Polymer Mortar Research Articles

Experimental study on bond performance of advanced material based on composite Portland cements developed for anchoring systems with post-installed reinforcement bars in concrete

Abstract This paper presents an assessment study on the bond performance of new advanced mortars based on composite Portland cements. These developed mortars are used as anchoring material for post-installed reinforcement steel bars in concrete. The anchoring mortars were developed by laboratory studies in the recent years and they met several performance criteria regarding the properties in plastic state as consistency, cohesiveness, stability and in hardened state as strength, rigidity, deformation volume and bond to support. Anchoring systems with post-installed reinforcement steel bars are obtained through installation of reinforcement bars into drill holes in hardened concrete and filled with flowable mortars which may be polymer or cement-based mortars. Generally, post-installed reinforcement bars are used to connect layers of new concrete to old concrete and also new members to old concrete members. So far, the most employed anchoring material is the polymer-based chemical resin which have some undisputed advantages, but the durability and long-term performance along the expected service life is questionable. Recently, inorganic-injection-type anchors have been developed in Japan. These anchors are composed of cement, aggregate and additive agents. In this study, the employed anchoring-mortars are exclusively based on hydraulic binder, namely composite Portland cements which are included in the European class of cement CEM II. These composite cements contain supplementary cementing materials (SCM) as fly-ash or limestone which are combined with Portland clinker at the manufacture. The bond strength of the reinforcement steel bars was assessed based on the prescriptions provided in the European assessment document EAD 330087 and EN 1881. These two technical norms are limited only to deformed reinforcement bars with characteristics in conformity with EN 10080 and designed based on EN 1992-1-1. Within this study, the shear load on the reinforcement bars post-installed into hardened concrete is not considered.

Modifying the pore size distribution in Fe-rich inorganic polymer mortars: An effective shrinkage mitigation strategy

Inorganic polymer (IP) binder is formed upon alkali-activation of Fe-rich (41 wt%) metallurgical slag leading to materials with mechanical properties comparable to ordinary Portland cement binders. Crack formation is reported in IPs, which can be related to volumetric stability, which is to date not thoroughly understood in IPs. This study determined the autogenous and drying shrinkage of IP mortars. Shrinkage mitigation strategies, such as the addition of 2-methyl-2,4-pentanediol (2MPL), blast furnace slag (GGBFS), and applying heat curing, were used separately or in combination. IP mortars exhibited autogenous expansion and high drying shrinkage. The addition of 2MPL led to a porosity increase, as air was entrained, decreasing the drying shrinkage with 64%. Additional heat curing had no effect on samples with 2MPL. Introducing GGBFS resulted in smaller pores, increasing drying shrinkage. Shrinkage in IP mortars is driven by its pore size distribution and higher shrinkage resulted in lower flexural strength.

Prediction of Pipe Stiffness of Glass Fiber Reinforced Polymer Mortar Pipe Using Laminate Plate Theory

Prediction of Pipe Stiffness of Glass Fiber Reinforced Polymer Mortar Pipe Using Laminate Plate Theory

Innovative seismic strengthening of historic masonry walls using polymer mortar and steel strips

Appropriate selection of strengthening methods for existing historic masonry structures is of utmost importance to improve the seismic behavior without altering their aesthetics. The present research was aimed to study the in-situ strengthening methods applicable to seismic strengthening for historic masonry buildings. The strengthening methods include embedment of polymer mortar, steel strips bonded by polymer mortar and a combination of both into bed joints. To assess the effectiveness of the strengthening methods, a detailed experimental investigation on one un-strengthened and four strengthened masonry walls were carried out under cyclic lateral loads. The effectiveness of strengthening methods was evaluated by comparing failure modes and seismic performance, in terms of strength, deformation capacity, stiffness degradation, energy dissipation and equivalent viscous damping. It was found that presence of high strength polymer mortar improved the deformation behavior of masonry walls, whereas, the specimens strengthened with steel strips significantly enhanced the strength, deformation and energy dissipation capacity. The adopted strengthening methods showed insignificant influence on the initial stiffness of the masonry walls. Based on the observed damage and failure, empirical expressions were established to predict the in-plane shear capacity of the strengthened masonry walls and were verified with the previous experimental results.

