scholarly journals Functional Properties of a Pitch-Based Carbon Fiber–Mortar Composite as a Thin Overlay for Concrete Pavement

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2753
Author(s):  
Jun Seok Lee ◽  
Inkyu Rhee
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Carbon Fiber ◽  
Fiber Strength ◽  
Low Cost ◽  
Cementitious Materials ◽  
Concrete Pavement ◽  
Control Specimen ◽  
Freezing And Thawing ◽  
Adhesion Performance

This experimental study investigated the utility of a pitch-based carbon fiber–mortar composite, which could replace polyacrylonitrile carbon fiber, as a thin overlay for concrete pavement. The objective was to explore the utility of the low-cost carbon fiber, which was produced via a melt-blown method, i.e., blowing at high pressure after melting the pitch residue following crude oil purification. The mechanical properties, durability, and thermal properties of the pitch-based carbon fiber were explored to maximize strength, durability, functionality, and economy by using micro-sized fibers that are closer in size to the constituents of cementitious materials. Melt-blown pitch-based carbon fiber has low individual fiber strength but generally excellent thermal conductivity. Thermal conductivity tests were conducted on mortar panels (560 mm × 560 mm; thickness = 25, 40 or 60 mm) containing 0, 0.4, 0.5 or 0.6 wt % pitch-based carbon fiber. The absolute thermal conductivity tended to improve with higher wt % of pitch-based carbon fiber, in the range of 9~11 W/°C. However, thermal conductivity tended to be lower under the 0.6 wt % condition, possibly due to the effect of dispersion. Compressive strength degradation was tested over 350 cycles of freezing and thawing: the strength of the 0.4, 0.5 or 0.6 wt % samples was 91, 89, and 82%, respectively, relative to the control specimen (0 wt %). Thus, all specimens had a compressive strength of 80% or more after 350 cycles compared to the control specimen. To test the adhesion performance for new thin overlays and old concrete surfaces, concrete cylinders (100 × 200 mm; thickness = 10 mm) were cut at an angle of 46 degrees, and the pitch-based carbon fiber-mortar composite was used to bond the various sections. The bond strength of the test specimens was more than twice that of the reference specimen.

Carbon fiber reinforced tin-superconductor composites

1989 ◽  
Vol 4 (6) ◽  
pp. 1339-1346 ◽  
Author(s):  
C. T. Ho ◽  
D. D. L. Chung
Keyword(s):  
Thermal Conductivity ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Carbon Fiber ◽  
Carbon Fibers ◽  
Tensile Modulus ◽  
Tensile Load ◽  
Tensile Fracture ◽  
Fiber Direction ◽  
Continuous Carbon Fiber

Unidirectional and continuous carbon fiber tin-matrix composites were used for the packaging of the high-temperature superconductor YBa2Cu3O7–δ by diffusion bonding at 170 °C and 500 psi. Tin served as the adhesive and to increase the ductility, the normal-state electrical conductivity, and the thermal conductivity. Carbon fibers served to increase the strength and the modulus, both in tension along the fiber direction and in compression perpendicular to the fiber layers, though they decreased the strength in compression along the fiber direction. Carbon fibers also served to increase the thermal conductivity and the thermal fatigue resistance. At 24 vol. % fibers, the tensile strength was approximately equal to the compressive strength perpendicular to the fiber layers. With further increase of the fiber content, the tensile strength exceeded the compressive strength perpendicular to the fiber layers, reaching 134 MPa at 31 vol. % fibers. For fiber contents less than 30 vol. %, the compressive ductility perpendicular to the fiber layers exceeded that of the plain superconductor. At 30 vol. % fibers, the tensile modulus reached 15 GPa at room temperature and 27 GPa at 77 K. The tensile load was essentially sustained by the carbon fibers and the superconducting behavior was maintained after tension almost to the point of tensile fracture. Neither Tc nor Jc was affected by the composite processing.

