Low Permeability Concrete Research Articles

Study into the freeze-thaw/ frost-salt resistance of high-strength B60–B100 concrete

Introduction. The development of the Arctic Region and oil and gas fields in the North Atlantic Ocean leads to an increase in the production of high-strength concrete structures. Thus, it is becoming increasingly vital to make such low-permeability concretes more freeze-thaw resistant.Aim. To conduct experimental studies for obtaining reliable data required to develop a standardized approach to the normalization of freeze-thaw / frost-salt resistance parameters characterizing high-strength concretes.Materials and methods. The study was performed using concretes of eight compositions (B60–B100 compressive strength grades). The freeze-thaw/frost-salt resistance of high-strength concretes was determined using the third rapid method involving the saturation, freezing, and thawing of samples in a 5 % sodium chloride solution, as well as assessment of freeze-thaw resistance in terms of strength, mass variation, and the dynamic modulus of elasticity. A variety of methods for increasing the water saturation of highstrength concrete were examined in order to expedite the testing process of high-strength concrete for freeze-thaw resistance.Results. The studies into the freeze-thaw/frost-salt resistance of high-strength B60-B100 concretes revealed their high freeze-thaw resistance. Following 37 freeze-thaw cycles, the lower confidence limit for the strength of test samples was higher than that of control samples multiplied by a coefficient of 0.9. The frost-resistance grade of these concretes is above F2 300. No critical decrease in the dynamic modulus of elasticity is observed, which indicates a significant freeze-thaw/frost-salt resistance of all tested highstrength concrete compositions.Conclusions. The freeze-thaw resistance studies of high-strength concretes carried out at NIIZHB named after A.A. Gvozdev yielded experimental data required to subsequently develop a standardized approach to the normalization of freeze-thaw/frost-salt resistance parameters characterizing high-strength concretes.

Effect of Reinforcing Steel Fiber on Permeability of High Strength and Ultra Low Permeability Concrete

Effect of Reinforcing Steel Fiber on Permeability of High Strength and Ultra Low Permeability Concrete

Precise Permeability Measurement for High Strength and Ultra Low Permeability Concrete under Controlled Temperature

Precise Permeability Measurement for High Strength and Ultra Low Permeability Concrete under Controlled Temperature

Precise Permeability Measurement for High Strength and Ultra Low Permeability Concrete under Controlled Temperature

Precise Permeability Measurement for High Strength and Ultra Low Permeability Concrete under Controlled Temperature

COMPARATIVE ANALYSIS OF METHODS FOR DETERMINING THE EFFECTIVE CO2 DIFFUSION COEFFICIENT IN FINE-GRAINED CONCRETE OF DIFFERENT DENSITIES

Direct and indirect methods for determining the effective diffusion coefficient of CO2 in concrete are considered. The features of the diffusion process in a capillary-porous body are described. Based on the test results of samples of fine-grained concrete with different densities, a comparative analysis of the coefficients obtained by the main methods was carried out. The criteria for comparison were the dependence of the water-cement ratio on diffusion, as well as the rate of carbonization on time. The presence of significant deviations in the low permeability concretes of the coefficients obtained by the membrane methods of 72 % and the electrical conductivity of concrete saturated with electrolyte 85 % in the low permeability concrete from the values obtained by the carbonization method was established.

Low Permeability Concrete for Buildings Located in Marine Atmosphere Zone using Clay Brick Powder

The concrete is not one hundred percent impermeable since the water that remains inside it causes its corrosion, in the case of reinforced concrete, exposed in an area of marine atmosphere, the sea salt mostly present in large particles of the marine spray, produce the reduction of the alkalinity of the concrete causing a rapid corrosion of the steel. There are buildings built in this marine area that have been designed without durability criteria, in which the use of pozzolanic materials is considered, for example, to fill the pores of the cement matrix and thus guarantee its impermeability. In the present study, the effect of clay brick powder (PLA) as a replacement for cement in concrete manufacturing is addressed, evaluating different characteristics of its components. The results indicate that pozzolanic activity and compressive strength increase, slump, voids content and the coefficient of permeability to water decreases.

