Durability Of High Performance Concrete Research Articles

Durability evaluations of bridge deck high-performance concrete

Although several information are available on various aspects of durability of high-performance concrete (HPC), no systematic information is available on durability of HPC used for bridge decks. In this study, 12 HPC mixtures were prepared with different combinations of fly ash, slag, and silica fume with three different w/cm ratios: 0.40, 0.35, 0.30 to study the durability primarily concerning bridge deck. Results show that at higher w/cm ratio, both rapid chloride penetration and chloride diffusion depend mostly on supplementary cementitious materials. A combined freezing and thawing/salt-scaling test for a properly made test specimen is representative of real-life situation for bridge deck slab. The physical sulphate attack is minimal for HPC with low w/cm ratios. The present experimental study serves to establish a basis for the future optimisation of HPC mixture proportions as well as test methods through critical durability evaluations.

Influence of Slag Fineness on Durability of High-Performance Concrete

This research focuses on investigating the high performance concrete durability containing slag with different fineness and dosage. For this purpose, the 28-day compressive strength, chloride ion penetration, and frost resistance were investigated, with slag surface area 420m2/kg, 530m2/kg, 610m2/kg, and 720m2/kg, and replacement percentage 0%, 20%, 40%, and 60%, respectively. It was found that chloride ion penetration resistance were affected by the fineness and dosage of slag, and concrete frost resistance property was mainly controlled by dosage of slag rather than the fineness, and the 28-day compressive strength increased with slag incorporation.

Strength, permeability and shrinkage cracking of silica fume and metakaolin concretes

Using mineral admixtures as cement replacement substance in concrete has a tendency to increase by the future in order to provide greater sustainability in construction industry. This paper investigates the effectiveness of metakaolin (MK) and silica fume (SF) on the mechanical properties, shrinkage, and permeability related to durability of high performance concretes. Mechanical properties were evaluated by means of compressive and splitting tensile strength. Water sorptivity and gas permeability tests were carried out to find out the permeation characteristics of the concretes due to the incorporation of MK and SF. Shrinkage behavior of the concretes with and without mineral admixtures were dealt through measurements of free shrinkage strains and weight loss of the specimens due to drying. Moreover, crack formation and propagation of the restrained specimens were observed to better understanding the effect of MK or SF incorporation on the restrained shrinkage properties. For concrete production, replacement levels of 5% and 15% of MK or SF by the weight of cement were assigned. Water-to-cementitious (w/cm) material ratios of 0.25 and 0.35 were used in production of concrete. The design strength level ranging from75 to 86MPa was achieved. Test results revealed that replacement level of MK and SF had significant effects on the mechanical and especially durability characteristics of high performance concretes.

Analysis on the Correlations between Preservatives and the Durability of High Performance Structural Concretes

Concrete is the most consumed building material worldwide today, which durability has been paid close attentions for a long time. Currently，the design lifetime of many buildings is over 100 years. At present, many projects adopt preservatives to extend the durability of concrete. the paper makes contrastive studies on mechanical properties, ASTM flux, RCM chloridion diffusion, Permit in situ chloridion permeability, Autoclam water absorption, and freezing & thawing resistance between preservatives-added and non-preservative concretes at different typical strengths; and concludes correlations between the preservatives at different strengths and the durability of concrete, thus to evaluate the influence of various preservatives on the durability of high-performance concrete.

Sensitivity Analysis for Durability of High Performance Concrete Containing Nano-particles based on Grey Relational Grade

There are many effect factors of mix proportion on anti-permeability and anti-freezing durability of high performance concrete containing nano-particles, such as the dosage of cement, nanomaterials, mineral fine admixture, chemical admixture and the value of water-binder ratio and sand ratio. The aim of this study was to evaluate the effect of these effect factors on durability of high performance concrete containing nano-particles and find out the main factors. Applying grey relational analysis method, the relational grades between the effect factors and diffusion coefficient of Cl-, and the relational grades between the effect factors and anti-freezing durability coefficient of high performance concrete containing nano-particles were calculated. Besides, the sequence results of influencing degree of the factors to affect the anti-permeability and freezing-thawing resistance were obtained. The results indicate that water-binder ratio, dosage of cement and dosage of nano- particles have the greatest influence on chloride permeability and freeze-thaw resistance of high performance concrete containing nano- particles among the 7 selected parameters of design of mix proportion. In order to improve anti-permeability of Cl- and freeze-thaw resistance of high performance concrete containing nano-particles, water-binder ratio, the dosage of cement and nano-materials must be controlled strictly. It had better decrease water-binder ratio and the dosage of cement, besides increase the dosage of nano-materials.