Performance of Stabilized Earth with Wheat Straw and Slag

MRS Advances ◽  
2020 ◽  
Vol 5 (25) ◽  
pp. 1285-1294 ◽  
Author(s):  
W Benhaoua ◽  
K. Grine ◽  
S. Kenai
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Low Cost ◽  
Construction Material ◽  
Soil Samples ◽  
Capillary Absorption ◽  
Wetting And Drying ◽  
Environment Friendly ◽  
Granulated Blast Furnace Slag ◽  
Local Soil

ABSTRACTStabilized earth is a very ancient material that has been used in many countries as a low cost, environment friendly construction material. However, its durability under humid environments is low. Stabilization using cement, lime and natural fibres could enhance its durability and lowers the risk of cracking. This paper presents an experimental investigation into the performance of stabilised local soil by either, cement mixed with a proportion of granulated blast furnace slag (GBFS) /or straw naturel fibres. Unconfined compressive strength (UCS), shrinkage, wetting and drying, capillary absorption and thermal conductivity tests were performed on both untreated soil samples and stabilised soil samples. The results show that stabilising the soil with cement and GBFS increased both compressive strength, durability, thermal conductivity and decreased the capillary absorption and the shrinkage. The addition of natural wheat fibres increased the capillary absorption but leads to a decrease in the thermal conductivity and to a further reduction in the shrinkage and hence a better insulating less prone to cracking material.

scholarly journals Recycling of a Concrete Pavement after over 80 Years in Service

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2262 ◽  
Author(s):  
Tomasz Rudnicki ◽  
Robert Jurczak
Keyword(s):  
Compressive Strength ◽  
Fatigue Testing ◽  
Heavy Traffic ◽  
Concrete Pavement ◽  
Petrographic Analysis ◽  
Concrete Aggregate ◽  
Freezing And Thawing ◽  
Traffic Loading ◽  
Freeze Thaw ◽  
Renewal Project

This article presents the results of fatigue testing and assessment of the mechanical and physical properties of the concrete pavement of the A6 motorway, which was put in service in 1938. After 82 years of operation under heavy traffic loading conditions, the pavement was fully recycled by crushing of the existing concrete and reuse of the reclaimed material in the new courses of pavement placed as part of the motorway renewal project. The main objective of this research was to determine the properties of the tested concrete, including compressive strength, water absorption and freeze-thaw resistance after 150 cycles of alternate freezing and thawing. The resistance of the concrete to the action of de-icing products was also checked. The article also presents the results of petrographic analysis of the aggregates. Additionally, concrete sampled from the pavement was evaluated for freeze-thaw resistance in relation to the determined porosity characteristics. The tested concrete, which was subjected to over 80 years of traffic loading on the A6 motorway, was found to meet the highest requirements as currently applied for the extra heavy-duty pavements. With a compressive strength value in excess of 50 MPa, the tested concrete can be rated at least CC40, according to EN 13877-2:2013-08. The samples were found to satisfy the freeze-thaw resistance requirements of an F150 rating. The air void analysis showed that the analyzed concrete contained 1.6% of micropores, i.e., air voids smaller than 300 μm (A300). The spacing factor, in turn, was below 0.200 mm (L = 0.185 mm). The example of the A6 motorway renewal project served to demonstrate that reclaimed concrete aggregate, obtained by crushing the entire pavement, can be used for production of the new pavement courses.

scholarly journals Compressive Strength Characteristics of Cemented Tailings Backfill with Alkali-Activated Slag

2018 ◽  
Vol 8 (9) ◽  
pp. 1537 ◽  
Author(s):  
Gaili Xue ◽  
Erol Yilmaz ◽  
Weidong Song ◽  
Shuai Cao
Keyword(s):  
Compressive Strength ◽  
Mine Tailings ◽  
Low Cost ◽  
Cementitious Materials ◽  
Cementitious Material ◽  
Solid Wastes ◽  
Fine Grained ◽  
Activated Slag ◽  
The Relationship ◽  
Alkali Activated

