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In this study, two industrial wastes – circulating fluidized bed combustion co-fired fly ash (CFA) and ground granulated blast-furnace slag (GGBS) – were used as green materials instead of cementitious materials in controllable low strength material (CLSM). CLSM was used to backfill the pavement. CLSM should meet the compressive strength requirements of the CLSM specification (under 8.24 MPa), and it had the self-consolidating characteristics of fluidized concrete. In order to comply with the characteristics of self-consolidation, a mix design including superplasticizers, adhesives, and accelerators were used to ensure that the proportion could meet the requirements of both CLSM and the self-consolidating properties. The test methods included the slump flow test, ball drop test, strength activity index, compressive strength, mercury intrusion porosimetry, chlo-ride migration test, and scanning electron microscope. A water/cement ratio of 0.85 was used as the mix design for the CLSM requirements. The CFA and GGBS used in CLSM could replace 78 wt.% of the cement, and CLSM could effectively meet the requirements of the workability, strength and microscopic properties.

This study used silicon carbide sludge (SCS) to prepare lightweight foaming geopolymer materials (FGPs) by the direct foaming method. Results showed that when the SCS replacement level was 10%, the bulk density of the lightweight FGPs with added foaming agent amounts of 0.5% and 2.0% was 0.59 and 0.49 g/cm3, respectively; at a curing time of 28 days, the lightweight FGPs with amounts of added foaming agent of 0.5% and 2.0% had bulk densities that were 0.65 and 0.58 g/cm3, respectively. When the SCS replacement level was 10%, and the amount of added foaming agent was 2.0%, the porosity ratio of the lightweight FGP increased from 31.88% to 40.03%. The mechanical strength of the lightweight FGPs with SCS replacement levels of 10% and 20% was 0.88 and 0.31 MPa, respectively. Additionally, when the amount of foaming agent increased to 2.0%, the thermal conductivity of the lightweight FGPs with SCS replacement levels of 10% and 20% were 0.370 and 0.456 W/m⋅K, respectively. When the curing time was 1 day, and the amount of added foaming agent was 0.5%, the reverse-side temperature of the lightweight FGPs with SCS replacement levels of 10% and 20% were 286 and 311 °C, respectively. The k value of the O2 reaction decreased from 2.94 × 10−4 to 1.76 × 10−4 because the reaction system was affected by the presence of SiC sludge, which was caused the reaction to consume O2 to form CO2. The results have been proposed to explain that the manufactured lightweight FGPs had a low thermal conductivity (0.370–0.456 W/m⋅K). Therefore, recycling of silicon carbide sludge in lightweight foaming geopolymer materials has potential as fire resistance material for the construction industry.

The aim of the article is to analyze the structure and mechanical properties in terms of the cracking mechanics of geopolymer composites based on fly ash and river sand, as well as metakaolin and river sand with three types of reinforcement material: glass fiber, carbon fiber, and aramid fiber, in terms of their use in additive manufacturing. Geopolymer composites were reinforced with fibers in a volume ratio of 0.5%, 1.0%, and 2.0%. Subsequently, these samples were subjected to bending strength tests in accordance with the European standard EN 12390-3. The addition of fibers significantly improved the bending strength of all composites made of metakaolin and sand. The reinforcement with aramid fiber in the amount of 2.0% resulted in more than a 3-fold increase in strength compared to the reinforcement-free composites. An analysis of the morphology of the fibers was carried out on the basis of photos taken from an electron microscope. The correct addition of fibers changes the nature of the fracture from brittle to more ductile and reduces the number of cracks in the material.

The research described in this article was aimed at determining the influence of hydraulic additives on the foaming process and the stability of the produced geopolymer foams. These foams can be used as insulation materials to replace the currently commonly used insulations such as expanded polystyrene or polyurethane foams. Geopolymers have low thermal conductivity, excellent fire- and heat-resistant properties, and have fairly good mechanical properties. Research on foamed materials shows that they have the highest class of fire resistance, therefore, they are most often used as insulation products in construction. Geopolymer foams were made of aluminosilicate materials (fly ash) and foaming agents (H2O2 and Al powder), and the stabilizers were gypsum and portland cement. Additionally, surfactants were also used. It was found that better foaming effects were obtained for H2O2—it is a better foaming agent for geopolymers than Al powder. When using a hydraulic additive—a stabilizer in the form of cement—lower densities and better insulation parameters were obtained than when using gypsum. Portland cement is a better stabilizer than gypsum (calcium sulfates), although the effect may change due to the addition of surfactants, for example.

In this study, ultra-fine spherical particles of silica fume and reactive ultra-fine fly ash were added to a mixture of commercial ultra-high-performance grout (UHPG) with the aim of enhancing the rheological properties, compressive strength, compactness, and permeability. This commercial UHPG study was conducted in collaboration with Triaxis Corporation (Changsha city, Hunan province, China). A water-to-binder ratio of 0.21 and a binder-to-fine aggregates ratio of 1.17 were used as fixed parameters, and the binders were a combination of type-II Portland cement, sulphoaluminate cement, silica fume, and reactive ultra-fine fly ash (RUFA). Polycarboxylate superplasticizer powder was used to control the rheology. The results revealed excellent compressive strength, volume stability, and resistance to chloride penetration. Mercury intrusion porosimetry and scanning electron microscopy tests revealed that the medium-sized RUFA particles with small silica fume particles completely filled the spaces between large cement particles to achieve optimal densification. This mixture also produced dense hydration and calcium-silicate-hydrates colloids, which filled the microstructures of the UHPG resulting in excellent engineering properties and durability. This commercially available UHPG mix responded to excellent compressive strengths approaching 120 MPa and exhibited good workability with a loss of slump-flow rate up to 33% after 60 min. It also exhibited very low abrasion resistance (0.5%), stable shrinkage and expansion rates (stabilization over 10 days), very low chloride diffusion coefficient (less than 0.1 × 10−14 m2/s) with a denser microstructure. This commercial UHPG (UHPG-120) has been developed to meet the needs of the market.

