economic benefits.

Experimental Research on Durability of Concrete Made by Seawater and Sea-Sand

This paper introduce a series of tests about properties of seawater and sea-sand concrete, such as impermeability, dry shrinkage, alternate wetting and drying destruction and sulfate attack. The test results show that the impermeability of seawater and sea-sand concrete and ordinary concrete is basically same, the coral sand leads to decreasing of concrete impermeability, the admixture can effectively improve the impermeability of coral sand concrete. The difference between the shrinkage rate of seawater and sea-sand concrete and the ordinary concrete is not obvious, the shrinkage rate of seawater and coral-sand concrete is larger than ordinary concrete, and the admixtures can effectively inhibit the late drying shrinkage of seawater and sea-sand concrete and seawater and coral-sand concrete. In the case of alternate wetting and drying, the pressure generated by the salt crystals would not damage seawater and sea-sand concrete. Potential sulfate attack exits in seawater and sea-sand concrete, the active admixture is able to greatly enhance its ability of resisting sulfate corrosion.

Effect of Silica Fume on Workability and Water Impermeability of Concrete

A designed experimental study has been conducted to investigate the effect of silica fume on workability and water impermeability of concrete, a large number of experiments have been carried out in this study. The results indicate that the addition of silica fume has adverse effect on the workability of concrete composite. The slump and flowability of the concretes containing silica fume is less than that of the concrete without silica fume, and a considerable decrease for the slump and flow of the concrete was observed by increasing the dosage of silica fume. Besides, the addition of silica fume can improve the water impermeability of the concrete composite evidently, and the water impermeability is becoming better and better as the silica fume content is increasing gradually.

Influence of Permeated Crystalline Waterproof Materials on Impermeability of Concrete

Influence of permeated crystalline waterproof materials on permeability and automation healing of concrete was studied by impermeability test methods for two and a few times. Microstructure of concrete was analyzed and characterized with SEM and MIP. The results showed that permeated crystalline waterproof materials had function of durable self-repairing and impermeability of concrete improved with increasing of permeated crystalline waterproof materials. It was because that reaction crystallization of active component in permeated crystalline materials and Ca(OH)2 in concrete filled interfacial of concrete and cement paste matrix. In addition, pore size distribution of concrete with permeated crystalline waterproof materials was so good that there were more content of less harmful and less content of harmful pore in concrete. Therefore, most probable pore diameter of concrete reduced and impermeability of concrete improved.

Influence of Permeated Crystalline Waterproof Materials on Impermeability of Concrete

Influence of permeated crystalline waterproof materials on permeability and automation healing of concrete was studied by impermeability test methods for two and a few times. Microstructure of concrete was analyzed and characterized with SEM and MIP. The results showed that permeated crystalline waterproof materials had function of durable self-repairing and impermeability of concrete improved with increasing of permeated crystalline waterproof materials. It was because that reaction crystallization of active component in permeated crystalline materials and Ca(OH)2 in concrete filled interfacial of concrete and cement paste matrix. In addition, pore size distribution of concrete with permeated crystalline waterproof materials was so good that there were more content of less harmful and less content of harmful pore in concrete. Therefore, most probable pore diameter of concrete reduced and impermeability of concrete improved.

Study on Impermeability Mechanism of Magnetic Water Concrete

The magnetic water can increase the strength of concrete, which can infer that the impermeability of concrete has been improved. According to the reason of permeation of concrete and on the basis of the study of magnetic water concrete by the predecessors, the effects such as hypothesis of the mechanism, action of the cement hydration, concrete workability, water ratio of the concrete, setting time and hardening process on impermeability of magnetic water concrete was studied in this issue. And the mechanism of impermeability of magnetic water concrete is also analyzed.

Experimental Study on Durability of Air-Entrained Concrete of Qingdao Bay Bridge

The permeability, frost-resistance and deicer-frost resistance of air-entrained concrete of Qingdao Bay Bridge were studied. The results show that frost-resistance and deicer-frost resistance of concrete can be enhanced by a big margin and impermeability of concrete can be also improved by appropriate air-entrainment. The frost-resistance and deicer-frost resistance of concrete samples gathered from site were inspected and they can meet the design demand for durability of concrete Qingdao Bay Bridge.

Study on Test about the Impermeability of Magnetic Water Concrete

The compactness and water impermeability of the concrete mixed with magnetized water in different degrees are studied in the thesis. According to the principle of cross-test, 21 samples with the intensity levels C20, C25 and C30 are chosen in the impermeability test. The test indicates the difference of impermeability between magnetized water concrete and ordinary water concrete at the condition of same strength to study the special law influenced by the flow speed of water and the magnetic field strength. The best magnetic field strength and the best water flow speed have been obtained among the range of test parameters.

