Polymer-modified Cement Research Articles

The Effect of Fe2O3 on the Mechanical Properties of the Polymer Modified Cement Containing Fly Ash

Composite materials containing industrial wastes and polymer additions are modern materials possessing new properties. This paper is devoted to determination of properties of a cement-based composite material. The comparison of mechanical properties of a polymer modified Portland cement stone with fly ash and micro-sized Fe2O3 is considered. On the basis of the analysis of the research results it is shown that it is more preferable to use the polymer powder for modifying of Portland cement with 15% of the fly ash replacement and the optimal quantity of Fe2O3 is 0,01% by weigth of cement.

Accelerated curing regimes for polymer-modified cement

Polymer-modified materials provide numerable enhancements to cementitious composites. However, the curing/hardening conditions for cementitious and polymeric materials differ significantly, although they are mixed to form a single entity. Cement requires a moist environment for the hydration process to occur, while polymers require a hot and dry environment. Consequently, the polymer-modified composite exhibits lower compressive strength than the ordinary cementitious product. The objective of the present study was to resolve this issue by using accelerated curing regimens, following the fundamental concept that the dominant contribution to the toughness of the composite matrix is from the cement system, while polymer films refine the microstructure. Hygrothermal treatment for plain mortar was first developed in order to achieve 100% of the 28-day strength after treatment is completed. The hot + dry treatment required for the formation of polymer film was studied in the second phase of this study, together with an investigation of the microstructure using scanning electron microscopy. The results show that, after being subjected to the hygrothermal and hot + dry treatment, polymer-modified mortar can achieve low intrinsic permeability without compromising the compressive strength. A 15% polymer loading in styrene–butadiene rubber- and epoxy-modified mortar led to 46% and 18% higher compressive strengths, and 660% and 460% lower intrinsic permeabilities, compared with unmodified mortar, respectively.

Study on Crack Bridging Ability of Polymer-Modified Cement Based Compounds for Waterproofing Material

China's existing polymer-modified cement based compounds for waterproofing material standards are used for the tensile strength test and elongation at break test as the test method to evaluate the performance of the product extension. The elongation only reflects the extension ability of product, but cannot indicate the crack bridging ability of the product. In engineering applications, there is a requirement for higher bridging cracks ability of the products. In this paper, 9 samples of polymer-modified cement based compounds for waterproofing material were tested. Crack bridging ability was tested under the standards and methods in DIN EN 14891:2013-07. Tensile strength and elongation at break were tested according to the standards and methods in GB23445:2009. The crack bridging ability test results are between 0 to 2.08mm, in which 5 of them meet the requirements of greater than 0.75mm according to DIN EN14891:2013-07.The tensile strength test results are between 1.13MPa to 3.19MPa, the elongation at break test results are between 4% to 350%.The results show that higher tensile strength and higher elongation at break will have good ability of crack bridging. Samples with better crack bridging ability are close to type III product according to GB23445-2009 which requires tensile strength ≥ 1.8MPa and elongation at break ≥ 30%. Crack bridging ability directly reflects the product’s ability of crack bridging, and is more in line with the actual requirements in engineering applications. It is recommended that the crack bridging ability test method should be adopted in the formulation of China polymer-modified cement compounds for waterproofing material standards.

Early hydration-retarding mechanism of polymer-modified cement

Polymers added to cement to enhance its physical properties can retard its hydration reaction and actually reduce its compressive strength. The mechanism of this retardation in cement composites containing ethylene–vinyl acetate was, therefore, investigated by evaluating the viscosity, heat of hydration, setting time and Ca2+ ion leaching with various ratios of polymer to cement. It is found that increasing the amount of polymer caused a decrease in Ca2+ ion leaching owing to an increase in viscosity, and that this delayed hydration. Furthermore, the hydration process hydrolysed the vinyl acetate in ethylene–vinyl acetate, producing acetate ions that react with Ca2+ to form calcium acetate. As this reaction consumed Ca2+ ions, it created unreacted sulphate ions that further delayed the hydration reaction. It is these two factors that are considered to be the main cause for the delayed hydration reaction observed in cement–polymer composites.

The Properties of Polymer-Modified Mortars Using Pozzolana Active Admixtures

The paper focuses on the changes in properties of cement and polymer-modified cement mortars when pozzolana-active admixture are added into the mixture. Natural and artificial pozzolans based on amorphous and mineral silicon dioxide were used. In order to explain the results obtained from the experiment and to gain new insights about the microstructure of the mixtures, equipment such as SEM sampling, RDA analysis, DTA and high-pressure mercury intrusion porosimetry were used.