This study was aimed to investigate calcium fluoride sludge waste resource reuse, and explore the feasibility of calcium fluoride sludge in cement-based materials used to replace the cement. The mechanical properties and durability of cement-based materials containing calcium fluoride sludge were performed using resistance test, absorption test, initial surface absorption tests, dry shrinkage test, compressive strength test, mercury intrusion porosimetry and scanning electron microscopy observation. The results indicated that partially replacing cement with calcium fluoride sludge improved the compressive strength, permeability and pore-structure, as well as 10% replacement of cement seems to give superior mechanical properties and durability due to the denser microstructures. Such dense microstructures observed in scanning electron microscopy images and narrow pore size distribution determined by mercury intrusion porosimetry.

The vigorous promotion of reuse and recycling activities in Taiwan has solved a number of problems associated with the treatment of industrial waste. Considerable advances have been made in the conversion of waste materials into usable resources, thereby reducing the space required for waste storage and helping to conserve natural resources. This study examined the use of non-alkali activators to create bonded materials. Our aims were to evaluate the feasibility of using ground-granulated blast-furnace slag (S) and circulating fluidized bed co-fired fly ash (F) as non-cement binding materials and determine the optimal mix proportions (including embedded fibers) with the aim of achieving high dimensional stability and good mechanical properties. Under a fixed water/binder ratio of 0.55, we combined S and F to replace 100% of the cement at S:F ratios of 4:6, 5:5, 6:4. Polypropylene fibers (L/d = 375) were also included in the mix at 0.1%, 0.2% and 0.5% of the volume of all bonded materials. Samples were characterized in terms of flowability, compressive strength, tensile strength, water absorption, shrinkage, x-ray diffraction (XRD) and scanning electron microscope (SEM) analysis. Specimens made with an S:F ratio of 6:4 achieved compressive strength of roughly 30 MPa (at 28 days), which is the 80% the strength of conventional cement-based materials (control specimens). The inclusion of 0.2% fibers in the mix further increased compressive strength to 35 MPa and enhanced composite properties.

In this study, we coated fine recycled concrete aggregate (FRCA) with fly ash, slag, or polyvinyl alcohol (PVA) (viscosity: 44–50 cps), replaced 25% of the natural fine aggregate in concrete with the coated FRCA, and examined the durability and microscopic properties of the flesh concrete and hardened concrete. We then examined the effects of the various types of coating as well as the thickness on the properties of concrete. Our test results indicate that coating FRCA with fly ash or PVA increases the workability of the fresh concrete, whereas slag coatings slightly reduce the workability. Slag coatings increased the compressive strength, splitting strength, and durability of specimens to a greater degree than do fly ash or PVA coatings, regardless of the water-cement ratio. Furthermore, thicker coatings were shown to produce better results. Scanning electron microscopy images and mercury intrusion porosimetry tests verified that specimens containing FRCA coated with slag resulted in superior engineering properties.

The main objective of this article is to develop ceramic-based materials for additive layer manufacturing (3D printing technology) that are suitable for civil engineering applications. This article is focused on fly ash-based fiber-reinforced geopolymer composites. It is based on experimental research, especially research comparing mechanical properties, such as compressive and flexural strength for designed compositions. The comparison includes various composites (short fiber-reinforced geopolymers and plain samples), different times of curing (investigation after 7 and 28 days), and two technologies of manufacturing (casted and injected samples&mdash, simulations of the 3D printing process). The geopolymer matrix is based on class F fly ash. The reinforcements were green tow flax and carbon fibers. The achieved results show that the mechanical properties of the new composites made by injection methods (simulations of 3D technology) are comparable with those of the traditional casting process. This article also discusses the influence of fiber on the mechanical properties of the composites. It shows that the addition of short fibers could have a similar influence on both of the technologies.

Recently, many people around the world have been concerned with environmental protection and sustainability. The goal of various countries&rsquo, research has been focused on how to regenerate existing resources. Circulation fluidized bed combustion (CFBC) technology is one of the emerging combustion technologies for electricity generation and produces more than 800,000 tons of CFBC fly ash (CFA) per year for combustion. CFA has been widely applied in cement additive, new building materials and cement-based materials. The goal of this study was to discuss the engineering properties of roller-compacted concrete containing CFA. Test subjects included compressive strength, flexural strength, absorption, setting time, unit weight, sulfate resistance, SEM microscopic observations and XRD ingredient analysis. Test results indicate the following: (1) using CFA as a substitute of fine aggregates up to 10 wt.% would improve the development of later flexural strength, (2) the increases in pre-pressure would increase the compressive strength and unit weight and decrease absorption, (3) using CFA would reduce the initial setting time by 30%&ndash, 60% and reduce the final setting time by 16%&ndash, 20%, (4) using CFA would reduce the absorption, (5) using CFA would reduce the unit weight by 0.5%&ndash, 2.8%, and the increases in pre-pressure would increase the unit weight by about 0.9%&ndash, 2.1%, (6) CaO in CFA helps to improve sulfate resistance, (7) scanning electron microscopy (SEM) observation shows that the increases in pre-pressure would reduce the pores, and (8) X-ray diffraction (XRD) analysis shows that the inclusion of CFA would increase the content of Ca(OH)2 in concrete.