Durability Based Indexes of Coarse Aggregate for Cement Concrete

Indexes of coarse aggregate, such as powder content, sediment percentage, maximum particle size, gradation and coarse aggregate volume ratio, are experimented and analyzed for impermeability, cracking resistance and freezing and thawing. Recommendation value based concrete durability is provided. (1) Coarse aggregate should be washed to keep surface clean during producing. (2) Clay content should not exceed 1%. (3) Coarse aggregate maximum size should not be greater than 26.5mm. 19mm and 26.5mm is the beat generally. (4) Smaller equivalent size should be used within the same gradation. (5) Coarse aggregate volume ratio is not more than 0.75 in improving anti-cracking performance for earlier concrete and in 0.70 to 0.75 in increasing impermeability of concrete.

Study on Fiber Concrete Impermeability Test and its Application in Subway Station

Standard impermeability test is used to evaluate the impermeability of concrete without bearing history. For having no test to evaluate fiber concrete with load-supporting history under service environment, a new test, splitting tensile permeability test is proposed in the paper. The proposed test method involves two parts called splitting tensile test and load holding permeability test. The splitting tensile test is used to get fiber concrete specimen with tiny crack which impermeability measured by the load holding permeability test. Based on the concept of water proof grade in underground engineering, a new method for defining fiber content is proposed to improve the impermeability of fiber concrete. The new test and method is used to define the fiber content in a subway station of shanghai metro line 7, which have well impermeability upon engineering completion. So splitting tensile impermeability test is proved to have good reliability and feasibility for evaluating fiber concrete servicing in underground engineering.

Influence of Permeability of HCSA Expansive Agent on High Volume Fly Ash Concrete

Based on the rapid determination of chloride diffusion coefficient with NEL method and pore structure analysis, the influence of HCSA expansive agent on chloride diffusion coefficient of concrete has been investigated. Besides, the effects of chloride diffusion coefficient of Water-Cement ratio on HCSA expansive concrete have been also analyzed. The results show that on the condition of 55% mixing amount of fly ash, the chloride diffusion coefficient of concrete of no HCSA is 1.96×10－8cm2/s, which is classified moderate. While the concrete mixing HCSA is about 0.62×10－8cm2/s, the permeability belongs to inferior. The effects of permeability of HCSA mixing amount on concrete is not obviously. The Water-Cement ratio affects the concrete permeability. Under the experimental conditions, the water-cement ratio of 0.4 can achieve better effect of the HCSA expansion; Furthermore, the mercury intrusion further verified that incorporating proper amount of HCSA can make the internal structure dense and improve the density and impermeability of concrete.

Impermeability of Wet-Sieving Fine Aggregate Concrete Made from Ordinary Concrete

The research is part of wet-sieving concrete technique for building thermal insulated reinforced concrete composite wall. The fine aggregate concrete is made from ordinary concrete passing sieve with square mash of 15 mm for casting surface concrete layer of the wall, the recomposed concrete is made of residual concrete stayed on sieve and ordinary concrete for casting reinforced concrete structural wall. The impermeability of fine aggregate concrete and recomposed concrete are measured by water permeation method and chloride-ion permeation method, the relative permeability and chloride-ion diffusion coefficients of concrete are determined. Based on the test, the effects of the changes of aggregate series, sand ratio and cement paste on the impermeability of concrete are analyzed.

The Effects of Concrete Strength Grade on Concrete Impermeability and Gas-Proof

In order to reveal the relation between concrete strength grade and concrete permeability, based on C20, C25, C30 and C40 concrete impermeability and gas-proof tests, the effects of concrete strength grade on concrete impermeability and gas-proof are investigated. The results show that the gas-proof and impermeability property of concrete increase when concrete strength grade are subjected to higher one.

Estudo de inibidores de corrosão em concreto armado

A corrosão é um fenômeno que afeta toda a sociedade, atribuindo-se uma grande importância sócio-econômica aos seus efeitos. Na área da engenharia, existem diversas conseqüências do processo corrosivo, como ocorre no aço de reforço das estruturas de concreto. Na intenção de oferecer segurança e durabilidade às estruturas, empresas do ramo químico e de produtos para construção civil disponibilizam no mercado diferentes formas de proteção à corrosão. Este trabalho apresenta análises de medidas de potencial realizadas em amostras de concreto armado, com diferentes relações água/cimento, produzidos com e sem inibidores de corrosão e expostos a dois ambientes com cloretos: em campo, exposto às intempéries da atmosfera marinha do litoral sul de Santa Catarina; em laboratório, a um processo cíclico de aceleração da corrosão através de imersão parcial (solução contendo cloretos) e secagem em estufa. Nas duas situações, foram mantidas as amostras por um período de 63 dias. A corrosão por cloretos em laboratório mostrou-se o sistema mais agressivo e eficiente para avaliar o potencial de corrosão. Os resultados buscaram caracterizar a eficiência dos inibidores de corrosão utilizados, que foram denominados de inibidor A, inibidor B e inibidor C e, ao fim das análises, foi possível classificá-los quanto ao desempenho em ambientes contaminados por cloretos em: Inibidor B > Inibidor C > Inibidor A. A redução da relação água/cimento (0,45) melhorou o desempenho do concreto de referência e dos três tipos de inibidores de corrosão utilizados. Evidenciou-se modificação das propriedades mecânicas dos concretos com inibidores, o que pode conduzir ao desenvolvimento de concretos mais impermeáveis e duráveis.