Mechanical Properties and Microstructure of a Metakaolin-Based Inorganic Polymer Mortar Reinforced with Quartz Sand

The synthesis, mechanical behaviour, and microstructure of metakaolin-based geopolymer mortar reinforced with quartz sand are presented in this investigation. Fine sand (quartz sand) aggregate were added in different proportions of 50, 60, 70 or 80 wt.% to prepare the fresh metakaolin-based geopolymer paste. The geopolymer mortar was achieved by a mixture of geopolymer paste and river sand in the ratio 2:5 by mass. The mixture of sodium hydroxide solution (10 M) and sodium silicate solution (Na2SiO3) in a volume ratio of 2:3 was used as an alkaline activator. All the specimens were cured at room temperature and tested after 28 days of curing. The investigations on microstructure and physical properties indicated a significant reduction of the open pores and interconnection of micro and meso cracks in the structure network with increase in the amount of quartz sand. As a consequence, the samples show a good mechanical strength principally with the addition of 60 wt.% of quartz sand to binder with values of 8 and 66 MPa for flexural strength and compressive strength, respectively.

Rheological behavior of fresh latex polymeric mortar by squeeze-flow technique

This work reports the first experimental effort using the squeeze-flow technique for evaluating the rheological behavior of latex polymeric mortar. Polymeric mortar (PM) is a new class of building material used for laying bricks on non-structural walls replacing Portland cement mortar. The rheological behavior of using fresh PM as a function of the latex resin content was assessed by squeeze-flow technique. Samples were tested at two displacement rates (0.01 mm/s and 3 mm/s), up to a maximum displacement of 9 mm. The results indicated that the squeeze-flow technique is a viable method for the rheological characterization of fresh polymeric mortar. Rheological parameters such as viscosity and yield stress were determined successfully. Mortars with a higher resin content were more difficult to deform, resulting in higher loads. Furthermore, the viscosity as well as the yield stress showed a strong positive linear correlation with the resin content of the PM. The test results suggest that the rheological parameters are sensitive to displacement rates. The lowest displacement rate (0.1 mm/s) resulted in lower deviations, higher viscosity and lower yield stress.

Polymer repair products containing fly ash contaminated by denitrification process

The increase in the emphasis on the quality and long life of buildings and structures opens space for the development of new and progressive renovation materials. Current trends focus on using the by-products of thermal powerplants, fly ash (FA), produced by the combustion of pulverised coal, which is contaminated by the denitrification of the fumes. Because ammonia escapes from the concrete containing contaminated fly ash, further use of the fly ash in concrete or as a partial cement replacement is problematic. The most advantageous use of FA seems to be as a filler in polymerous materials. For this reason, this paper focuses on verifying new ways of using FA as a filler in polymer mortars and concretes, which are then used as structural and non-structural repair products and systems, according to the European Standard EN 1504–1. By studying four different types of FA, we found that FA, neither from high-temperature combustion nor fluid, contaminated by flue gas denitrification process does not deteriorate the properties of epoxy resin polymer repair products. Successful use of these by-products was proved by comparing the results of the physical and mechanical parameters of the polymer mortars containing contaminated FA with the reference polymer mortars containing only primary raw materials and polymer mortars with FA unaffected by the denitrification process. Computed tomography (CT) was used to analyse the microstructure and bond strength of the developed materials to underlying concrete surface; it was also confirmed that weather does not degrade the developed materials. Scanning electron microscopy (SEM) supported by dispersion spectral analysis proved that distribution of individual elements of filler in the developed repair products is even and FA particles were successfully incorporated in the enclosed structure of the polymer matrix. New materials are economically beneficial because a large amount of by-products are used in their composition (up to 60% by weight). They are capable of replacing a considerable proportion of the epoxy resin, which is the most expensive component of the material. In this way, a new possibility was developed for using contaminated FA as well as new polymer repair products and systems with excellent parameters.