The repair of damaged structures is a complicated problem in the construction industry and it is no uniform standard for evaluating the effectiveness of repair materials. Two different redispersible polymer powders, ethylene vinyl acetate (EVA) and polyvinyl acetate-vinyl carboxylate (VA/VeoVa), were added in the repair mortars with two water-cement ratios and three polymer-cement ratios. The effectiveness of repair materials was evaluated according to the physical, mechanical properties and micrographs. Testing program includes setting time, drying shrinkage, thermal expansion, compressive strength, tensile strength, flexural strength, bond strength, X-ray diffraction analysis, scanning electron microscopy observation. Test results show that the specimens with VA/VeoVa and w/c of 0.5 have highest compressive strength, tensile strength, flexural strength and bond strength. The specimen with EVA also has higher strength than control one at the age of 28 days. The drying shrinkage deformation of VA/VeoVa specimen is close to the control one. The specimens with VA/VeoVa have lower thermal expansion than EVA specimen when the water-cement ratio is 0.5 and there is no difference between EVA and VA/VeoVa specimens for the water-cement ratio of 0.6. The micrographs show that adding polymer powder can reduce the pore and improve the durability.

This study examined the permeability of concrete in which a portion of the cement was replaced with reactive ultra-fine fly ash (RUFA) or silica fume. RUFA is an industrial by-product from thermal power plants, with spherical particles ranging in size from 0.1 μm to 10 μm, which is smaller than the particles in conventional fly ash. In experiments, the water-to-binder ratio was fixed at 0.45, and various proportions of the cement (5 % or 10 %) were replaced with RUFA, silica fume, or a combination of the two (5 % RUFA + 5 % silica fume, or 8 % RUFA + 2 % silica fume). The inclusion of RUFA was shown to enhance workability and promote the pozzolanic reaction resulting in the formation of C-S-H colloids. The filling of pore structures by colloids increased the compactness and compressive strength of the specimens, and reduced dry shrinkage. The inclusion of RUFA was also shown to reduce chloride ion penetration and the non-steady-state migration coefficient, which are indicative of improved mechanical properties and reduced permeability. Overall, RUFA proved superior to silica fume as a cement replacement in terms of workability, permeability, and mechanical properties.

Our objective in this study was to promote the recycling of industrial by-products by combining ground granulated blast-furnace slag (G) and circulating fluidized bed co-fired fly ash (FA). We then added sodium silicate as an alkali activator (A) to a combination of G and FA (GFA) to create a novel cement-free cementitious material (AGFA). One of our main research aims was to explore the influence of the activator on GFA in terms of working and mechanical properties and drying shrinkage behavior. Hydration products were analyzed using XRD and SEM-EDS. The setting time of GFA was longer than that of AGFA, and the water absorption and fluidity were both higher. Adding sodium silicate to the GFA was shown to greatly improve mechanical properties through the formation of hydration products containing C–S–H, C-A-S-H, and C–N-A-S-H gels, which intertwined to form a dense microstructure. Compared to AGFA, the GFA was less affected by dry shrinkage, due to the expansive formation of ettringite (from anhydride) during the hydration process. Note that the reaction of the alkaline agent in AGFA with the anhydride in FA reduced the amount of ettringite that formed. The alkaline agent also promoted the depolymerization of vitreous G and FA particles, resulting in the formation of large quantities of gel, the process of which consumed much of the free water, resulting in further shrinkage. Further, it provides a good feasibility and application prospect in environmentally friendly building material of GFA and AGFA cementless composites and is expected to replace traditional cement-based composites.

In this study, it evaluated the effects of sand/aggregate (S/A) ratio on the flowability, strength, durability, and microstructures of self-compacting concrete (SCC). Testing was performed on specimens using five S/A ratios: 51%, 52%, 53%, 54%, and 55%. Slump flow tests, slump tests, and box tests were used to characterize the rheological properties of the concrete as well as the mechanical properties, including compressive strength, splitting strength, slant shear strength and ultrasonic pulse velocity. Durability was evaluated using tests of absorption, resistivity and initial surface absorption. Microstructures were examined using mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). The test results indicate that a higher S/A ratio improved flowability. A greater proportion of coarse aggregate (i.e., a decrease in S/A ratio) improved the mechanical properties by 10% compared to the control specimens (S/A ratio: 52%) at 56 days. A higher S/A ratio was shown to improve bonding capacity by enhancing the roughness of the particles and thereby increasing adhesion strength. A higher S/A ratio was also shown to improve the durability of the specimens by permitting denser packing; however, a higher S/A ratio resulted in a thinner interfacial transition zone. MIP analysis did not reveal a correlation between S/A ratio and the interfacial transition zone, whereas SEM photos indicated that a lower S/A ratio reduces the size of the interfacial transition zone.

For the sake of environmental protection and circular economy, cement reduction and cement substitutes have become popular research topics, and the application of green materials has become an important issue in the development of building materials. This study developed green pervious concrete using water-quenched blast-furnace slag (BFS) and co-fired fly ash (CFFA) to replace cement. The objectives of this study were to gauge the feasibility of using a non-cement binder in pervious concrete and identify the optimal binder mix design in terms of compressive strength, permeability, and durability. For filled percentage of voids by cement paste (FPVs) of 70%, 80%, and 90%, which mixed with CFFA and BFS as the binder (40 + 60%, 50 + 50%, and 60 + 40%) to create pervious concrete with no cement. The results indicate that the complete (100%) replacement of cement with CFFA and BFS with no alkaline activator could induce hydration, setting, and hardening. After a curing period of 28 days, the compressive strength with different FPVs could reach approximately 90% that of the control cement specimens. The cementless pervious concrete specimens with BFS:CFFA = 7:3 and FPV = 90% presented better engineering properties and permeability.