With the use of glauberite mineral (GM) and sodium hydroxide (SH) alkaline catalysts to stimulate slag powder’s internal cementation activity and incorporate the two fine-grained solid wastes, such as quicklime (Q) and desulfurized ash (DA), a new cementitious material suitable for mine tailings was developed to replace traditional ordinary Portland cement (OPC) for reducing cement-related costs. A series of uniaxial compressive strength (UCS) tests were carried out on cemented tailings backfill (CTB) samples containing different activators. The results showed that (1) the highest UCS values of 14-day and 28-day cured CTB samples were 1.259 MPa and 2.429 MPa, respectively, and the effect of different activator types was in the order of SH > GM > DA > Q and SH > GM > Q > DA; (2) the relationship between UCS and activator dosages followed the function y = ax3 − bx2 + cx − d. Compared with the OPC 32.5 R cemented samples, the minimum strength growth factor was 1.45, and the maximum reached 2.03; (3) the optimal proportion of DA slag formula was 4.5% or 5.0% Q, 19% DA, 2.5% GM, and 0.7% SH. The aforesaid new cementitious materials met the mine’s UCS requirements with a relatively low cost (17.04–17.20 €/ton) and solved the stacking problem of solid wastes on the surface well. Ultimately, this study provides a useful reference for the development of mineral binders.

Environmentally Friendly Cellular Concrete for Wall Insulation

2013 ◽  
Vol 539 ◽  
pp. 271-275 ◽  
Author(s):  
Ya Qing Jiang ◽  
Jun Yang ◽  
Yun Chen
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Fly Ash ◽  
Mass Density ◽  
Polypropylene Fiber ◽  
Cementitious Materials ◽  
Dry Density ◽  
Insulation Material ◽  
Good Market ◽  
Cellular Concrete

Cellular concrete characterizes low mass density and low thermal conductivity is one of the durable and economic wall insulation materials which have good market prospects. The present paper investigated the composition of ternary cementitious materials, mixture design and production process of cellular concrete panel (CCP). Experimental results indicated that a higher compressive strength of CCP may be obtained by blended PⅡ52.5 Portland cement with pulverized low temperature clinker (PLWC) made of water treatment sludge and fly ash in the mass ratio of 0.70: 0.15: 0.15. CCP with dry density of 226 kg/m3, thermal conductivity of 0.056 W/ (m•K), compressive strength of 0.6 MPa and water absorption ratio of 7.6 vol. % was modified by high range water reducer, polypropylene fiber and water resistant agent. Mathematic models for controlling temperature of mixing water and for calculation quantity of gas forming admixture were established. Insulated moulds were specially designed for taking advantage of hydration heat of cement to speed up moulds turnover. Meanwhile, internal microcrack of CCP was avoided. CCP incorporating PLWC and fly ash may be used as external insulation material of walls.

scholarly journals Feasibility Tests on Concrete with Very-High-Volume Supplementary Cementitious Materials

2014 ◽  
Vol 2014 ◽  
pp. 1-11
Author(s):  
Keun-Hyeok Yang ◽  
Yong-Su Jeon
Keyword(s):  
Compressive Strength ◽  
Weight Ratio ◽  
High Volume ◽  
Cementitious Materials ◽  
Positive Influence ◽  
Supplementary Cementitious Materials ◽  
Early Age ◽  
Freezing And Thawing ◽  
Strength And Durability ◽  
Very High

