Relationships between Modified Methylene Blue Value of Microfines in Manufactured Sand and Concrete Properties

To better understand and assess the effect of microfines on concrete properties, the synergetic effect of methylene blue value and content of microfines on properties of low and high strength concrete was studied and then the relationships between the index of modified methylene blue value （MMBV） and concrete properties were investigated. The results show that relationships between MMBV and fresh and hardened properties of concrete can be fully established, and the correlation between MMBV and C60 concrete property is higher than the correlation between MMBV and C30 concrete. With the increase of MMBV, concrete workability and frost resistance decrease while drying shrinkage decreases; however, compressive strength and chloride-ion penetration resistance of C30 concrete have not been negatively affected whereas those of C60 concrete are significantly deteriorated when MMBV exceeds 100. To make use of microfines without remarkably damaging concrete quality, it is suggested that MMBV of microfines in MS used in C30 and C60 concrete be no more than 100.

Mechanical Properties of Sea Water Sea Sand Coral Concrete Modified with Different Cement and Fiber Types

The mechanical properties of modified sea water sea sand coral concrete(SWSSCC)under axial compression were experimentally studied.Two different parameters were considered in this test:types of cement and fiber.An experimental campaign was developed involving uniaxial compression tests and the use of digital image correlation(DIC)method to analyze the strain distribution and crack propagation of specimen.Test results indicated that the compressive strength and elastic modulus of SWSSCC were improved by adding stainless steel fibers(SSF),while polypropylene fibers(PF)enhanced the SWSSCC peak deformation.It was found that the elastic modulus and strength of SWSSCC using ordinary Portland cement(OPC)were higher compared to specimen with low alkalinity sulphoaluminate cement(LAS).Typical strain distribution changed with the variation of fiber types.The propagation and characteristics of cracks in SWSSCC containing PF were similar to those of cracks in SWSSCC.However,the propagation of cracks and the development of plastic deformation in SWSSCC were effectively hindered by adopting SSF.Finally,an analytical stress-strain expression of specimen considering the influences of fibers was established.The obtained results would provide a basis for the application of SWSSCC.

Polymer-modified Concrete with Improved Flexural Toughness and Mechanism Analysis

By selecting different types of polymer mixing into concrete, the toughness of concrete is investigated, and results indicate polymer has obvious effect to improve the toughness of concrete. Microstructure of polymer-modified concrete were studied through environment scanning electron microscope and digital micro-hardness tester, results show that polymer acts as a flexible filler and reinforcement in concrete, and alters the microstructure at mortar and ITZ. By crack path prediction and energy consumption analysis, the crack path of polymer-modified concrete is more tortuous and consumes more energy than that of ordinary concrete.

Anti-cracking Property of EVA-modified Polypropylene Fiber-reinforced Concrete Under Thermal-cooling Cycling Curing

In order to investigate the synergistic effect of re-dispersible powder-ethylene-vinyl acetate copolymer(EVA) and polypropylene fiber on the crack resistance of concrete under thermal fatigue loading, the compressive strength, ultimate tensile strength, ultimate tensile strain and tensile modulus of elasticity were tested. In addition, ultrasonic method and scanning electron microscope analysis were used to explain the microstructure mechanism. The results show that polypropylene fiberreinforced concrete presents a better performance on crack resistance than ordinary concrete, and the synergism of EVA and polypropylene fiber can improve the anti-cracking ability of concrete further.

Experimental Study of Rubberized Asphalt Emulsion Modified Portland cement concrete

The poor fatigue properties and high rigidity of cement asphalt emulsion treated mis(CETM) have for a long time been problems restricting its further development making it impossible for C-ETMto be used as surface layer materials. In this paper, a new kind of cement asphalt emulsion composite-rubberized asphalt emulsion modified Portland cement concrete (RACC) was proposed, which was formed by dispersing rubberized aSPhalt emulsion coated coarse aggregates into cement mortar matrix. In order to evaluate systematically the performance of RACC, laboratory tests with nearly one thousand SPecimen were conducted for resilient modulus, fatigue properties, ultimate ban and length,abrasion, temperature contraction, and dry shrinkage. The experimental results show that the problems existed in C-ETM have to a great extends been solved by RACc. To verify the field performance and inquire into paving technology, teSt road appearsatlsfactory it is concluded that when thed ape surface laycr of semi-rigid base course, RACC is more for surface layer material than both Portland cement concrete(PCC) and asphalt concrete(AC)

Polymer Modified Concrete of Blended Cement and Natural Latex Copolymer: Static and Dynamic Analysis