Fiber cementitious materials are composed of fibers, pozzolan and cementitious. Addition of fibers in cementitious materials may enhance its mechanical properties, particularly tensile strength, and ductility. This project is aimed to evaluate the mechanical properties of fiber cementitious materials which comprise fibers and silica fume in the mixes. Test variables include dosage of silica fume, mix proportions, steel fiber dosage and type. Compressive strength, direct tensile strength and splitting tensile strength of the specimen were obtained through tests. Test results indicate that the splitting tensile strength, direct tensile strength, strain capacity and ability of crack-arresting increase with increasing steel fiber and silica fume dosages. The optimum composite is the mixture with 5 % replacement silica fume and 2 % fiber volume. In addition, the nonlinear regression analysis was used to determine the best-fit relationship between mechanical properties and test parameters.

This study is aimed to evaluate the tensile strength and impact resistance of cementitious materials which comprise steel fibers and silica fume in the mixes. Material variables include water-binder ratio, dosage of silica fume, steel fiber length and dosage. A designed tensile strength was used to perform the direct tensile in this study. Test results indicate that the compressive strength, splitting tensile strength and direct tensile strength of specimens for fiber length of 60 mm are higher than that of 35 mm. The inclusion of fibers in specimens containing silica fume has higher compressive and tensile strength; and lower impact resistance than the specimens made with silica fume. Incorporation of steel fiber and silica fume in composites achieves significantly higher increase in compressive strength, splitting tensile strength, and direct tensile strength than only individual use of steel fiber or silica fume and decrease in impact resistance than only individual use of steel fiber. Finally, the proposed direct tensile testing method is suitable for determining the tensile strength of fiber reinforce cementitious materials and generating the tensile stress-strain curves easily.

The pore distribution in cement mortar, which is highly related to compressive strength and permeability, vary with water-cement ratios and curing periods. This study used magnetic resonance imaging (MRI) to observe the pore distribution. Compressive strength tests, the rapid chloride-ion permeability test, and electrical resistivity tests were performed to determine the influence of pore distribution on durability. The results reveal that lower water-cement ratios and longer curing periods contributes to fewer pores in mortar specimens. SEM images illustrated how this may be influenced by the rate at which the hydration product, C-S-H colloids, is generated. In addition, the results of durability testing indicate that porosity and compressive strength, total charge passed, and resistivity display linear relationships, as porosity increases, the total charge passed increases, resistivity decreases, and compressive strength declines. The linear regression determined that the R2 of all relationships exceeded 0.90, thereby demonstrating the feasibility of applying MRI to assess the durability of concrete.

In this study, the different proportions of co-fired fly ash and ground granulated blast-furnace slag were used to fully replace the cement as non-cement blended materials in a fixed water-cement ratio. The recycled fine aggregates were replaced with natural fine aggregates as 10%, 20%, 30%, 40% and 50%. The flowability, compressive strength, water absorption and scanning electron microscope observations were used as the engineered indices by adding different proportions of recycled fine aggregates. The test results indicated that the fluidity cannot be measured normally due to the increase in the proportion of recycled fine aggregates due to its higher absorbability. In the compressive strength test, the compressive strength decreased accordingly as the recycled fine aggregates increased due to the interface structure and the performance of recycled aggregates. The fine aggregates and other blended materials had poor cementation properties, resulting in a tendency for their compressive strength to decrease. However, the compressive strength can be controlled above 35 MPa of the green non-cement blended materials containing 20% recycled aggregates.

This study analyzed the feasibility of ground-granulated blast-furnace slag (GGBS) and ground-granulated basic oxygen furnace slag (GGBOS) blended cements according to the standard specifications of ASTM C821-09 and ASTM C595/C595M-13. Through tests, this study verified that GGBOS can be used as alkali activators for GGBS and that the mixture proportions of S4I6 and S5I5 correspond with the physical and chemical requirements specified in ASTM C595/C595M-13. Among S3I7, S4I6, and S5I5, the mixture proportion of S4I6 exhibited the highest performance by reaching 90% of the compressive strength of ordinary Portland cement mortar.

This study focuses on the effect of the amount of silica fume addition and volume fraction of steel fiber on the engineering properties of cementitious materials. Test variables include dosage of silica fume (5% and 10%), water/cement ratio (0.35 and 0.55) and steel fiber dosage (0.5%, 1.0% and 2.0%). The experimental results included: compressive strength, direct tensile strength, splitting tensile strength, surface abrasion and drop-weight test, which were collected to carry out the analysis of variance to realize the relevancy and significance between material parameters and those mechanical properties. Test results illustrate that the splitting tensile strength, direct tensile strength, strain capacity and ability of crack-arresting increase with increasing steel fiber and silica fume dosages, as well as the optimum mixture of the fiber cementitious materials is 5% replacement silica fume and 2% fiber dosage. In addition, the Pearson correlation coefficient was conducted to evaluate the influence of the material variables and corresponds to the experiment result.

Reusing waste materials and reducing carbon emissions are crucial environmental concerns. Ground granulated basic oxygen furnace slag (GGBOS) and ground granulated blast furnace slag (GGBS) are the by-products of the steel industry and has positive effects on the environment because it reduces the problems associated waste disposal. This study reused these two products to completely replace cementitious materials, thus contributing to waste recycling, reducing the production demand for cement, and mitigating carbon emissions. Twelve mixture proportions were designed in this study, including an ordinary Portland mortar (OPM) as the control group and 11 steel/iron slag blended mortar (SISBM) experimental groups for the mechanical and cementitious characteristic experiments. The optimal mixing ratio for SISBM compressive strength ranged from GGBOS (steel slag): GGBS (iron slag) = 3:7 to 5:5 (by weight). At the age of 91 days, the compressive strength of SISBM reached 80–90% compared with that of the control group. Based on the pH values, free-CaO, and microanalysis results, the cementitious characteristics were mainly generated because the GGBOS increased the free-CaO or Ca(OH) 2 concentrations in the SISBM curing water and provided alkaline environments for Ca(OH) 2 to engage in the pozzolanic reaction with the SiO 2 and Al 2 O 3 in GGBS, forming crystals such as calcium aluminum silicate hydrate, (C–A–S–H), calcium silicate hydrate (C–S–H), and calcium–magnesium–alumina–silicate (C–M–A–S), which generated strength and strengthened microstructure.