The objective of this study is to examine the compressive strength and durability of very high-volume SCM concrete. The prepared 36 concrete specimens were classified into two groups according to their designed 28-day compressive strength. For the high-volume SCM, the FA level was fixed at a weight ratio of 0.4 and the GGBS level varied between the weight ratio of 0.3 and 0.5, which resulted in 70–90% replacement of OPC. To enhance the compressive strength of very high-volume SCM concrete at an early age, the unit water content was controlled to be less than 150 kg/m3, and a specially modified polycarboxylate-based water-reducing agent was added. Test results showed that as SCM ratio (RSCM) increased, the strength gain ratio at an early age relative to the 28-day strength tended to decrease, whereas that at a long-term age increased up toRSCMof 0.8, beyond which it decreased. In addition, the beneficial effect of SCMs on the freezing-and-thawing and chloride resistances of the concrete decreased atRSCMof 0.9. Hence, it is recommended thatRSCMneeds to be restricted to less than 0.8–0.85 in order to obtain a consistent positive influence on the compressive strength and durability of SCM concrete.

scholarly journals Thermal resistance of raffia palm reinforced concrete

2021 ◽  
Vol 20 (1) ◽  
pp. 5-14
Author(s):  
Samson Olalekan Odeyemi ◽  
◽  
Zainab Tolu Giwa ◽  
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Thermal Resistance ◽  
Low Cost ◽  
Fibre Content ◽  
Natural Fibres ◽  
Fibre Reinforced Concrete ◽  
Control Specimen ◽  
Concrete Production ◽  
Palm Fibre

There are increasing interests in the usage of natural fibres as reinforcing component for concrete production due to their enormous properties such as low cost, its abundance and availability. This research examined the thermal resistance of Raffia palm fibre reinforced concrete. In this study, 0% to 1% fibre content by weight of cement were incorporated in concrete and their compressive strength were tested after heating. A total number of 36 cubes were prepared, cured and tested at 28 days. Concrete cubes with 0% fibre was used as control specimen. The cubes’ compressive strengths were determined at 0 0C, 556 0C and 659 0C at 0 minutes, 5 minutes and 10 minutes respectively. The result revealed that workability of the concrete declined with a rise in the percentage of raffia palm. There is also a substantial surge in the compressive strength of raffia palm fibre reinforced concrete cubes (RPFRC) compared to the control concrete samples. The compressive strength of the concrete cubes decreased with the rise in temperature for the entire samples tested. It was concluded that a rise in the proportion of fibre in the concrete enhanced their compressive strengths when subjected to heat.

scholarly journals Stabilization/Solidification of Zinc- and Lead-Contaminated Soil Using Limestone Calcined Clay Cement (LC3): An Environmentally Friendly Alternative

2020 ◽  
Vol 12 (9) ◽  
pp. 3725 ◽  
Author(s):  
Vemula Anand Reddy ◽  
Chandresh H. Solanki ◽  
Shailendra Kumar ◽  
Krishna R. Reddy ◽  
Yan-Jun Du
Keyword(s):  
Compressive Strength ◽  
Contaminated Soil ◽  
Contaminated Soils ◽  
Low Cost ◽  
Construction Material ◽  
Environmentally Friendly ◽  
Cementitious Materials ◽  
Low Carbon ◽  
Untreated Soil ◽  
Calcined Clay

Due to increased carbon emissions, the use of low-carbon and low-cost cementitious materials that are sustainable and effective are gaining considerable attention recently for the stabilization/solidification (S/S) of contaminated soils. The current study presents the laboratory investigation of low-carbon/cost cementitious material known as limestone-calcined clay cement (LC3) for the potential S/S of Zn- and Pb-contaminated soils. The S/S performance of the LC3 binder on Zn- and Pb-contaminated soil was determined via pH, compressive strength, toxicity leaching, chemical speciation, and X-ray powder diffraction (XRPD) analyses. The results indicate that immobilization efficiency of Zn and Pb was solely dependent on the pH of the soil. In fact, with the increase in the pH values after 14 days, the compressive strength was increased to 2.5–3 times compared to untreated soil. The S/S efficiency was approximately 88% and 99%, with increase in the residual phases up to 67% and 58% for Zn and Pb, respectively, after 28 days of curing. The increase in the immobilization efficiency and strength was supported by the XRPD analysis in forming insoluble metals hydroxides such as zincwoodwardite, shannonite, portlandite, haturite, anorthite, ettringite (Aft), and calcite. Therefore, LC3 was shown to offer green and sustainable remediation of Zn- and Pb-contaminated soils, while the treated soil can also be used as safe and environmentally friendly construction material.