Investigation on the relationship between flexural strength, flexural toughness and impact toughness of styrene–butadiene rubber latex-modified cement concrete

The flexural strength, flexural toughness and impact toughness of styrene–butadiene rubber latex-modified cement concrete are studied in this study. In order to reveal the mechanism, the microstructure and pore size distribution are researched by means of scanning electron microscope and mercury intrusion porosimetry. The results show that the flexural strength, flexural toughness and impact toughness all first increase and then decrease when polymer–cement ratio increases from 0 to 60%, but the optimum value of corresponding polymer–cement ratio is different. The flexural toughness and impact toughness have no significant relations to the flexural strength, but there are roughly linear relationships between the flexural toughness and impact toughness. Scanning electron microscope and mercury intrusion porosimetry show that the proper addition of polymer can make the concrete denser, the deviation of flexural toughness and impact toughness decrease, but the flexural toughness is lower, and it can characterise the toughness of polymer-modified cement concrete with more accuracy.

Influence of Coagulation of Polymer Dispersion on the Properties of Polymer-Modified Mortar

The coagulation process of polymer dispersion in cement-based materials is different from that of the pure polymer dispersion during drying and film formation. This process is influenced by the various ions released from cement hydration and the interaction between polymer and cement grain in the water. This paper focuses on the coagulation of polymer dispersion during cement hydrating and the influence on the performances e.g. water absorption, flexural and compressive strength and bonding strength of cement mortar. Commercial anionic styrene-acrylate polymer dispersion was investigated in the coagulation process in the polymer-modified cement paste with polymer to cement ratio (p/c) from 5% to 20% and water to cement ratio of 0.3. The amount of coagulated polymer particles was measured by testing the solid content of the supernatant of the diluted polymer-modified cement paste for a period of time. The calorimetric property was measured by TAM AIR calorimeter. Water absorption and mechanical properties of the modified mortar were also measured according to the China standard. The result showed that the polymer dispersion mixing with cement was found to be coagulated in the very early stage under the low polymer to cement ratio, and the quantity of the polymer particles remained in the liquid is quite low within few minutes during this fast coagulation process. The fast coagulation process undermines the influence of polymer dispersion on the cement hydration and the heat evolution. But it has negative impact on the mechanical properties and water resistance. Adding of surfactant into the polymer dispersion extends the coagulation process and improves these performances.

Study on waterproof mechanism of polymer-modified cement mortar

In order to clarify the effect and influence mechanism of polymers on the waterproof performance of cement mortar, the effects of three polymers on capillary water absorption, impermeability, porosity and cracking of cement mortar were studied. The correlation between porosity and waterproof performance was analysed and the waterproofing mechanism of polymer-modified mortar was explored. The results show that waterproof performance, characterised by capillary water absorption and impermeability, was significantly improved by all three polymers but to different extents. The cracking weighted value declined and open porosity decreased with an increase in polymer dosage. The penetration depth of water into mortar and the capillary water absorption showed linear and exponential growth, respectively, with an increase in open porosity. The polymers were found to improve pore structure and refine porosity of >50 nm and thus weaken the negative effect of porosity on the waterproof performance of mortar.

Determination of Compressive Strength of Cement and Polymer-Modified Cement Pastes with Pozzolans

The article focuses on the use of tree types of pozzolanic materials in the production of cement pastes and polymer-modified cement pastes. The determined physical-mechanical parameters of the pastes with pozzolanic materials were compared with a pure cement paste. For polymeric modification, ethylene/vinyl acetate copolymer (EVA) was used, which was added to the mortar and concrete during the preparation to improve some properties such as fracture toughness, impermeability and bond strength to various substrates.