This project is aimed to evaluate the abrasion resistance of cement-based composites which comprise polyolefin fibers and silica fume in the mixes. Material variables include water-binder ratio, dosage of silica fume and dosage of polyolefin fiber. Compressive strength, splitting tensile strength and abrasion tests were conducted and discussed. Test results indicate that the inclusion of polyolefin fiber or silica fume in cement-based composites not only increases the compressive strength and splitting tensile strength but also decreases the abrasion loss. The silica fume plays a positive rule on growth of compressive strength, splitting strength and abrasion resistance of cement-based composites due to the pozzolanic and filler effect. However, the distribution of fibers could not be controlled, resulting in a notable lack of uniformity in the specimens. The combination of silica fume and polyolefin fiber improves the strength properties and abrasion resistance than only use of polyolefin fiber. In addition, the modified Los Angeles abrasion test used in this study is suitable for the evaluation of abrasion resistance in cement-based composites. By regression analysis, the good correlations are found between compressive strength and splitting strength, abrasion ratio and compressive strength, and abrasion ratio and splitting strength.

This study presents a laboratory investigation to evaluate the natural frequency variation of the scaled-down reinforced concrete containment vessel specimen subjected to an accelerated reinforcement corrosion. The states of damage in the scaled-down specimen were assessed through measurement of the concrete resistivity, the open circuit potential, the corrosion rate and the natural frequencies. Those electrochemical parameters related with steel corrosion were extensively compared. The test results indicated that the corrosion behaviours of steel in the scaled-down specimen and the natural frequencies before and after the immersion were different. The changes in the natural frequencies were consistent with the material degradation of the concrete vessel specimen. The natural frequencies decreased with the increasing corrosion rate or the decreasing resistivities for the specimen at a higher mode, but would be a slight change for the specimen at the natural frequency of the first mode.

The main of study is to investigate the effect of moisture variation and micro-structure on the growth mold at surface of building materials. The two different water-cement ratio of mortars (w/c = 0.4, 0.6), brick and tiles were used in this study. The mercury Intrusion Porosity-Meter (MIP) was used to determine the pore distribution of building materials. The moisture variation of materials was recorded in constant climate chamber (25oC, relative humidity 80%), general indoor environment (28°C, relative humidity 55%) and water damage simulation environment. The results indicated that the pore size and distribution will affect the surface water ratio and moisture content of materials. The surface water ratio of specimen was affected by different environment seriously. The surface water ratio was an important factor in mold growth.

Sustainable development in the construction industry can be achieved by the design of multifunctional materials with good mechanical properties, durability, and reasonable environmental impacts. New functional properties, such as self-sensing, self-heating, or energy harvesting, are crucially dependent on electrical properties, which are very poor for common building materials. Therefore, various electrically conductive admixtures are used to enhance their electrical properties. Geopolymers based on waste or byproduct precursors are promising materials that can gain new functional properties by adding a reasonable amount of electrically conductive admixtures. The main aim of this paper lies in the design of multifunctional geopolymers with self-heating abilities. Designed geopolymer mortars based on blast-furnace slag activated by water glass and 6 dosages of carbon black (CB) admixture up to 2.25 wt. % were studied in terms of basic physical, mechanical, thermal, and electrical properties (DC). The self-heating ability of the designed mortars was experimentally determined at 40 and 100 V loads. The percolation threshold for self-heating was observed at 1.5 wt. % of carbon black with an increasing self-heating performance for higher CB dosages. The highest power of 26 W and the highest temperature increase of about 110 °C were observed for geopolymers with 2.25 wt. % of carbon black admixture at 100 V.

This study is aimed to evaluate the effect of sugarcane bagasse ash fineness on the properties of cement-based composites. Three sugarcane bagasse ash contents (10, 20 and 30% by weight of cement) and three particle sizes of bagasse ash (particles less than 45, 75 and 150 μm) were used as a partial replacement for cement in mortar specimens with a constant water/cementitious ratio of 0.55. The pozzolanic strength activity test, compressive strength test and scanning electron microscope observations were conducted and compared. Test results indicated that the compressive strength decreased with the addition of sugarcane bagasse ash content increased. Addition of sugarcane bagasse ash to replace cement in cementitious composites could provide hydration and pozzolanic reaction, but it would still keep more rugged and some larger pores observed from the paste surface and resulted in the weaker microstructures and poorer properties in cementitious composites. In conclusion, the critical usage of sugarcane bagasse ash is 10 % with 45μm particles.

This study is aim to evaluate the natural frequency variation of the scale-down reinforced concrete containment vessel specimen under accelerated corrosion conditions. A plastic ring was sealed around the perimeter of the cylindrical vessel bottom with the 3.5 % NaCl solution to achieve the accelerated corrosion test. Concrete resistivity, open circuit potential, corrosion rate and natural frequencies were tested and discussed in this study. Test results presented that the accelerated corrosion method with a direct 60 voltage applied was a suitable method for estimating and accelerating the concrete vessel specimen. Therefore, the changes in natural frequencies were consistent with the material degradation of the concrete vessel specimen. The natural frequencies decreased with the increasing corrosion rate or decreasing resistivities for the specimen at higher mode, but would be no change for the specimen at the natural frequency of 1stmode.

