Polymer Cement Mortar Research Articles

Core-Shell Morphology of Redispersible Powders in Polymer-Cement Waterproof Mortars.

Redispersible powders based on soft core-hard shell polymer particles can be used as additives in polymer-cement mortars. The role of this morphology on the spray-drying production of these powders and on the crack-bridging properties of the corresponding cement-based membranes is investigated. Different polymer latexes at high solid content with varied core-shell ratio, shell thickness and chemical composition (hardness) were prepared from styrene and 2-ethylhexyl acrylate monomers via semi-batch emulsion polymerization. The latexes were characterized in terms of size, composition, and glass transition temperature (T), and spray-dried to obtain redispersible polymer powders (RPPs) using poly (vinyl alcohol) and limestone powder as anti-caking agents. The polymer powders were mixed with a mortar mixture and redispersed in water to produce cement-based membranes, which were tested for crack-bridging properties at different temperatures. The results showed that it was not possible to spray-dry a dispersion of homogeneous polymer particles with T of −25 C, unless these particles are protected by much harder (high T) shell. In particular, it was observed that a thicker shell improved the spray-ability, but lowered the crack-bridging properties of the produced membrane. A trade-off between these two was revealed to be the key for the optimal design of the polymer nanoparticles, as proven by the systematic study of the core-shell morphology reported in this work. The best compromise was shown to consist of particles larger than 300 nm, shell thickness of about 5 nm, and core-shell ratio of 97%, with styrene content in the shell not larger than 80% to avoid excessive hydrophobicity.

Bonding behavior of CFRP grid-concrete with PCM shotcrete

This study reveals the bonding behavior and stress transfer mechanism of a carbon-fiber-reinforced-polymer (CFRP) grid with polymer-cement-mortar (PCM) shotcrete on reinforced concrete (RC) members. The influence of the number of CFRP grid points, the interval of the horizontal grid, the existence of a vertical grid and the type of PCM on the bonding behavior of CFRP grid concrete with the PCM shotcrete method are discussed. The test results indicate that the tensile force transmits to the CFRP grid using the vertical grid points in turn, acting on the concrete via the PCM. Meanwhile, the horizontal grids provide the mechanical occlusal effect in this process. Once the transmitted tensile stress exceeds the ultimate bonding stress between concrete and PCM, peeling damage will occur. In addition, the deformation followability of the low-elasticity PCM was better than that of the high-strength PCM. This study also determines the essential number of grid points when the bonding behavior of the CFRP grid concrete with the PCM shotcrete is sufficient.

Properties of Color Polymer Cement Mortar according to Polymer-binder ratio and Dosage of Pigment

Properties of Color Polymer Cement Mortar according to Polymer-binder ratio and Dosage of Pigment

Study on design formula of shear capacity of RC beams reinforced by CFRP grid with PCM shotcrete method

The objective of this study was to evaluate the shear capacity of reinforced concrete (RC) beams by using carbon-fiber-reinforced-polymer (CFRP) grid with polymer-cement-mortar (PCM) shotcrete. A new evaluation method of shear capacity based on the concept of effective strain of CFRP grid was proposed by RC beam tests, which were carried out with the reinforced arrangement of CFRP grid as parameters. In order to make this new evaluation method more applicable, we conducted a 3-dimensional finite-element (FE) analysis by incorporating factors such as the influences from shear span ratio of RC beams. Our results suggested that the proposed evaluation method by considering both vertical and horizontal grid was highly effective, and that the share ratios of shear capacity between vertical and horizontal grid presented a nonlinear relationship according to the shear span of RC beams.

Observation of the Development of the Elastic Modulus and Strength in a Polymer-Cement Mortar Using the Acoustic Emission Method

The paper describes an experiment focused on observing the development of the elastic modulus and compressive strength in a polymer-cement mortar during the first 28 days of aging. The specimens (aged 3 and 28 days) were tested for the static and dynamic modulus of elasticity using two methods – the ultrasonic pulse velocity test and the resonance method. During the test of the modulus of elasticity in compression the mortar’s behaviour was also examined by means of the acoustic emission method, which is based on the recording of mechanical pulses caused by dilation waves generated by microcracks that form during loading. The outcome of the experiment is an evaluation of the polymer-cement mortar’s behaviour in terms of the development of its elastic modulus and compressive strength as well as in terms of the material’s acoustic response during loading.