Study on durability of high performance concrete with industrial wastes

Study on durability of high performance concrete with industrial wastes

Effect of Steel Slag Powder on the Durability of High Performance Concrete

dvanced mineral admixtures can lead to economical high performance concrete with enhanced durability and reduced cement content. When super fine steel slag powder is mixed into concrete as active admixture, resistance to abrasion and resistance to chloride penetration are improved as well as workability and mechanical properties of the concrete. Resistance to abrasion of steel slag concrete is measured and resistance to chloride penetration is also determined by the method of NEL and ASTM C1202 in this paper. Result shows that compound mineral admixtures as partial replacement for Portland cement in mortar enhance abrasion resistance. Mixing mineral admixture is an effective means for controlling the chloride permeability. Concrete specimens prepared with compound mineral admixture with steel slag powder and blast furnace slag powder has very low permeability.

Influence of Lightweight Aggregate on Durability of High Performance Concrete

High performance concrete (HPC) with a water/cement ratio (w/c) of 0.32 and different lightweight aggregate (LWA) contents (0%, 25%, 50%, 75%, 100%) were prepared, and the influence of LWA on concrete frost-resistance and impermeability at different ages were studied, as well as the hydration degree, hydrated product, pattern and pore structure of the paste around aggregate. The results show that, by replacing normal weight aggregate (NWA) with 50% and 100% volume contents of pre-wetted LWA respectively, the chemical bound water of the cement paste surrounding aggregate are increased 12.1% and 22.7% as compared to concrete mixed without LWA. And at 28 days, lightweight aggregate concrete has the highest Ca(OH)2 content, whereas the 90-day Ca(OH)2 content of normal weight concrete is the highest. This proves that, with the increase of LWA content in concrete, both of the internal curing effect of pre-wetted LWA and secondary hydration effect of fly ash (FA) are strengthened, this can also be verified by the SEM study. Furthermore, the pore structure of the cement paste around aggregate can be improved consequently. The performance of frost-resistance of HPC can be improved by mixing LWA, the 90 day-frost-resistance of lightweight aggregate concrete is about 2.5 times of that of concrete mixed without LWA. The influence of LWA on the impermeability of HPC is different from normal concrete. When LWA content is more than 50%, the HPC impermeability decreased obviously, however at later age the difference between them becomes minor.

Analysis of durability of high performance concrete using artificial neural networks

This study aims to determine the influence of the content of water and cement, water–binder ratio, and the replacement of fly ash and silica fume on the durability of high performance concrete (HPC) by using artificial neural networks (ANNs). To achieve this, an ANNs model is developed to predict the durability of high performance concrete which is expressed in terms of chloride ions permeability in accordance with ASTM C1202-97 or AASHTO T277. The model is developed, trained and tested by using 86 data sets from experiments as well as previous researches. To verify the model, regression equations are carried out and compared with the trained neural network. The results indicate that the developed model is reliable and accurate. Based on the simulating durability model built using trained neural networks, the optimum cement content for designing HPC in terms of durability is in the range of 450–500 kg/m 3. The results also revealed that the durability of concrete expressed in terms of total charge passed over a 6-h period can be significantly improved by using at least 20% fly ash to replace cement. Furthermore, it can be concluded that increasing silica fume results in reducing the chloride ions penetrability to a higher degree than fly ash. This study also illustrates how ANNs can be used to beneficially predict durability in terms of chloride ions permeability across a wide range of mix proportion parameters of HPC.