High Performance Self-Compacting Concrete with Electric Arc Furnace Slag Aggregate and Cupola Slag Powder

The development of self-compacting concretes with electric arc furnace slags is a novelty in the field of materials and the production of high-performance concretes with these characteristics is a further achievement. To obtain these high-strength, low-permeability concretes, steel slag aggregates and cupola slag powder are used. To prove the effectiveness of these concretes, they are compared with control concretes that use diabase aggregates, fly ash, and limestone supplementary cementitious materials (SCMs, also called fillers) and intermediate mix proportions. The high density SCMs give the fresh concrete self-compacting thixotropy using high-density aggregates with no segregation. Moreover, the temporal evolution of the mechanical properties of mortars and concretes shows pozzolanic reactions for the cupola slag. The fulfillment of the demands in terms of stability, flowability, and mechanical properties required for this type of concrete, and the savings of natural resources derived from the valorization of waste, make these sustainable concretes a viable option for countless applications in civil engineering.

The Effect of Green Inhibitor on strength and water permeability of concrete

Reinforce concrete durability treated with green inhibitor were experimentally studied. The permeability and strength of a concrete plays a critical and significant role in controlling the properties of concrete, and serviceability of reinforced concrete. It is a usual practice to assess the water permeability characteristics when assessing the durability characteristics. In the present investigation, initial surface absorption test was used to determine the water permeability of concrete of w/c (0.45) to simulate compacted and porous concrete. Bambusa arundinacea green inhibitor absorptions for 10min, 30min, 1h and 2h, is generally less than 0.25, 0.17, 0.1 and 0.07 ml/m2.s respectively, that is, the set ISAT standard for low permeability concrete. This might be possible as a result of residual alkalinity of potassium hydroxide (KOH) present in the concrete evident from inductively coupled plasma-mass spectrometry (ICPMS) result. KOH is adequate for passivation and reduction of permeability, which serve as a chemical water barriers or hydrophobic agents.Keywords: Concrete; Calcium-Silicate-Hydrate (C-S-H); Compressive strength; Permeability; Portlandite

The Effect of Green Inhibitor on strength and water permeability of concrete

Reinforce concrete durability treated with green inhibitor were experimentally studied. The permeability and strength of a concrete plays a critical and significant role in controlling the properties of concrete, and serviceability of reinforced concrete. It is a usual practice to assess the water permeability characteristics when assessing the durability characteristics. In the present investigation, initial surface absorption test was used to determine the water permeability of concrete of w/c (0.45) to simulate compacted and porous concrete. Bambusa arundinacea green inhibitor absorptions for 10min, 30min, 1h and 2h, is generally less than 0.25, 0.17, 0.1 and 0.07 ml/m2.s respectively, that is, the set ISAT standard for low permeability concrete. This might be possible as a result of residual alkalinity of potassium hydroxide (KOH) present in the concrete evident from inductively coupled plasma-mass spectrometry (ICPMS) result. KOH is adequate for passivation and reduction of permeability, which serve as a chemical water barriers or hydrophobic agents. Keywords : Concrete; Calcium-Silicate-Hydrate (C-S-H); Compressive strength; Permeability; Portlandite

Green Bambusa Arundinacea leaves extract as a sustainable corrosion inhibitor in steel reinforced concrete

The experimental studies carried out on water permeability resistance and microstructure of reinforced concrete treated with Bambusa arundinacea as green corrosion inhibitor, are reported in this article. The effectiveness of Bambusa arundinacea as green corrosion inhibitor was compared with that of calcium nitrite and ethanolamine inhibitors. Concrete mix was designed for a compressive strength of 30 MPa with a 0.45 water-to-cement ratio (W/C) which was chloride contaminated. Inhibitors addition was 2% by weight of cement. The specimens were subjected to various tests, namely; compressive strength test, durability (permeability using initial surface absorption test (ISAT) and field emission scanning electron microscopy (FESEM)) for 360 days exposure. Water absorption values of steel reinforced concrete in the presence of Bambusa arundinacea inhibitor were generally less than 0.25, 0.17, 0.1 and 0.07 mL/m2 s after 10 min, 30 min, 1 h and 2 h, i.e., as required by ISAT standard for low permeability concrete. This might possibly be due to the presence of residual alkalinity of potassium hydroxide (KOH) in the concrete. KOH is adequate for passivation and reduction of permeability, which serves as a chemical water barrier or hydrophobic agent that stabilizes calcium silicate hydrates.