Assessment of chloride-induced reinforcement corrosion protection of modified sulfur polymer composites

The present study deals with the corrosion behavior assessment of steel reinforcing bars embedded in modified sulfur polymer-based mortars with and without microfillers. Modified sulfur was used as the primary binder, while silica fume, metakaolin, and fly ash were used as the microfillers in the sulfur polymer composites. The comparison was made with Portland cement mortar (CM). The modified sulfur polymer mortars formulations used were plain sulfur mortars (SM), sulfur-silica fume mortar (SSM), sulfur-metakaolin mortar (SMM), and sulfur-fly ash mortars (SFM). The reinforced samples were exposed to 5% calcium chloride (CaCl2) solution for 52 weeks (~365 days). The corrosion states of rebars embedded in sulfur, as well as Portland cement mortars, were estimated in terms of electrical resistivity (ER), half-cell potentials, corrosion current density based on linear polarization resistance (LPR) test, and visual inspection of steel rebars and mortar samples. Besides, comprehensive analysis based on Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy were also performed on samples collected from the steel-mortar interface of all specimens. The results revealed that the rebars embedded in sulfur-based mortars underwent less corrosion-related deterioration compared to Portland cement mortars. Moreover, the inclusion of microfillers improved the corrosion inhibition performance of sulfur-mortars. Furthermore, deterioration effects were observed to be lower due to improved sorptivity values. The corrosion inhibition effect of mortars was observed to be decreasing in the order SSM > SMM > SM > SFM > CM.

The Influence of Crystalline Admixtures on the Properties and Microstructure of Mortar Containing By-Products

Crystalline admixtures and industrial by-products can be used in cement-based materials in order to improve their mechanical properties. The research examined long-term curing and the exposure to environmental actions of polymer–cement mortars with crystalline admixture (CA) and different by-products, including Bengħisa fly ash and Globigerina limestone waste filler. The by-products were introduced as a percentage replacement of the cement. A crystallization additive was also added to the mixtures in order to monitor the improvement in durability properties. The mechanical properties of the mortar were assessed, with 20% replacement of cement with fly ash resulting in the highest compressive strength after 540 days. The performance was analyzed with respect to various properties including permeable porosity, capillary suction, rapid chloride ion penetration and chloride migration coefficient. It was noted that the addition of fly ash and crystalline admixture significantly reduced the chloride ion penetration into the structure of the polymer cement mortar, resulting in improved durability. A microstructure investigation was conducted on the samples through Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS). Crystals forming through the crystalline admixture in the porous structure of the material were clearly observed, contributing to the improved properties of the cement-based polymer mortar.

Analysis of Mechanical Properties of Fiber Reinforced Polymer Mortar

It is studied that effects of different amounts of steel fiber and glass fiber on the compressive strength, flexural strength, and compression ratio and bond strength of styrene-acrylic emulsion modified mortar under different ages. The results show that the compressive strength, flexural strength and bond strength of mortar increase with the increase of steel fiber content, and the toughness improvement effect is obvious. With the increase of glass fiber content, mortar compressive strength, flexural strength and bond strength first increases and then decreases. Combined with SEM analysis and theoretical calculation to analyze the mechanical strength mechanism of fiber reinforced polymer mortar.

Flexural strengthening of reinforced concrete beams with high-strength steel wire and engineered cementitious composites

The rehabilitation of reinforced concrete (RC) members with high-strength steel wire and polymer mortar is a popular method for structural strengthening, owing to the resultant high strength and good fire resistance. However, similar to cement mortar, polymer mortar is a brittle material in tension. Further, its use as the strengthened layer will lead to the corrosion of the steel wire, as well as secondary corrosion of the steel reinforcements in existing RC members. This study proposed a novel method for flexural strengthening existing RC members through the employment of high-strength steel wire and high ductile engineered cementitious composites (ECC). The influences of the matrix type of the strengthened layer, reinforcement ratio of the steel wire, and existence of pre-damage on the flexural behaviours of the beams were tested and analysed in detail. It was found that the flexural strength and stiffness of the strengthened beams were significantly higher than those of an unstrengthened control beam. The substitution of polymer mortar with ECC at the strengthened layer not only changed the crack pattern at the strengthened layer (i.e. multiple and fine cracks in the ECC layer, as compared to fewer and larger cracks in the polymer mortar layer), but also delayed the crack development in the concrete tension zone. Finally, the flexural strengths of the strengthened beams were calculated based on the design code GB 50367-2013. It was found that the current design code can predict the flexural strength of the beams with high accuracy.

Behaviour of Different Nanomaterials in Geopolymer Concrete

In stock, because of the low carbon dioxide radiation, geopolymers are very important worldwide as a building material, unlike Portland cement. Today, nanotechnology is an indispensable feature in the field of building management. It has observed that several nanomaterials influence various properties of cement-based concrete. Fly ash-based geopolymer- concrete is an option for cement-based concrete, and nanoparticles change the properties of geopolymers. Nanomaterials, such as CNTs, nano-silica, and graphene, combined with gene polymer mortars, significantly improve their properties. NanoTiO2, when found, acts as a photocatalyst. Particularly nanomaterials such as nano-silver act as anti-bacterial agents. The functions of several nanomaterials have been studied and discussed to change the properties of geo-polymer concrete and mortars.