This paper deals with the effect of blended cement and natural latex copolymer to static and dynamic properties of polymer modified concrete. The polymer was used copolymer of natural latex methacrylate (KOLAM) and copolymer of natural latex styrene (KOLAS) with composition of 1%, 5%, and 10% w/w of weight of blended cement in concrete mixture. They are tested for compressive strength, flexural strength, splitting tensile strength, and modulus elasticity for static analysis, and impact load and energy dissipation profile for dynamic analysis. The result shows that KOLAM with concentration 1% give better performance in static and dynamic properties. The KOLAM 1% gives improvement in flexural strength, splitting tensile strength and modulus elasticity about 4%, 13% and 3% compared to normal concrete. And for dynamic properties, KOLAM 1% could reduce impact load up to 35% and improve energy dissipation capacity about 45% compared to normal concrete. The concentration of KOLAM higher than 1% resulting negative effect to static and dynamic properties, except modulus of elasticity. For KOLAS, there were no positive trends of static and dynamic properties.

Laboratory Evaluation of the Stiffness Modulus of a Modified Bituminous Concrete with PR PLAST Sahara

Uneven roads surface can be observed on bituminous pavements. This is due to moving loads and climate conditions. If the observed deformations exceed the elastic limit, important damages can occur, so new materials are used to improve the stiffness modulus of bituminous mixtures. To achieve this, a modified bituminous concrete by addition of the PR PLAST Sahara （produced by PR industries and PLAST for Plastic） mainly used in arid region has been studied. The use of this additive at various percentages 0.1, 0.3, 0.6 and 0.9 by weight of bituminous concrete has been investigated to determine its stiffness modulus. An experimental design using the Taguchi tables has been elaborated to reduce the number of tests. Marshall and NAT （Nottingham asphalt tester） tests have been carried out, and a mathematical model of the stiffness modulus has been proposed.

Modified Concrete Using Polyethylene Terephthalate Plastic Waste as a Partial Replacement for Coarse Aggregate

The present work evaluated the properties of modified concrete using polyethylene terephthalate (PET) bottle waste as a partial replacement for coarse aggregate. Modified concrete samples were designed using a water/cement (W/C) ratio of 0.50 and varying percentages of PET replacement (3%, 7%, 10%, and 15% by volume). Dreux Gorisse’s formulation approach was used to make the final products, and the mechanical properties of the samples were determined using Controlab presses. This modified concrete with PET chips has shown that with a 10% replacement of PET chips, the fresh density decreases by 3.56%, and the hardened state density decreases by 2.01%. The water absorption and thermal conductivity of the formulated concretes decreased. However, the results showed that the slump of these fresh concretes increased as the percentage of plastic aggregate replacement increased. Based on the results, incorporating PET aggregates into concrete contributes to good workability, and lightweight concrete structures, and provides some thermal comfort in concrete structures.

Toughness of Polymer Modified Steel Fiber Reinforced Concrete

An experimental investigation is carried out to study the toughness of polymer modified steel fiber reinforced concrete. Volume fraction of steel fibers is varied from 0% to 7% at the interval of 1% by weight of cement. 15% SBR latex polymer was used by weight of cement. Cubes of size 150 × 150 × 150 mm for compressive strength, prism specimens of size 150 mm × 150 mm × 700 mm for flexure strength and, specimen of size 150 × 150 × 150 mm with 16 mm diameter tor steel bar of length 650 mm embedded in concrete cube at the center for bond test were prepared. Various specimens were tested after 28 days of curing. Area under curve (toughness) is measured and mentioned in this work.

Effects of an AMPS-modified Polyacrylic Acid Superplasticizer on the Performance of Concrete Materials

A self-made 2-acrylamide-2-methyl propylene sulfonic （AMPS）-modified polyacrylic acid superplasticizer and two other commercially available superplasticizers with different molecular structures are used in this study to investigate the effect of an AMPS-modified polyacrylic acid superplasticizer on the properties of concrete materials. In the experiments, initial and 1.5 h slumps over time after admixtion are determined by adding different dosages of three superplasticizers into the premixed concrete to characterize the slump loss resistance of the premixed concrete. The water-reducing rates of three different types of concrete are determined to characterize the water-reducing capacity of the concrete with each superplasticizer. The 3, 7 and 28 d compressive strength is determined to characterize the mechanical properties of the concrete with each superplasticizer. In the meanwhile, 1, 1.5 and 2.0 h slump loss rates over time after admixtion are determined by adding different dosages of the three superplasticizers into the high-performance concrete （HPC） to characterize the slump loss resistance of HPC. The 7, 28, 60 and 90 d compressive strength is determined to characterize the compressive properties of HPC with each superplasticizer. The dry shrinkage rates of three different types of HPC are determined with each superplasticizer. Electric flux after standard curing for 56 d and chloride ion diffusion coefficient after curing for 28 d of I-IPC are determined to characterize the impermeability of HPC with each superplasticizer. The cross-section was examined using a scanning electron microscopy （SEM） system. Results demonstrate that the AMPS-modified polyacrylic acid superplasticizer has better water-reducing effect and slump than the two commercially available polyacrylie acid superplasticizers. The AMPS-modified polyacrylic acid superplasticizer also shows significant improvement of the compressive strength, especially in comprehensive performance of HPC. In conclusion, the AMPS-modified polyacrylic acid superplastieizer is particularly suitable for the preparation of HPC.