Rock wool is an inorganic fibrous substance produced by steam blasting and cooling molten glass. As with other industrial by-products, rock wool particles can be used as cementitious materials or ultra fine fillers in cement-based composites. This study investigated the microstructure of mortar specimens produced with cement-based composites that include various forms of rock wool particles. It conducted compressive strength testing, rapid chloride penetration tests, X-ray diffraction analysis, thermo-gravimetric analysis, and scanning electronic microscopy to evaluate the macro- and micro-properties of the cement-based composites. Test results indicate that inclusion of rock wool particles in composites improved compressive strength and reduced chloride ion penetration at the age of 91 days due to the reduction of calcium hydroxide content. Microscopic analysis confirms that the use of rock wool particles contributed to the formation of a denser, more compact microstructure within the hardened paste. In addition, X-ray diffraction analysis shows few changes in formation of pozzolanic reaction products and no new hydrations are formed with incorporating rock wool particles.

This study investigated the influence of individual constituents of calcined shale or hybrid constituents of calcined shale and fly ash or silica fume on the workability and compressive strength. Calcined shale is heat treated in a kiln and then ground to a finer powder and the calcination temperatures of 800 °C were used. The test results demonstrated that the workability and compressive strength decreased with the inclusion of calcined shale increased and the compressive strength of the specimens containing calcined shale all lower than that of the control specimens. It might be due to the higher water demand and lower CaO value. However, the hybrid batches with calcined shale and fly ash or silica fume enhanced better performance on compressive strength than individual constituents of calcined shale. The combination of 10 % calcined shale and 10 % silica fume in concrete seemed to give superior compressive strength and gave the highest value in the testing series. Finally, the inclusion of calcined shale is help to reduce the emissions of CO2and revealed an ecological advantage for concrete containing a binder blend of cement and calcined shale.

This study investigated the influence of crystalline sealers and curing environment on compressive strength, splitting strength and elastic modulus of cement-based composites. Four kinds of crystalline sealers addition (0 %, 3 %, 5 % and 7 %) were used in the concrete specimens. SEM observations were assisted in verifying the results of mechanical properties. The test results demonstrated that the specimens increased the mechanical properties with the inclusion of crystalline sealers increased. The crystalline sealers reacted with cement to produce the crystals and hydrations, which could fill with the pore and supply a denser microstructure. This appearance was verified by the SEM micrographs. In inclusion, the cement-based composites containing 7 % crystalline sealers seem to give superior mechanical properties, and make the pores become finer and enhance the durability.

This study employed Taguchi method to identify key factors influencing the protection provided by the surface treatment of reinforced concrete structures. We evaluated the protective characteristics of silicate concrete sealer (SCS) as well as its underlying mechanisms. An L12 (27) orthogonal array was produced using seven control factors and two levels to obtain the necessary data from only twelve experiments. Tests were performed to evaluate compressive strength, water absorption, and permeability. The major factors influencing the effectiveness of SCS included the water-binder ratio of the substrate, cumulative curing time of the sealer, content of pozzolanic material, and type of sealer materials. XRD analysis and SEM observation revealed the composition and efficacy of SCS in protecting concrete. The SCS reacted chemically with the cement hydration product Ca (OH)2 and filled the pore structure with C-S-H gel, which succeeded in greatly improving the mechanical properties of the concrete.

A low temperature process flow of preparing amorphous InGaZnO (a-IGZO) TFTs is presented. When a-IGZO TFTs are used for flexible display, they suffer the process temperature limited due to the thermal stability of plastic films. The glass transition temperature (Tg) of most usable plastic films is under 250°C. In this work, the highest process temperature was decreased to 220°C, and a-IGZO TFTs on plastic films showed excellent bias stress stability.

The present study evaluated the corrosion behavior of cement-based composites containing polyolefin fibers and supplementary cementitious materials by the impressed voltage corrosion test and the impressed current corrosion test. Material variables included the addition of polyolefin fiber (0, 0.4, 0.8 and 1.6 %), the dosage of ultrafine slag (40 and 60 %), the dosage of fumed silica (2 and 5 %) and mixed cementitious materials (35 % slag plus 5 % fumed silica and 55 % slag plus 5 % fumed silica). The test results indicate that a small amount of polyolefin fibers extends the time that a chlorine ion reaches to the surface of the rebar and decreases the corrosion rate of rebar. Nevertheless, the fiber is not very useful for the corrosion resistance of steel when the chlorine ions reach the surface of the rebar and corrode it. In addition, the inclusion of ultrafine slag or fumed silica can arrest the rebar corrosion and improve the compactness through pozzolanic reactivity and pore filling effects. According to the corrosion behavior and economy performance of the concrete structure, the combination of 55 % ultrafine slag, 5 % fumed silica and 0.8 % polyolefin fibers provides the best corrosion resistance of the tested cement-based composites.

This project was aimed to evaluate the chloride permeability and corrosion behavior of cement-based composites which comprised fibers and silica fume in the mixes. Resistivity, polarization resistance, ponding and rapid chloride penetration results of specimens were obtained through tests. Test results indicate that resistivity, open circuit potentials and direct current polarization of specimens with w/b ratio of 0.35 are higher than those of specimens with w/b ratio of 0.55. For length-diameter ratio of 65, resistivity and direct current polarization of specimens with fiber length of 35 mm were similar to those of 60 mm. In addition, the open circuit potentials of specimens with fiber length of 60 mm were slightly higher that those of 35 mm. The resistivity decreased with increasing steel fiber content, and the open circuit potential and direct current polarization increased with increasing steel fiber content. The specimens containing silica fume were found to provide higher resistivity, open circuit potentials and direct current polarization than the control specimens. The incorporation of steel fiber and silica fume in composites achieved more significantly decreases in resistivity and increases in direct current polarization than steel fiber composites or silica fume composites. The penetration depth and six-hour total charge passed of specimens for w/b ratio of 0.35 were lower than those for w/b ratio of 0.55. For length-diameter ratio of 65, the penetration depth of specimens for fiber length of 35 mm was similar to that of 60 mm. The penetration depth decreased with increased steel fiber content in the composites. By regression analysis, a good correlation between open circuit potential and direct current polarization, and chloride penetration depth and direct current polarization.