Influence of cement substitution by calcareous fly ash on the mechanical properties of polymer-cement composites

The aim of the presented research was to determine the influence of cement substitution with calcareous fly ash on the mechanical properties of polymer-cement composites. Coal combustion products such as calcareous fly ash have been already used in traditional cement composites as a part of cement and considered potential additions for concrete but its introduction into polymer-cement composites is still under preliminary investigation. The morphology of fly ash causes problems with its compatibility with polymer-cement binders but its insertion into those building materials is another way to utilize mineral combustion products that are cumbersome in storage and recycling. The influence of the mineral addition on polymer-cement composites containing 20% of polymer was especially taken into consideration. Mechanical properties of polymercement mortars modified with calcareous fly ash were tested after 28 and 90 days of curing. As a part of preliminary study, activity index of mineral addition was determined. Polymer-cement composites containing calcareous fly ash were characterized by higher flexural and tensile strength comparing to standardized mortar, even for the mortars containing 40% of mineral addition. The negative effect of the polymer-cement composites modification with calcareous fly ash was especially observed on the compressive strength of this composites.

08.41: Renewal method for aged steel bridges with polymer cement mortar

ABSTRACTThis research offers a new composite‐revamping method for railway bridges by assuming composite remodelling process of existing steel bridges having no specific fissure damages or serious corrosions and effectively making use of relatively new materials to it. Effects of noise reduction and improved stiffness were further confirmed through Impact tests (vibration and noise measurement tests) in order to prove the efficacy of the composite remodelling. By the tests, it can be confirmed that the composite structuring work tended to reduce the vibration level by around 10 to 35 dB and the all pass (AP) value by about 30 dB. In addition, the stiffness increases from the bridges of only steel members. The remainder life of the structure is extended by this effect. These effects are confirmed by the experiments for railway bridges.

On the in-plane shear response of the high bond strength concrete masonry walls

Conventional unreinforced masonry walls subject to in-plane shear loading fail due to exceedance of shear and tensile bond strengths. This paper examines whether or not the in-plane shear capacity of masonry walls would increase with the increase in the bond strengths through experimental and numerical investigations. For these investigations, shear walls were built with high bond strength polymer cement mortar; they were applied in thin layers of 2 mm thickness each. Material tests were carried out to characterise the bond and the compressive strengths of the high bond strength thin layer mortared masonry; the bond strengths were found approximately double that of the conventional 10 mm thick cement mortars. The shear walls, however, exhibited significantly lower capacity (contrasting the expectation) and displayed base course sliding mode of failure. To ascertain the validity of the experimental results, a combined surface contact—interface element micro finite element (FE) modelling technique was formulated; the results adequately reproduced the experimental datasets. The validated FE model was then applied to examine the effect of the aspect ratios and pre-compression levels to the failure modes, deformation and strength of the high bond strength shear walls and is shown that once the pre-compression exceeds 15% of the masonry compressive strength, the base sliding failure mode changes to the diagonal cracking mode with corresponding increase in in-plane shear capacity. Therefore, it is concluded that the increase the bond strength without regard to pre-compression could adversely affect the safety of the high bond strength unreinforced masonry shear walls.

Stainless and Galvanized Steel, Hydrophobic Admixture and Flexible Polymer-Cement Coating Compared in Increasing Durability of Reinforced Concrete Structures

The use of stainless or galvanized steel reinforcements, a hydrophobic admixture or a flexible polymer-cement coating were compared as methods to improve the corrosion resistance of sound or cracked reinforced concrete specimens exposed to chloride rich solutions. The results show that in full immersion condition, negligible corrosion rates were detected in all cracked specimens, except those treated with the flexible polymer-cement mortar as preventive method against corrosion and the hydrophobic concrete specimens. High corrosion rates were measured in all cracked specimens exposed to wet-dry cycles, except for those reinforced with stainless steel, those treated with the flexible polymer-cement coating as restorative method against reinforcement corrosion and for hydrophobic concrete specimens reinforced with galvanized steel reinforcements.

Estimation of reinforcing effects of FRP-PCM method on degraded tunnel linings

Fiber-reinforced plastic (FRP) is a practical alternative construction material that has been extensively adopted in the reinforcement of concrete structures. The reinforcing effect of FRP grids needs to be quantitatively estimated when the grids are applied to degraded tunnel linings to assist with the maintenance design. In the present study, the reinforcing effect of FRP grids embedded in Polymer Cement Mortar (PCM) shotcrete (the FRP-PCM method) on degraded tunnels was estimated. Laboratory direct shear tests and bending tests were carried out on specimens reinforced with various grades of FRP grids to obtain the mechanical properties of the bonding surfaces between the PCM and the concrete reinforced by FRP grids. The bending test results showed that the bearing capacity of beams reinforced by FRP grids subjected to bending loads improved by around 40%. A numerical modeling of the reinforced tunnels by the FRP-PCM method was performed using the properties obtained from these laboratory tests to investigate the reinforcing performance of the FRP-PCM method on degraded tunnel linings. Numerical models with different loosening pressures acting on the tunnel lining, ground classes, degrees of lining deterioration, and degrees of tunnel health were considered, and the suitable conditions under which the application of the FRP-PCM method could effectively reinforce tunnel linings were proposed.