Physical and rheological properties of acrylate–styrene–acrylonitrile modified asphalt cement

Polymer-modified asphalt cement (PMAC) has been used in the last few decades to mitigate several root causes of asphalt-cement failures. Furthermore, it has been proved that polymers used as asphalt-cement modifiers had significant influence on the properties of asphalt at low and high temperatures. The primary objective of this study was to investigate the rheological, mechanical, and physical properties of acrylate–styrene–acrylonitrile (ASA) PMAC. Three types of samples with different concentration of the additives were studied, namely asphalt cement with 3%, 5%, and 7% of ASA. The influence of the modifier on the rheological, mechanical, and physical properties was evaluated by conventional tests (penetration, softening point, and ductility), viscosity, X-ray diffraction (XRD), and measurements from a dynamic shear rheometer (DSR). From the results of this study, it is evident that the addition of ASA has a significant effect on the rheological properties of asphalt cement. The temperature susceptibility of modified asphalt cement (MAC) was reduced compared with unmodified asphalt cement. In addition, the storage-stability test confirmed that the ASA–MAC has good compatibility. Furthermore, XRD results revealed that the phase of ASA–MAC changed from amorphous to semi-crystalline, which indicates that these materials have good workability. Based on the results from the DSR measurements, ASA–MAC has reduced temperature susceptibility, and increased stiffness and elastic behavior in comparison to unmodified asphalt cement. Moreover, ASA–MAC shows improved rutting resistance at high temperatures and higher fatigue performance at low temperatures. As a result, ASA can be considered as a proper alternative additive to modify the properties of asphalt cement.

Performance of porous European mix (PEM) pavements added with crumb rubbers in dry process

Crumb rubber modifier, made from scrap tires, has been introduced into the production of different types of hot mix asphalt in either wet or dry process. To determine if the rubberised asphalt mix performs as well as polymer-modified asphalt cement (PMAC), test sections of rubberised and control PMAC porous European mix (PEM) in Georgia were examined through a visual inspection and laboratory testing. The results indicated that the performance of rubberised PEM pavements from visual inspection was almost equal to that of PMAC PEM (as the controls) with no rutting or cracking being found, except that the Cantabro test showed a higher mass loss after 3 years' service. After 5 years' service in I-75 Perry, the rubberised PEM still performed a little better rutting resistance, although the rubberised section experienced about twice cumulative traffic as compared to the control; the other visual inspections remained the same.

Mechanism and Durability of Repair Systems in Polymer-Modified Cement Mortars

This paper investigated the mechanism and durability of repair systems made of ordinary cement-based repair mortar and three kinds of polymer-modified repair mortars with old concrete, SBR dispersion, SAE dispersion, and SAE powder. By comparing the bonding properties of mortars before and after erosion, it was found that polymers could effectively improve the durability of the repair system and SAE powder had the best improvement. Micromorphology study of the repair mortar and the interface of repair mortar with old concrete through SEM showed that the polymer film formed from SAE powder whatever in the mortar or at the interface was dense and tough, the film formed from SAE dispersion was loose and weak, while the film formed from SBR dispersion was in between them, which explained the difference in the tensile bond strength and the durability of the repair systems.

Effect of Corrosion Inhibitor on the Compressive Strength of Polymer-Modified Cement Mortars

This study examined initial flow and compressive strength development of polymer-modified cement mortar according to the addition of corrosion inhibitor. Test results showed that with the increase of the amount of corrosion inhibitor, the initial flow of mortars increased whereas compressive strength decreased. The strength development of mortar specimens could be reasonably predicted using the modified ACI 209 equations.

Improvement of reinforced concrete properties based on modified starch/polybutadiene nanocomposites

A novel polymer-modified cement concrete with carboxymethyl starch (CMS) and 1,4-cis polybutadiene (PBD) system by mixing polymer dispersions or redispersible polymer powders with the fresh mixture have been examined. In this paper, the addition of CMS-PBD powders in an aqueous solution is studied. Polymeric molecules are supplied on a molecular scale, improving the approach of the relatively large cement grains by the polymers. The chemical and mechanical properties of CMS-PBD-modified cement concrete have been studied. The additions of very small amounts of CMS-PBD polymeric system results in an improvement of the durability and the adhesion strength of the cementitious materials, which makes them appropriate as repair materials.