The use of rock wool waste, an industrial by-product, in cement-based composites has positive effects on the environment because it reduces the problems associated rock wool disposal. The experiments in this study tested cement-based composites using various rock wool waste contents (10, 20, 30 and 40% by weight of cement) as a partial replacement for Portland cement in mortars. The pozzolanic strength activity test, flow test, compressive strength test, dry shrinkage test, absorption test, initial surface absorption test and scanning electron microscope observations were conducted to evaluate the properties of cement-based composites. Test results demonstrate that the pozzolanic strength activity index for rock wool waste specimens is 103% after 91 days. The inclusion of rock wool waste in cement-based composites decreases its dry shrinkage and initial surface absorption, and increases its compressive strength. These improved properties are the result of the dense structure achieved by the filling effect and pozzolanic reactions of the rock wool waste. The addition of 30% and 10% rock wool wastes to cement is the optimal amount based on the results of compressive strength and initial surface absorption for a w/cm of 0.35 and 0.55, respectively. Therefore, it is feasible to utilize rock wool waste as a partial replacement of cement in cement-based composites.

The effect of penetrating sealer on the structure of surface pore, mechanical properties, and durability of cement-based composites was studied. Concrete specimens with various water/cement ratios (w/c=0.35, 0.45, 0.55) were cast and treated surfaced with various amounts of penetrating sealer at different ages. The effect of penetrating sealer on the mechanical properties of concrete was assessed by compressive strength. And, the rapid chloride permeability was also explored to test concrete durability. Test results indicate that the application of penetrating sealer significantly improves concrete compressive strength and chloride resistance. By using scanning electron microscopes observation, the penetrating depth of penetrating sealer can be determined and is about 2 cm. The penetrating sealer in this study may be categorized as deep penetrating sealer.

The study evaluates the properties of concrete mixed with inorganic silicate admixture. The admixture was used in proportions of 3%, 5%, and 7% of the weight of the cement. We performed tests on compressive strength and elastic modulus to evaluate the mechanical properties of concrete. Results show that the addition of the inorganic silicate admixture has a positive influence on the mechanical properties of concrete, with the best results obtained with 3% admixture. MIP porosity measurements determined that the addition of inorganic silicate admixture increased the density of the porous structure. SEM microscopic analysis revealed many needle-like protrusions into the porous structure of concrete. XRF chemical composition analysis indicated that these structures comprised mainly Na2O and SiO2. Can with cement hydration products Ca(OH)2 bring in Chemical reaction. Inferred pore structure Within be C-S-H gel of needle-like protruding structure. it can improve the main cause of mechanical properties of concrete.

This study is aimed to evaluate the tensile strength of cement-based composites which comprise polyolefin fibers and silica fume in the mixes. Material variables include water-cementitious ratio, dosage of silica fume, steel fiber length and dosage. Test results indicate that the compressive strength and direct tensile strength of specimens for fiber length of 25 mm are higher than that of 50 mm. The strength properties increase with increasing fiber content. Incorporation of fiber and silica fume in composites achieves significantly higher increase in compressive strength and direct tensile strength than only use of fiber or silica fume. In addition, the compressive strength, splitting tensile strength, direct tensile strength and impact resistance are fairly correlated. It contributes that the fiber content influences crack arresting ability and the silica fume influences interfacial bonding effectively.

This study is aimed to evaluate the impact performance of cement-based composites which comprise steel fibers and silica fume in the mixes. Material variables include water-cementitious ratio, dosage of silica fume, steel fiber length and dosage. Test results indicate that the impact resistance increase with increasing fiber content and water-cementitious ratio, and with decreasing silica fume content. For a given volume fraction, short fiber performs better than its long counterpart in improving the impact performance. In addition, the combination of silica fume and fibers enhances better impact behavior than individual constituents of silica fume, due to reduced the crack formation and offer the toughness of cement-based composites under impact loadings.

The studying used different metakaolin replacement ratio of cement mortar exposed to different environments to investigate the quality of cement with metakaolin basic mechanical properties of materials and white efflorescence quantify the effect of microscopic properties. The specimens were analyzed with Compressive strength test and Matlab image analysis. The results presented that: (1) Comparing with between the appropriate amount of metakaolin replacement of cement and control group, the compressive strength of the appropriate amount of metakaolin replacement of cement is higher than control group’s. Especially, the compressive strength of 15% metakaolin replacement of cement is the highest; (2) Matlab image analysis the amount found in white efflorescence into freezers > carbon tube ≒ normal atmosphere.

This study evaluates the permeability of cement-based composites, which are a mix of polyolefin fibers and silica fume. Test results indicate that permeability increases as the water/cementitious ratio increases. Silica fume in cement-based composites produced hydrated calcium silicate and filled the pores. However, permeability decreased as the addition of silica fume increased. Specimens containing polyolefin fibers also provided higher permeability resistance. The polyolefin fiber length did not have a significant effect on permeability. The decrease in the permeability is mainly due to the addition of silica fume and lower water/cementitious ratio. Addition of fibers marginally decreases the permeability. Incorporating polyolefin fiber and silica fume in composites achieved more significant decreases in permeability. The correlated test results reveal the interrelationship between them.