scholarly journals Utilization of Corn Cobs Ash as Cementitious and Binary Cementitious Materials in Concrete and Cement-based Composites: A Review

2021 ◽  
pp. 26-42
Keyword(s):  
Compressive Strength ◽  
Energy Savings ◽  
Low Cost ◽  
Cementitious Materials ◽  
Pulse Velocity ◽  
Partial Replacement ◽  
Hardened Concrete ◽  
Biomass Ash ◽  
Operational Conditions ◽  
Corn Cobs

This paper reviews the utilization of corn cobs ash (CCA) as pozzolanic, cementitious, and binary cementitious materials in concrete. CCA is the grey-to-brown, inorganic or heterogeneous residual material derived from the high- temperature incineration or combustion of corn cobs (CC). Despite the typical problematic nature of biomass ash, the chemical composition of CCA renders it a potential pozzolanic material. Therefore, numerous studies have critically examined the process technologies and operational conditions for CCA production and its application as a partial replacement for cement in concrete. Other studies have extensively characterized the physicochemical, morphological, microstructure, and thermal properties of CCA through various analytical techniques. Potential pozzolanic materials must meet the condition: SiO2 + Al2O3 + Fe2O3 ≥ 70%, according to ASTM C618, to which CCA complies satisfactorily. Hence, the use of CCA as a replacement for cement has been investigated over the years. Findings indicate that the partial replacement of cement with CCA decreases compressive strength, thermal conductivity, ultrasonic pulse velocity, and density of the hardened concrete at normal temperatures. Nevertheless, the thermal treatment (calcination) of CCA and extended curing enhances compressive strength owing to higher silica content and extended surface area. Besides, the partial replacement of cement with CCA enhances the insulation properties of mortar, which improves thermal comfort, costs and energy savings in buildings. Hence, the partial replacement of cement with CCA provides an environmentally friendly, low cost, and sustainable approach for valorizing CC residues whilst addressing CO2 emissions in construction.

scholarly journals Effect of Expanded Perlite Aggregate Size on Physical and Mechanical Properties of Ultra Lightweight Concrete Produced with Expanded Perlite Aggregate

2019 ◽  
Author(s):  
Mucip Tapan ◽  
Celil Engin
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Water Absorption ◽  
Bending Strength ◽  
Lightweight Concrete ◽  
Unit Weight ◽  
Ultra Sound ◽  
Expanded Perlite ◽  
Freezing And Thawing ◽  
Freezing And Thawing Cycles

In this study, ultra-light weight concrete (ULWC) with heat-insulating properties is produced by using different size expanded perlite aggregates and various admixtures. The compressive strength, 4 point bending strength, freezing and thawing resistance, water absorption, dry unit weight, ultra sound velocities and thermal conductivity of the samples were determined by applying appropriate tests. The effect of different size expanded perlite aggregate on the properties of ULWC were also investigated in this study and it was found that as the expanded perlite aggregate diameter increased, the void volume uniformity, water absorption percentage and freezing-thawing resistance increased while the unit volume weight of ULWC samples, ultrasound speed velocities, thermal conductivity and compressive strength were decreased. The changes in the masses and compressive strength of ULWC samples subjected to freezing and thawing cycles were examined. The compressive strength loss was found to be between 5 % and 47 % while the weight loss was between 1 % and 3.5 % after 15 freezing and thawing cycles. Finally, the effects of the admixtures on the fresh properties of ULWC were examined and it was determined that the use of 4.5 kg of air-entraining material in one cubic meter of concrete mix is the most ideal ratio and the use of more than 0.01 % by volume of polypropylene fiber is caused settlements in fresh concrete mixtures.

Sign in / Sign up

Export Citation Format

Share Document