Anisotropy in compressive strength and elastic stiffness of normal and polymer-modified asphalts

Anisotropy in the compressive strength and the elastic stiffness of normal hot-mix asphalt (HMA) and polymer-modified asphalt (PMA) were investigated experimentally. Two types of prismatic specimen with planes of compaction either normal to or parallel to the applied axial compression were used. Both axial and lateral principal strains were measured locally. Continuous monotonic loadings at a constant strain rate were axially applied to investigate the anisotropy in the compressive strength. Very small strain–amplitude cyclic stresses were also applied by means of another load-controlled apparatus to investigate the anisotropy in the elastic stiffness. The followings were found: (i) compressive strengths of both HMA and PMA are anisotropic in that the values for the vertical direction were significantly larger than those of horizontal direction; (ii) the small strain stiffness of both HMA and PMA are anisotropic with the vertical elastic Young׳s modulus being greater than the horizontal elastic Young׳s modulus; (iii) the elastic Young׳s modulus is stress level dependent, exhibiting a hypo-elastic behaviour; and (iv) the elastic Young׳s modulus becomes greater with the applications of the normal and the polymer-modified asphalt cement binders.

Study on Modification Mechanism of the Polymer Modified Cement Concrete

The Modification mechanism of the Polymer Modified Cement Concrete was studied by the DTA,SEM and MIP with the confirmation of lab test results. The research indicated: the more dosage of the polymer, the less content of the Ca(OH)2 in the Cement hydrated product. The pore structure was improved evidently simultaneously. The polymer film tend to more complete and interweaved with Hydration products. Therefore the netted structure was formed and the flexiblity of concrete was increase greatly. Lab test results also proved it：when continued adding the polymer, the performance of concrete improved remarkably.

Mechanical Property Performance of Polymer-Modified Calcium Sulfoaluminate Cement Mortar Systems

Abstract The purpose of this study was to assess the effect of polymer glass-transition temperature (Tg) on the mechanical property performance of mortars containing calcium sulfoaluminate (CSA) cement and vinyl acetate/ethylene dispersible polymer powder (VAE DPP). Competitive products were acquired from companies A, B, and C. Company A supplied VAE DPP with glass-transition temperatures of 64°F (18°C) and 19°F (−7°C). Company B supplied VAE DPP with glass-transition temperatures of 59°F (15°C) and 5°F (−15°C). Company C provided VAE DPP with glass-transition temperatures of 68°F (20°C) and −8°F (−22°C). It is important to note that differences in glass-transition temperature result from differences in the ratio of monomers utilized for production of the liquid polymeric dispersion during reaction polymerization, where the pertinent ratio is that of ethylene to vinyl acetate for materials germane to this study. Additionally, each utilized polymer powder may also differ in constituent components comprising the polymer powder as a result of the drying process, where constituent materials should not be limited to products typically utilized for forming protective colloids or products utilized as anti-caking agents. Each polymer was tested in a standard mortar formulation with polymer/cement ratio of 2/5 and water/cement ratio of 0.48. Experimental results show that polymer modification improves the ductile performance of CSA cement mortars. Additionally, experimental results show that the glass-transition temperature of vendor-specific products influences the mechanical property performance of polymer-modified CSA cement mortars.

Polymer-Modified Cement Composites with Increased Resistance to Elevated Temperatures

The paper informs on partial results of the research focused on improvement of resistance of cement composites towards actuation of high temperatures invoked by formation of fire. Specifically it is an optimisation of cement composites with use of alternative raw material resources. These cement composites are primarily designed for reconstructions of reinforced concrete constructions. Basic characteristics were tested with specimens exposed in laboratory conditions to an ambient characterized with increased temperatures simulating fire in real construction.

Preparation and Properties of a New Polymer-Modified Cement Mortar Containing Iron Tailings Sand

Iron tailing is a kind of mineral waste from industrial processing and magnetic separation of iron ore, which severely pollute the air, soil property and the source of water. For large scale tailing ponds (dam height >100 m), the accident could cause a substantial damage. Therefore, it is significant to appropriately utilize the tailings. The present paper systematically studies the possibility of complete replacement of quartz sand with the iron tailings in polymer modified cement mortar used in external wall insulation plaster. The effects of redispersible polymer powers, cellulose ether, water reducing agent, lignin and polypropylene fiber on the performance of polymer modified cement mortar have been discussed. The results show that the performance of polymer-modified cement mortar composed of iron tailings has reached the national standard of external wall insulation system in China.

Recent Research on Polymer-Modified Cement Mortar in China

Polymer has been widely used in construction in China during the past few years and has become a necessary component of some building materials. The development in concrete-polymer composites (CPC) is going with the economical achievement and practical needs, which focuses on polymer-modified cement mortar (PCM). Therefore, this paper introduces the trends and advances in research on PCM during the past few years in China, especially cement hydration in the presence of polymer, the properties and application of PCM, waste utilization as well as trends of concrete-polymer composites.