This study evaluated the mechanical properties of cement-based composites produced with added polyolefin fibers and silica fume. Material variables included the water-cementitious ratio, the dosage of silica fume, and the length and dosage of polyolefin fiber. Researchers conducted tests on compressive strength, splitting tensile strength, direct tensile strength, resistivity, rapid chloride penetration, and initial surface absorption, and performed microscopic observation. Test results indicate that the specimens containing silica fume have higher compressive strength than the control and specimen made with fibers. The specimens with polyolefin fiber and silica fume have considerably higher tensile strength and ductility than the control and specimens made with silica fume. The specimens containing silica fume and polyolefin fiber demonstrated better resistance to chloride penetration than composites with polyolefin fiber or silica fume. For a given volume fraction, short polyolefin fiber performs better than its long counterpart in improving the properties of concrete. Specimens containing silica fume demonstrated a significant increase in resistivity and decrease in the total charge passed and absorption. Scanning electron microscopy illustrates that the polyolefin fiber acts to arrest the propagation of internal cracks.

The present study aimed to establish the durability indices of cement-based composites containing supplementary cementitious materials. The influences of compressive strength, permeability, and microstructure of cement-based composites containing fly ash and silica fume were discussed. The relationship between pore structure and corrosion behavior was investigated and compared. The results demonstrate that the addition of silica fume in cement-based composites resulted in a higher compressive strength, a lower absorption, a lower critical pore size, a lower chloride diffusion coefficient, and a lower corrosion rate. The composites containing 10% silica fumes performed better in permeability than composites containing 5% silica fumes, because silica fumes can narrow down the size of large capillary pores and densify the pore structure. The addition of fly ash in composites also enhanced the compressive strength and the permeability but was not as effective as silica fume. Unhydrated fly ash grains caused a looser pore structure and reduced the permeability. The combination of fly ash and silica fume enhanced the compressive strength and the permeability and specimens containing 5% silica fume and 10% fly ash had increased more in compressive strength and decreased more in permeability than specimens containing 5% silica fume or 15% fly ash. Moreover, the corrosion rate, the chloride diffusion coefficient, and the critical pore size were suitable for evaluating the durability of cement-based composites. A regression analysis found that the probability of rebar corrosion was greater than 90%, when the corrosion rate was 11.54 μm/yr, the chloride diffusion coefficient was 0.62 × 10 −12 m 2 /s, or the critical pore size was 26.71 nm.

Leaching is one of the major factors that alter the mechanical properties of cement-based composites. This study is aimed to investigate the effect of leaching on the properties of cement-based composites. Specimens with two water/cementitious ratios and two mineral admixtures were tested. An electrical potential was applied to accelerate the leaching process. Compressive strength test, scanning electronic microscopy, thermogravimetric analysis and X-ray diffraction analysis were conducted. Test results demonstrated that the calcium leaching reduced compressive strengths of concrete specimens, and such effect was prominent on the specimens without mineral admixtures. The leaching resistance increased with a decrease in water/cementitious ratio and an increase in amount of mineral admixtures. The mineral admixtures would reduce the amount of calcium hydroxide and refine the pore structure through pozzolanic reactions. A fair relationship was found between the calcium leaching and the compressive strength.

This paper presents an experimental investigation on the effect of incinerator bottom ash (IBA) fineness and the cooled process of molten IBA on fresh mortar properties and compressive strength of hardened mortars. IBA with two finenesses, an original IBA, and a pulverizing incinerator bottom ash (PIBA) powder, with maximum particle size of 4.75 and 0.074 mm respectively were used to partially replace sand and Portland cement at 0%, 10%, 20%, 30%, and 40% by weight. The pozzolanic activity characteristics of powder were obtained from melting the above PIBA in an electric-furnace at 1450 °C for 1 h. and chilled by quenching in water (WIBA) and air (AIBA). Results indicate that incinerator bottom ash caused a reduction in compressive strength, unit weight, and flowability values when used as a replacement for sand and cement. However, IBA can be processed by melting to regain reactive pozzolanic activity, which may be used to partially replace cement.

This study investigates the properties of cement-based composites with addition of various rock wool wastes. The rock wool wastes are an insulating material. This study used rock wool waste with a cylindrical size distribution ranging from 17 to 250 μm, 30% of which is less than 150 μm. Rock wool waste can be used as a suitable substitute for coarse and fine aggregates, saving on the cost of natural aggregates and minimizing the environmental impact of solid waste disposal. In addition, because the composition of rock wool waste is similar to other pozzolan materials such as fly ash, ground granulated blast-furnace slag (GGBS), and silica fume, it can be considered as a supplementary cementitious material. Experimental results show that partially replacing natural aggregates with rock wool wastes improves the compressive strength, splitting tensile strength, abrasion resistance, absorption, resistance to potential alkali reactivity, resistivity, and chloride-ion penetration of cement-based composites. These improved properties are the result of the dense structure achieved by the filling effect of pozzolanic product. Pozzolanic strength activity index (PSAI) results and scanning electron microscope (SEM) observations confirm these findings. Therefore, rock wool wastes can act as either a cementitious material or inert filler in cement-based composites, depending on the particle size. The critical size appears to be 75 μm.

In this study, the pore systems of cement‐based composites were investigated using absorption, rapid chloride penetration, rapid migration, ponding, mercury intrusion porosimetry (MIP), and scanning electronic microscopy (SEM). Direct current polarization resistance and other permeability parameters were used as indices to justify the effects of fiber and silica fume addition on the permeability of cover concrete. Cement‐based composites containing 10% silica fumes were found to have higher compressive strength, lower absorption, lower coefficient of chloride ion diffusion, lower penetration of chloride ions and higher polarization resistance than those of control specimens. Composites with a combined addition of fiber and silica fume further increased polarization resistance and compressive strength. Addition of silica fumes further improves the permeability of fiber cement composites due to the positive effect from pozzolanic reaction, which produces denser and more homogeneous structures in th...