Influence of Nano-Materials on Mechanical and Permeation Characteristics of High Strength Concrete

Efforts have been made to evaluate the influences of the addition of nanoparticles on the strength,durability and mineralogical changes of high strength concrete(HSC).Therefore,mixes were prepared for conventional concrete mix(CCM)of M80 grade.Further,various mixes were prepared by replacing cementitious materials initially with 1%Nano-CaCO_(3)(NC),2%NC,3%NC in the CCM,and then 1%NC and Nano-SiO_(2)(NS)NS,2%NC and NS,3%NC and NS(NC and NS were in equal proportion)in the CCM.The developed concretes were then evaluated for mechanical properties,permeation characteristics,and mineralogical studies.From the studies,it is found that the concrete at 2%NCS possesses superior mechanical and superior permeation characteristics of all the mixes.A clear variation in the mineralogical structure with the addition of nanoparticles has been observed.

Sensitive Voltammetric Determination of Captopril Using a Carbon Paste Electrode Modified with Nano-TiO_2/Ferrocene Carboxylic Acid

A carbon paste electrode (CPE) modified with ferrocene carboxylic acid (FcCA) and TiO2 nanoparticles was constructed by incorporating TiO2 nanoparticles and ferrocene carboxylic acid into the carbon paste matrix. The electrochemical behavior of captopril (CAP) at the surface of the modified electrode was investigated using electroanalytical methods. The modified electrode showed excellent electrocatalytic activity for the oxidation of CAP in aqueous solutions at physiological pH values. Cyclic voltammetric curves showed that the oxidation of CAP at the surface of the modified electrode reduced its overpotential by more than 290 mV. The modified electrode was used for detecting captopril using cyclic voltammetry and square wave voltammetry techniques. A calibration curve in the range of 0.03 to 2400 μmol/L was obtained that had a detection limit of 0.0096 μmol/L (3?) under the optimized conditions. The modified electrode was successfully used for the determination of captopril in pharmaceutical and biological samples.

Preparation of Nano-SiO_2/Amino-modified Polysiloxane Hybrid Superhydrophobic Coating and Thermal-stability Characterization

We put forward a large-area and cost-effective method to fabricate superhydrophobic coating by introducing in-situ functionalized nano-SiO2 into side-amino modified hydroxy-terminated polydimethylsiloxane （SA-HTPDMS） curing system. With the characterization using water contact angle （WCA） tester, Fourier transform infrared spectroscopy （FTIR）, scanning electron microscope （SEM）, atomic force microscopy （AFM） and simultaneous thermal analysis, the as-prepared coating displayed a tremendous WCA of 154.8±1°, sliding angle （SA） about 3.5° and stable self-cleaning property range from -10 to 80 ℃. It was also found that the synergistic effect of surface micro-nano hierarchical structure and chemical hydrophobicity, stability from matrix had made contributions to the superhydrophobicity and excellent heat resistance up to 300 ℃.

Properties of Chemically Synthesized Nano-geopolymer Cement based Self-Compacting Geopolymer Concrete(SCGC)

The physical and mechanical properties of self-compacting geopolymer concrete(SCGC) using chemically synthesized nano-geopolymer cement was investigated. Nano-geopolymer cement was synthesized using nano-silica, alkali activator, and sodium aluminate in the laboratory. Subsequently, nine nanogeopolymer cement sbased SCGC mixes with varying nano-geopolymer cement content, alkali activator content, coarse aggregate(CA) content, and curing temperature were produced. The workability-related fresh properties were assessed through slump flow diameter and slump flow rate measurements. Mechanical performances were evaluated through compressive strength, splitting tensile strength, and modulus of elasticity measurements. In addition, rapid chloride penetration test, water absorption, and porosity tests were also performed. It was assessed that all mix design parameters influenced the fresh and hardened properties of SCGC mixes. Based on test results, it was deduced that nano-geopolymer cement SCGC performed fairly well. All the SCGC mixes achieved the 28-day compressive strength in the range of 60-80 MPa. Additionally, all mixes attained 60% of their 28-day strength during the first three days of elevated temperature curing. FTIR and SEM analyses were performed to evaluate the degree of polymerization and the microstructure respectively for SCGC mixes.