Experimental study of seismic behaviour of renovated masonry structures after removing walls and seismic retrofitting

Structural renovation is an economic choice to expand space of existing masonry buildings. To this end, removing bearing walls and seismic strengthening are required in engineering practice in seismic-prone areas. Therefore, in the paper three 1/2-scale two-bay two-storey planar masonry structures, consisting of one original structure and two structures with proposed renovation schemes, were fabricated and tested under cyclic loading. The original structure consisted of brick masonry units, ring beams, and tie-columns. The first renovated structure was designed by removing two bearing walls at the ground storey, adding two short-width shear walls, and enlarging the beam sections. The second renovated structure was achieved by removing one wall in the ground storey, enlarging the sections of confined beams and columns to form a single-bay frame, and retrofitting the adjacent wall with reinforcement layers and polymer mortar. Results indicate that all three specimens demonstrated hysteretic behaviour with pinching phenomenon. Energy dissipation capacity of the two renovated structures were both higher than that of the original structure prior to 1% drift, in particular for the first renovation scheme. In comparison, the second renovation scheme more evidently improved structural resistance, but it made the ultimate deformation capacity smaller than the original structure because the stiffness of the renovated ground story much larger than that of the second story resulted in failure concentration at the 2nd floor. Thus, it is more economic to make the lateral stiffness of the two storeys compatible during the design of renovation and strengthening.

Interlayer bonding improvement of 3D printed concrete with polymer modified mortar: Experiments and molecular dynamics studies

The inherent weak interfaces between adjacent layers by the laminate stacking process of 3D concrete printing hinder this advanced technique for general engineering applications. In this study, polymer-modified mortars were fabricated to improve the weak interlayer bonding performances. The effects of the setting time of the printed concrete and changes of the interlayer moisture were tested. Both epoxy resin- and chloroprene latex-modified mortars were prepared and used as interlayer interface enhancement materials according to different interlayer intervals. The direct tensile and shear strengths of the polymer mortar-strengthened interfaces were tested and evaluated by the crossover test. Moreover, the effects of the moisture released from the surface of the cement-based composite materials on the interlaminar bonding properties and the enhancing mechanism of the epoxy resin- and chloroprene latex-modified mortars were simulated through molecular dynamics and density functional theory. The results demonstrate that the electrostatic interaction (Coulomb force) between the epoxy resin and calcium ions from hydrated calcium silicate counteracts the weakening effect of water molecules (surface moisture) on the interlaminar bonding, thus improving the interface bonding of printed concrete. The optimal polymer mortar that strengthens the interfaces most effectively was identified.

Experimental study and modeling of bond of carbon-fiber-reinforced polymer grids to polymer mortar at room and elevated temperatures

Carbon-fiber-reinforced polymer grids encased with polymer mortar have received much attention lately as an effective technology for strengthening concrete structures. The objective of this study was to investigate the bond-slip behavior of carbon-fiber-reinforced polymer grids to polymer mortar at room and elevated temperatures. First, 20 pull-out specimens were tested at room temperature of 20°C, and the investigated parameters included the type of carbon-fiber-reinforced polymer grids, the embedment length of longitudinal bar, and the transverse bar length. Based on the experimental results, a two-branch bond-slip model at room temperature was proposed, with the characteristic bond stress and the corresponding slip determined by the regression analysis of test data. Second, 24 pull-out specimens were tested at elevated temperatures over a range of 20°C–300°C, and the investigated parameters included the type of carbon-fiber-reinforced polymer grids and the testing temperature. Based on the experimental results, a bond-slip model at elevated temperatures was further proposed by modeling the temperature-dependent reduction factors. The two proposed bond-slip models will be particularly useful in the theoretical analysis of structures with carbon-fiber-reinforced polymer grids and polymer mortar strengthening system under both room and elevated temperatures.