Comparison of Measurements Methods Intended to Determination of the Shrinkage Development in Polymer Cement Mortars

The paper deals with the experimental determination of the shrinkage progress of the polymer cement (PCC) mortars. The main motivation of performed measurements was to compare the results obtained from two different measurement procedures based on the measurement of the relative length changes and relative mass losses of the test specimens during whole time of ageing. Performed experimental analysis, focused on the determination of the progress of the relative length changes and relative mass losses, showed advantages and disadvantages of investigated measurement procedures. All performed measurements exhibited almost the same total progress of relative mass losses regardless of the used test procedure and size of specimens. The differences in the relative length changes originated from the capabilities, limitations and regulations of particular measurement procedures.

EXTERNAL FLEXURAL STRENGTHENING OF RC BEAMS USING BFRP GRIDS AND PCM

External strengthening of Reinforcement Concrete (RC) structures using epoxy-bonded Fiber Reinforced Polymer (FRP) sheets has some negative aspects, such as interfacial debonding and poor resistance ability of epoxy resin for fire and ultraviolet (UV), in addition to the working environment restrictions. To overcome some of those negative aspects, FRP grid bonded with Polymer Cement Mortar (PCM) to strengthen RC structures is developed and proposed in this study. The main objective of this paper is to study the efficiency between Basalt FRP grids and PCM in the flexural strengthening of RC beams. A tensile test was first conducted to determine the static longitudinal tensile strength and maximum elongation properties of the different BFRP grids. Then, the well-known double shear test was conducted to determine the bond mechanism between BFRP grids and concrete. Finally, the flexural behavior of the RC beam externally strengthened with BFRP grids was investigated through a four-point bending test. The results showed the efficiency of using BFRP grids as external strengthening method, as well as the stress-strain relationship of RC beams cross-section shows the compatibility with flexural theory.

The use of the acoustic emission method for the monitoring of changes in the internal structure of polymer-cement mortars when testing the static compressive modulus of elasticity

The paper focuses on the experimental determination of the dynamic and static compressive modulus of elasticity of selected polymer-cement mortars and their comparison. The dynamic modulus of elasticity was determined by means of the ultrasonic pulse velocity test and the resonance method. The static compressive modulus of elasticity test was accompanied by a measurement of the material’s behaviour using the acoustic emission method, the principle of which is the detection of mechanical dilation waves produced by changes and microscopic faults in the structure of the material. The advantage of the acoustic emission method is the possibility of detecting a crack before it can be found e.g. using a microscope. The outcome of the experiment is a detailed evaluation of the behaviour of polymer-cement mortars made using the values of the elastic modulus and acoustic response of the material during loading.

Prediction of Drying Shrinkage Cracks of Steel Chip Reinforced Polymer Cement Mortar

Prediction of Drying Shrinkage Cracks of Steel Chip Reinforced Polymer Cement Mortar

Study on Shear Behavior of Concrete-polymer Cement Mortar at Elevated Temperature

In this experimental and analytical work, interfacial shear strengths were evaluated at material and member level. Bi-surface shear strength was performed at material level and three-point bending test was conducted at member level. Beams were strengthened by adding steel reinforcement at soffit level and covered by spraying polymer cement mortar (PCM). After curing, strengthened RC beams were exposed to 60 ℃ for 24 hours and tested in three point loading test. Flexural capacity, load deflection relationship and failure modes were observed and compared with the strengthened beams tested at 20 ℃. Reduction in flexural capacity was observed with temperature, failure mode was also shifted from flexural mode to debonding mode of failure at elevated temperature. Ultimate shear load and failure modes were predicted by truss analogy approach. Debonding model was proposed by incorporating bi-surface interfacial shear strength, close agreement were observed between experimental and predicted values.