Evaluation of Sealing of Macro-Fracture in High Strength and Ultra Low Permeability Concrete in Water Using Micro-Focus X-ray CT

Evaluation of Sealing of Macro-Fracture in High Strength and Ultra Low Permeability Concrete in Water Using Micro-Focus X-ray CT

Properties and Performance of Concrete Made with Recycled Low-Quality Crushed Brick

During the past decades, in most industrialized countries, a large number of old buildings have been demolished and millions of tons of construction debris have been produced. Demolition wastes around cities have become a serious environmental issue and a threat to underground water quality and result in unpleasant views. Today, less than 5% of clay bricks taken from demolition sites are being separated and recycled, whereas the proportion of concrete waste being recycled is above 90%. This low rate of brick recycling is due to a lack of understanding about the performance of crushed brick material as aggregate in concrete or road base. In the case of concrete, the high water absorption of crushed brick and its relatively low compression strength in comparison with natural aggregate makes it difficult to meet traditional concrete specifications. The present research is an effort to investigate the properties of crushed clay bricks taken from demolition sites and experimentally evaluate the strength and durability characteristics of the concrete prepared using the crushed clay bricks. The experimental data reveal that, in spite of high porosity and absorption of recycled crushed brick, using this material as aggregate results in a semilightweight, durable, and low-permeability concrete.

Microbial Participation in the Formation of Calcium Silicate Hydrated (CSH) from Bacillus subtilis

Primary hydration of cement induces the formation of calcium silicate hydrated (C-S-H) gel and the latter contributes towards the strength development of concrete. The secondary hydration derived from pozzolanic materials such as silica fume is dependent upon the formation of C-S-H gel of the primary cement hydration reaction. The additional formation of C-S-H gel as a result of second hydration process, densities the cement microstructures producing low permeability concrete. However, the silica fume is considered expensive material and its availability is limited. Therefore, it is essential to utilise living elements as an alternative agent to form the C-S-H gel. In the present study, the untreated Bacillus Subtilisand chemically modified Bacillus subtilis(CMBS) were prepared. CMBS was prepared by reacting with ethylenediamine to modify its cell wall to become electropositive facilitating the binding of the silicate during the incubation process. The cell was then incubated in the Si solution (Na2SiO3.5H2O) for 10 days which enables the SiO32- (silica ion) from the solution to be bonded with the cell wall. The C-S-H gel is expected to be formed from the bonded silica of the cell wall when mixed with saturated calcium hydroxide solution which the latter simulates the concrete environment. The presence of C-S-H gel was then substantiated using X-Ray Diffraction (XRD) analysis. In another series of study, the difference concentration of Bacillus subtiliswere incorporated into the grade 30 concrete specimens and the compressive strength up to 60 days of age were tested. The results showed that the silicate was adsorbed by Bacillus subtilisand there is no difference in the amount of Si adsorbed between untreated Bacillus subtilisand CMBS. The incorporation of Bacillus subtilisinto the concrete enhanced the compressive strength and the concentration of 106 cell/ml was found tSo be the optimum concentration.

Extending internal curing to concrete mixtures with W/C higher than 0.42

Internal curing (IC) is an effective method for improving performance of low W/C – low permeability concretes because they require additional water to hydrate the cementitious materials. Conventional concretes, on the other hand, contain enough water to hydrate the cementitious materials, but are frequently not properly cured, allowing drying and compromising strength gain and durability. The aim of this investigation is to assess the effect of IC as a complement to traditional curing in relatively high W/C concretes (W/C above 0.42) under drying conditions. Degree of hydration, compressive strength, and permeability were measured in concretes with IC and without IC. Results show that even under drying conditions, mixtures with IC exhibit 16% higher hydration, 19% higher compressive strength, and 30% lower permeability than their counterparts with no IC. This suggests that IC can be very useful for improving performance in concrete mixtures with relatively high W/C under poor curing conditions.

Subcritical crack growth and long-term strength in rock and cementitious material

High-strength and ultra low-permeability concrete (HSULPC) is a strong candidate for a radioactive waste package containing transuranic radionuclides (TRU waste) for geological disposal. Knowledge of the time-dependent fracturing of HSULPC and surrounding rock mass is essential to assess the long-term stability of such underground repositories. We have measured crack velocity in andesite and HSULPC both in air and water to examine subcritical crack growth by the Double-Torsion method. In air, the crack velocity in andesite increased when the temperature and relative humidity increased. On the other hand, the temperature and relative humidity had little effect on the crack velocity in HSULPC in air. In water, the crack velocity increased when the temperature was higher for both andesite and HSULPC. Using these experimental results, the long-term strength was estimated. It was shown that the long-term strength of HSULPC was higher than that of andesite. In air, the long-term strength for andesite was affected by the temperature and relative humidity. The long-term strength for andesite decreased when the temperature or relative humidity increased. For HSULPC, the change of the long-term strength with varying temperature or relative humidity was smaller than andesite in air. In water, the long-term strength for both materials decreased with increasing the temperature. Comparing the long-term strength of andesite and HSULPC at the same environmental conditions, it was recognized that the decrease of the long-term strength of HSULPC is smaller than that of andesite. The long-term strength in water was smaller than that in air for both materials.