Synthesis of a Green Nano-Silica Material Using Beneficiated Waste Dunites and Its Application in Concrete

Nano-silica, one of the substances boosting the field of nanomaterials, can be produced by dissolving olivine in acid. The dissolution of olivine is a convenient alternative route to the existing methods of nano-silica production (neutralization of sodium silicate and flame hydrolysis) because the olivine dissolution is a low temperature process making this method cheaper and greener. Furthermore, this process can use waste olivine materials for the production of nano-silica. The produced nano-silica has a specific surface area between 100 and 400 m2/g;a primary particle size between 10 and 25 nm, which is agglomerated in clusters;and an impurity content below 5 wt.%. In addition, olivine nano-silica can be classified as a pozzolanic material with an activity index of 101%. The optimum replacement level of olivine nano-silica in conventional vibrated concrete is around 5% by volume resulting in: 1) a compressive strength increase of 20%;2) a CO2 emission reduction of 3%. Therefore, the use of the olivine nano-silica in CVC does not only improve the compressive strength but also reduce the CO2 emissions.

Nano-treatment of Autoclaved Aerated Concrete Waste and Its Usage in Cleaner Building Materials

Autoclaved aerated concrete waste(AACW)was used as a raw material to prepare nucleation seed for acceleration of Portland cement.Nano AACW seed with median particle size of 324 nm was prepared by wet grinding method.Both the electrical conductivity and pH value of nano AACW suspension were obviously improved.Both the setting times and intensity of the main hydration heat peak were promoted by nano AACW,indicating the possibility of AACW suspension as nucleation seed.The early age compressive strength before 3 days was also clearly improved by nano AACW,with no negative effect on the late age strength.Furthermore,the reduced CH content with dosage of nano AACW indicates that nano AACW not only plays a role of nucleation seed in cement hydration,but also has a certain pozzolanic reaction.

Research Progress of the Modification in Sulfur Concrete

Sulfur concrete (SC) is a relatively new type of construction material with advantages of the strong corrosion resistance and quick setting and hardening, which has been applied in construction engineering. SC is brittle with large hardening shrinkage, so it needs to be modified in the process of use. How SC can be modified is a key point of its improvement. In view of the existing research results, the research status of the modification in SC is summarized and concluded in this paper to generate some insights, including the understanding of variations in temperature, effects of molding methods and the addition of fillers and modifiers.

Effect of Hot Environment on Strength and Heat Transfer Coefficient of Nano-Clay Concrete Paper Title

This study selected water-cement ratio 0.5 and slump 16 cm for ACI mix design, and used nano- clay to replace 0.1%, 0.3% and 0.5% of cement by weight to make cylinder and angle column specimens. The effects of different high temperatures on the compressive strength and heat transfer coefficient were tested, and the ignition loss of nano-clay cement paste was measured. The results showed that an appropriate replacement of nano-clay for 0.3% - 0.5% of cement can enhance the strength and heat transfer coefficient of concrete, especially 0.3% replacement. The 0.1% nano- clay replacement for cement reduces the strength and heat transfer coefficient of concrete. When the ambient temperature exceeds 300?C, the nano-clay concrete strength begins to decline, and the heat transfer coefficient decreases greatly, the effect of hot environment on the strength trend of nano-clay concrete is similar to that on normal concrete. When the nano-clay replaces cement by 0% - 0.5%, the ignition loss is approximately in exponential and logarithmic relationships to the compressive strength respectively when the ignition loss is smaller than and greater than 6%.

Preparation of Nano-Modified Polyacrylamide and Its Application on Solid-Liquid Separation in Waste Drilling Mud

To satisfy the requirement on solid-liquid separation in high-density waste drilling mud, prepare the nano-modified polyacrylamide(PAM) flocculant for high density waste drilling mud by in-situ dispersion method, direct dispersion method and simultaneous formation method. The result showed the flocculent effect of nano-modified polyacrylamide prepared by simultaneous formation method was the best. When the content of water glass and acrylamide(AM) were respectively 3% and 15% , reaction temperature was 60?C and reaction time was 3h, the performance of product was the best. The water content in filter cake was 24.32% after the waste drilling mud disposed by the optimization flocculant. The flocculent effect of optimization flocculant was superior to that of other flocculant in market.