Investigation on concrete-PCM interface under elevated temperature: At material level and member level

This paper summarizes the experimental and analytical investigation on performance of polymer cement mortar (PCM)-concrete interfaces and PCM overlaid reinforced concrete (RC) beams at temperature level of 20, 40 and 60°C. At material level, bonding were tested by conducting interfacial split tensile strength test and bi-surface shear strength test. At member level, bonding was tested by conducting four point bending test of RC beam strengthened by overlaying with PCM on tension faces. Temperature showed significant effects on both levels of tests and reduction in strengths were observed with increase in temperature. Prediction formulas for interfacial strengths of materials were proposed and verified at all temperature levels. Ultimate shear loads and failure modes were analytically calculated by the truss model approach and were compared with experimental observations. Very close correspondences were observed at temperature of 20, 40 and 60°C.

Repair Mortar for Structural Sustainability

Objectives: Study on the engineering properties of fiber reinforced polymer cement mortar with incremental replacement of cement by silica fume, Granulated Blast Furnace Slag (GGBS) and Metakaoline (MK). Methods/Statistical Analysis: Cement is replaced by the additives as 5, 10 and 15 percent by weight. Polymer content (SBR) was varied as 5, 10, 15 and 20 percent by weight of water to be added. The FRP fiber addition is optimized to one percent by weight of cement in all the specimens. The intention was to study the variation in engineering properties of fiber reinforced polymer with additive replacement of binder with the additives and water with polymer. Findings: It is concluded from the test results that the compressive and flexural strength of modified mortar were improved markedly with increasing polymer binder ratio and also additive replacement of binder weight by silica fume, GGBS and Metakaoline. The results obtained has given much higher values when compared to individual addition of additives or polymer. The consistency in values of both compressive and flexural strength marks the much higher efficiency of the mortar even in lower percentage of addition of additive or polymer when added individually. Supplementary Cementing Materials (SCM) have growing importance in the construction industry, as it upgrades the economic and engineering efficiency of cement compositions. The replacement of water with polymer reduces the water binder ratio, driving to high strength and durable repair mortars. The polyester fibers addition resulted in the improvement of the mechanical properties of the composition. Applications/Improvements: Thus the fiber reinforced mortar combination is a mark in structural sustainability of not only modern but also for structural rehabilitation of historic monuments, where it can replace the ancient lime mortars with high strength and durability hand in hand.

A Functional Polymer Cement Mortar for Repair of Partially Damaged Asphalt Pavement

A newly polymer cement mortar to repair the rutting and bump of the pavement was developed and studied. In order to satisfy the required performance of the asphalt pavement as repair material, the polymer cement ratio of this mortar went up more than fifty percent. The basic properties such as workability, mechanical properties and adhesion durability of the polymer cement mortar was firstly investigated. Subsequently, the dynamic stability of the composite specimens repaired by the polymer cement mortar was clarified by wheel tracking tests. Finally, the availability of this mortar applied for the repair of the pavement was confirmed by the track running test more than two years.

STRUCTURAL PERFORMANCE OF DAMAGED OPEN-WEB TYPE SRC BEAM-COLUMNS WITH BOLT-CONNECTED BATTEN STEEL PLATES AFTER RETROFITTING

In this paper, structural performance of damaged SRC beam-columns with open-web type of batten steel plate after retrofitting was investigated. Three open-web type SRC beam-columns with bolt-connected batten steel plates were fabricated and tested under combined constant axial load and cyclic lateral load. At first, each beam-column was cyclically loaded to the targeted displacement. After the first loading, the test columns were retrofitted and reloaded till large deformation or failure. The damaged portion of each column was retrofitted with the polymer cement mortar and epoxy resin was injected into the cracks. The measured stiffness of retrofitted columns varied between 71.4% and 85.5% of the initial one. And, test results also indicated that the column which experienced the larger displacement and higher axial load showed lower load carrying capacity, but the others showed approximately the same capacities as the initial columns. Numerical analysis was also conducted to explain the retrofitted columns. Analytical results predicted the experimental behavior fairly well, which verifies the validity of the analytical models in low axial load.

The Effect of Nano-Silica Particles on Fresh and Hardened State Properties of Polymer Cement Mortars

Ethylene vinyl acetate (EVA) was used in the amounts of 5, 10 and 15% of the cement content in the production of polymer cement mortars. Besides, nanosilica, in three different sizes of 35, 17 and 4 nm, were included in the mortars. The addition of nanosilica particles in polymer cement concretes and mortars affects both fresh and hardened state properties. The extremely high surface area of nanoparticles increases the water demand; hence to obtain a workable mixture it is necessary to increase the superplasticizer used. In the hardened state, the strength and impermeability properties improve due to both pozzolanic reaction and filler effect of nanosilica particles as well as polymer film formation. The flow properties in the fresh state and flexural and compressive strength properties in the hardened state were determined.