Experimental study on dehumidification and chlorine-removal efficiency of conductive polymer mortar

This paper represented a conductive polymer mortar used in wet environment prepared from the raw materials include waterborne epoxy emulsion, styrene-acrylic emulsion, carbon fiber, carbon black, silica fume, cement, etc. The effects of conductive filler content, polymer emulsion content and cement/sand ratio on the toughness, conductivity and waterproof performance of mortar were studied by single-factor tests. The dehumidification and chlorine-removal efficiency of mortar through electroosmosis and electrothermal under 60 V DC voltage were focused on. The results show that the conductive polymer mortar has better dehumidification and chlorine-removal performance than common mortar and the resistivity is the main influential factor. The optimum content of conductive filler and polymer emulsion are 1.2% and 15% respectively. In addition, conductive polymer mortar has good humidity sensitivity, and there is a strong correlation between humidity and resistivity change rate.

Study of properties of polyethylene and cement mixtures

Polyethylene is used in a myriad of ways, from low molecular weight polyethylene (PE) being used as a lubricant and mold release, to higher molecular weight grades being used for fiber, films, molding resins, etc. According to the advantages of PE as stiffness, light weight plastic and having excellent chemical resistance, polyethylene and cement mixtures can offer considerable benefits to product performance, marketing aspects and differentiation of cement products. The objective of this investigation is to study the influence of PE on the properties of cements. In this paper a portion of ordinary Portland cement OPC was replaced by polyethylene powder, with four different rates (5%, 10%, 15% and 20%). Paste of each cement was prepared and analyzed for its setting time, expansion and strength. In this experimental study with 10% of PE the maximum strength is achieved for 28 days. Moreover, in order to benefit from thermoplastic and viscoelastic properties of PE, we exposed specimens of polymer mortar to a thermal cycle in a temperature ranging from 25 up to 130 °C. The results show some development of strength.

Influence of Activator on the strength of Ultra Fine Natural Steatite Powder based on Geopolymer Mortar

In this study the detailed analysis was made on alkali activated ultra fine natural steatite powder (UFNSP) mortars. The activating alkali was prepared through sodium hydroxide and sodium silicate with different molarities concentration of NaOH. The molarities of NaoH are various from 8, 10, 12, 14 and 16. The proportion of sodium hydroxide and sodium silicate proportion are fixed 1:2.5. Further the strength gained was accelerated through polyvinyl alcohol [PVA]. And various water binder ratio of 0.5, 0.6, 0.7, 0.8 and 0.9 with addition of PVA. For workability purpose super plasticizer was used, here Poly carboxylic ether was used as a superplasticizer. These various ratios concentration of alkali activators were tried on compressive strength of polymer mortar and the results were discussed. The watched outcomes demonstrate that, increment in sodium hydroxide content in soluble base fluid expands the strength. Exhibit the outcome was effect of Si/Al proportion on compressive strength of the specimen with various water binder proportions. In general, the study shows that integrating low ratio of Si/Al content in UFNSP with PVA can fetch low binding property on alkali activator UFNSP material.

Characterization and Performance of Mechanical Properties of GGBS Based Geo Polymer Mortars

From decades it has been recognized that Geopolymer will considerably replace the role of cement in the construction industry. In general, Geopolymer exhibits the property of the peak compressive strength, minimal creep and shrinkage. In this current research paper, Geopolymer mortar is prepared by using GGBS and Fly ash. The mix proportions are of (100-60)%GGBS with Fly ash by 10% replacement. The alkali activators Na0H and Na2Sio3 are used in the study for two different molarities of 4&8. The ratio to Sodium silicates to sodium hydroxide is maintained from 1.5, 2, 2.5 & 3 were used. Mortars are prepared and studied the effect of molarities of alkali activators in their setting times and strengths.

Study of the polymer mortar based on dredged sediments and epoxy resin: Effect of the sediments on the behavior of the polymer mortar

Several studies have shown the potential of upgrading sediments in the civil engineering field. However, the complexity of sediments represents a scientific challenge in terms of their management. This study presents the river sediments recovery in a thermosetting matrix. The characterization results epoxy mortars show the feasibility of incorporating dredged sediments up to 50% substitution rate of natural sand. Moreover, according to the physic, mechanical, thermal and chemical evaluations of the thermosetting matrices, it appears that the performances depend on the factors of the rate of resin and the rate of sediments used. Indeed, the difference between the performances of resin mortars containing sediments and mortars without sediments is reduced by a resin content equal to 18%. In comparison with cementitious matrix mortars, the performances of polymeric mortars are well above. Finally, the SEM observations of different formulations made it possible to explain the results observed at the macroscopic scale.