Concrete and Steel Type Influence on Probabilistic Corrosion Service Life

In the United States, a major portion of high bridge rehabilitation costs remains bridge deck deterioration due to chloride-induced corrosion. Fickian diffusion process modeling was performed on chloride ingress through cover concrete. The service life analyses tool used a validated chloride-induced corrosion service life model incorporating the probabilistic nature of chloride corrosion initiation concentrations, surface chloride concentrations, steel cover depths, and chloride ingress. For the survey of 26 bridge decks, model input values were determined and supplemented by literature. Virginia, Pennsylvania and New York bridge service lives were modeled as increasing chloride exposures. There was investigation of how time-to-rehabilitation was influenced by stainless, microcomposite-chromium, and galvanized steel; alternate steel types; and low-permeability concrete.

Subcritical Crack Growth and Long-Term Strength in Rock and High-Strength and Ultra Low-Permeability Concrete

High-strength and ultra low-permeability concrete (HSULPC) is a strong candidate for a radioactive waste package containing transuranic radionuclides (TRU waste) for geological disposal. The information and knowledge of the time-dependent fracturing of HSULPC and surrounding rock mass are essential to assess the long-term stability of such underground repositories. Here we measured crack velocity in andesite and HSULPC both in air and water to examine slow crack growth (subcritical crack growth) by Double-Torsion method. In air, the crack velocity in andesite increased when the temperature increased. On the other hand, the temperature had little effect on the crack velocity in HSULPC in air. In water, the crack velocity increased when the temperature was higher for both andesite and HSULPC. By using the experimental results of subcritical crack growth, the long-term strength was estimated based on the model of a single crack subjected to tension in an infinite plate. It was shown that the long-term strength of HSULPC was higher than that of andesite. When the temperature increased, the long-term strength of andesite both in air and water and that of HSULPC in water decreased. The long-term strength in water was smaller than that in air for both materials. It is concluded that water remarkably affects subcritical crack growth and the long-term strength in these materials.

Subcritical Crack Growth and Long-Term Strength in Rock and High-Strength and Ultra Low-Permeability Concrete (Vol.58, No.6)

訂正項目：本文, pp.530, コラム：右

Precision of the Nordic test methods for measuring the chloride diffusion/migration coefficients of concrete

This paper presents the results of the round-robin test carried out in the Nordic countries to evaluate the repeatability and reproducibility of three Nordic test methods for measuring the chloride diffusion coefficient of concrete. The three methods were: NT BUILD 443, NT BUILD 355 and the CTH Rapid Test. A total of nine laboratories from Denmark, Sweden, Norway and Iceland participated in the test. Concrete specimens with three types of binder and two water-cement ratios were used in the test, and the test results were evaluated in accordance with international standard ISO 5725-94 for the determination of repeatability and reproducibility, in spite of small numbers of trials and laboratories. The results show that, among the three methods tested in this project, the CTH Rapid Test in general gives the best precision in the determination of chloride diffusion coefficient for Portland cement or silica fume concrete. The NT BUILD 443 method also gives satisfactory precision. The NT BUILD 355 method gives satisfactory precision for permeable concrete, but shows poor reproducibility for dense or low-permeability concrete.

Sulphate resistance of type V cements with limestone filler and natural pozzolana

Sulphate performance of concrete depends primarily on permeability. Under severe conditions of sulphate exposure, low-permeability concrete is prescribed and it must also be made with high sulphate resisting cement. For portland cement, the sulphate resistance depends on the C 3A content and the amount of CH produced at early stages of hydration. Some parameters that modify the quantity of early CH in the hardened cement paste are investigated in this paper. Two type V cements with quite different C 3S content and blended cements containing natural pozzolana or limestone filler were used. Expansion, flexural and compressive strength of mortar, immersed until 1 yr in sodium sulphate solution, with pH-controlled are presented. Results show that the sulphate performance of portland cement with high C 3S content is very poor compared with low C 3S portland cement. Addition of natural pozzolana provides the maximum sulphate resistance while the addition of 20% limestone filler declining sulphate performance of low C 3A cements. This behaviour can be attributed to the reaction between sulphate ions with CH into the paste that produces an alteration of the predominant mechanism of sulphate attack.