Strength and Durability of High Performance Concrete Using Artificial Sand

Strength and Durability of High Performance Concrete Using Artificial Sand

Durability Performance of Bridge Concretes, Part I: High Performance Concrete (HPC)

Abstract A study was undertaken on the durability of high performance cocrete (HPC) mixtures produced using locally available materials in the State of Missouri. Eighteen (18) mixtures were categorized as HPC. 30 % fly ash replacement by cement weight was utilized in the HPC mixtures, and ground granulated blast-furnace slag (GGBFS) was also substituted by 5 % of the cement for some mixtures. The mixtures included locally available limestone, trap rock, and river gravel as coarse aggregate. The mixtures of HPC without cement replacement displayed higher strength development at the end of 56 days. The compression strength development of the mixtures produced with locally available dolomitic limestone performed superior relative to other mixtures. All the mixtures performed poorly under 300 freezing and thawing cycles, except the control mixtures. The samples in which GGBFS was utilized performed poorly relative to the other samples. Similar poor performance was obtained from the same samples in chloride permeability tests.

An approach to optimizing mix design for properties of high-performance concrete

Laboratory and in situ test results reveal that the densified mixture design algorithm (DMDA) can be used to produce high-performance concrete (HPC) of good durability and high workability. The water-to-solid (W/S) weight ratio is known to have significant influence on the volume stability of concrete. This paper discusses strength of f′c>56 MPa, slumps of 230–270 mm, effect of the W/S ratio on the development of strength and durability of HPC at both fresh and hardened states. In addition to the water-to-cement (W/C) ratio and water-to-binder (W/B) ratio, the W/S ratio also has a significant effect on the performance of concrete. The utilization of fly ash and slag has been proven beneficial to the rheology of HPC in enhancing its strength development and durability.

Bending and Punching Shear Strength of Fiber-Reinforced Glass Concrete Slabs

♣ Post-doctoral research fellow, Center for Advanced Cement-Based Materials, Northwestern University. He received his MS and BS in solid mechanics from PRC, and his PhD from the Hong Kong University of Science and Technology. His research interests include fracture mechanics of concrete and fiber-reinforced concrete, durability of high performance concrete, extrusion technology and finite element method.

Effect of Curing Methods on Durability of High-Performance Concrete

Many state departments of transportation are currently either using high-performance concrete (HPC) or developing new mix proportions for the application of HPC to transportation structures, with emphasis on bridge decks. However, many state engineers have observed that curing methods and conditions in the field affect the behavior of HPC structures. Moreover, little is known about the effect of curing on the long-term durability of HPC. Therefore, it is necessary to understand the behavior of HPC under various curing conditions and durations and the effect of pozzolanic material such as fly ash and silica fume on rapid chloride permeability (RCP). These factors were studied as part of a project for the New Jersey Department of Transportation to develop and implement mix design and technical specifications for HPC transportation structures such as pavements and bridges. Several mixes were tested, and the best mix was selected on the basis of strength and shrinkage test performance. The long-term durability was assessed by tests for RCP, creep, and freeze–thaw behavior. Moreover, the effect on HPC of four curing methods—moist curing, air-dry curing, burlap wrap, and curing compound—was investigated. Moist-cured cylinders performed better than those cured with other methods, and a minimum of 14 days of cure was required for HPC to attain its full strength.

Fibers, Percolation, and Spalling of High-Performance Concrete

While the strength and durability of high-performance concretes (HPCs) are often greatly superior to conventional concretes under ambient conditions, their failure is sometimes rapid and dramatic during exposure to a fire, characterized by the explosive spalling of layers from the exposed concrete surface. This failure mode is rarely encountered in conventional concretes of higher water to cement ratios. In these concretes, it is suggested that the interfacial transition zones (ITZs) surrounding each aggregate particle provide a convenient escape route for the vapor built up during the thermal exposure. In HPC, these ITZ regions are thinner and not percolated, but can be repercolated by the addition of just a few (0.2% to 0.5% by volume) fibers. This study conducted simulations to determine the relative efficiency of different length fibers in creating a percolated network and to investigate the effects of aggregate volume fraction and gradation on ITZ percolation.

Durability of high performance concrete in magnesium brine

The durability of six concretes exposed to magnesium brine was monitored for 24 months. These concretes incorporated ground granulated blast furnace slag, silica fume, and fly ash. The Young's moduli, chloride penetrations, and median pore diameters were measured. There was a cyclic nature to these properties due to the complicated interaction of hydration with magnesium, chloride and sulfate attack. Mineral admixtures, in combination with a long initial cure, provided the most durable concrete. Concrete with 65% slag had the best overall durability to the brines tested.

Durability of High Performance Concrete

Durability of High Performance Concrete