Polymer-modified Concretes Research Articles

Natural Rubber Latex-Modified Concrete with PET and Crumb Rubber Aggregate Replacements for Sustainable Rigid Pavements

There are ongoing research challenges for the addition of the blend of PET and crumb rubber in polymer-modified concretes, which aims to leverage the benefits of both materials. In this study, various percentage combinations of waste aggregates, such as PET and crumb rubber, were used to replace coarse and fine aggregates in natural rubber latex (NRL)-modified concrete. Engineering properties such as compressive and flexural strengths, modulus of elasticity, and toughness obtained from compressive- and flexural stress-strain curves were investigated. Scanning electron microscopy (SEM) analysis was performed to examine the microstructural properties and study the strength development of the studied concretes. The results revealed that the compressive and flexural strengths of NRL-modified concretes with PET and crumb rubber aggregate replacements decreased with increasing replacement ratios. SEM analysis indicated that PET and crumb rubber (hydrophobic and non-polar materials) can affect the microstructure of the studied concrete by creating a weak interface between the aggregate and cement pastes, leading to reduced strength development. With the addition of the NRL additive, the film formation was found to act as a bridge and improve the bond strength of aggregates and hydration products in NRL-modified concrete. Furthermore, the integration of PET and crumb rubber aggregate can enhance the ability of the concrete to absorb energy and improve ductility. It was found that 10% of PET and crumb rubber aggregate replacement can be used for NRL-modified concrete as a rigid pavement, as its mechanical strengths satisfy the requirements set by the Department of Highways (DOH) in Thailand. This research helps repurpose waste materials and reduce the environmental footprint of concrete production.

Fine-Grained Polymer-Cement Basalt Fibrous Concrete for 3D Printing

The construction concrete printing requires new approaches at reinforcement performing. Only successful integration of the existing reinforcement systems will provide for the opportunity to design concrete structures and make objects with the help of additive technologies. The paper dwells upon the issues of possibilities and the efficiency of disperse reinforcement with basalt fibers. It presents a composition of a composite material for 3D printing of a type of fine-grained fibrous concretes with the required technological properties: a necessary plasticity and a high plastic strength for printing large-dimensioned items and structures without timbering by means of extrusion with a high material adhesion between the layers and controlled setting periods. The author studied a possibility to reclaim basalt fiber production wastes as a high-disperse fibrous filler for the reinforcement of polymer-modified concretes. The article provides the dependence of plastic strength on the fiber content in concrete. The authors consider the influence of components and the mechanism of modifying disperse particles of basalt fibrous concrete at obtaining the material for 3D printing. The obtained polymer-modified basal fibrous concrete has a good impact resistance, low water absorption and high crack resistance.

Mechanical properties of polymer-modified porous concrete

In this research work, polymer-modified porous concretes (permeable concretes) using polymer latex and redispersible polymer powder with water-cement ratio of 30 %, polymer-cement ratios of 0 to 10 % and cement content of 300 kg/m3 are prepared. The porous concrete was tested for compressive strength, flexural strength, water permeability and void ratio. The cubes size of specimen is 100 mm ×100 mm × 100 mm and 150 mm × 150 mm × 150 mm while the beam size is 100 mm × 100 mm × 500 mm was prepared for particular tests. The tests results show that the addition of polymer as a binder to porous concrete gives an improvement on the strength properties and coefficient of water permeability of polymer-modified porous concrete. It is concluded from the test results that increase in compressive and flexural strengths and decrease in the coefficient of water permeability of the polymer-modified porous concrete are clearly observed with increasing of polymer-cement ratio.

Design and Development of Concretes for Special Rehabilitation Tasks

The requirements for concrete restoration are not only aspects of retrofitting or restoration of bearing capacity but also aspects of preservation of historic structures, such as industrial monuments or civil engineering structures and buildings of the 1960s [1]. Thereby the facsimile replication of the concrete surface is a particular challenge. For the manufacture of delicate and complex structures with restricted accessibility self-compacting concrete (SCC) is well suited [2]. A modification with polymers normally ensures the durability of repair mortars or concretes (PCC) [3]. The combination of PCC and SCC to the Polymer-modified Self-Compacting Concrete (PSCC) for the restoration of historic concrete constructions is the logical consequence, to combine the advantages of both materials and is therefore an interesting alternative to well established materials and methods. Historic concrete constructions are often manufactured of concretes with very stiff consistencies, the so called tamped concretes. So there is a need to develop materials and methods for the rehabilitation of structures made of tamped concrete. For this reason, first investigations have been performed to the recipe development and optimization of its composition, but also properties, furthermore to the design possibilities and how polymers influence the concrete properties. In Germany between 1920 and 1970 industrial buildings and hydraulic structures have been built with concretes, where the content of Portland cement clinker was nearly complete substituted by latent hydraulic materials. The binders of those concretes contain large quantities of blast furnace slag and calcium sulphate and are called super-sulphated cement (SSC). Because of the high sulphate content, the compatibility of concrete structure with SSC is not given to concretes or mortars with other cements. If there is an adequate range of moisture, harmful new formations of phases will occur in the contact zone between SSC-concrete and the other concrete. In the field of rehabilitation PCC are well established. These are polymer-modified mortars or concretes with Portland cement, which are not suitable for the rehabilitation of structures of SSC-concrete. An alternative is the polymer-modification of SSC-concretes with polymers.

An Investigation on In-situ Strength and Bonding Strength of Polymer Modified Concretes (PMC) as Repair Overlays on Conventional Concrete Substrate

Polymer modified concrete (PMC) consists of Portland cement concrete with a polymer modifier. Its advantages are proper bonding strength to substrate concrete, high tensile and flexural strength and low amount of shrinkage and permeability. Using PMC overlays can be considered as a method for preservation of damaged concrete structures due to their suitable performance and durability. In this research, 24 mix designs of polymer modified concrete as the repair overlay containing two different types of modifier polymers (Styrene butadiene rubber (SBR)-based and Acrylic-based polymers) with different replacement percentages and various amounts of silica fume was considered to investigate the effect of type and amount of polymers and also presence of silica fume. The in-situ strengths are obtained by the Pull-off Method in different conditions of presence of cores and without cores on cubic samples and without cores on repair overlays. The bonding strength of repair overlays to the substrate is also assessed and a formula is presented for prediction of bonding strength and in-situ strength by consideration mechanical properties.In both polymer modifiers, maximum bonding occurred in the presence of polymer with 20% of cement weight. SBR-based PMC showed stronger bonding compared to the Acrylic-based PMC.

Evaluation of Rut Resistance of Polymer-Modified Asphalt Concretes

The rutting is a significant damage mechanism showing longitudinal furrows along with both wheel paths on asphalt pavement surface. To prevent the rutting under heavy traffic condition, polymer-modified asphalt (PMA) concretes were introduced in asphalt pavement industry. To measure rut resistance of asphalt concretes, the asphalt pavement analyzer (APA) and the deformation strength, SD, were used in this study. The SD was measured by Kim Test, a simple static-loading test, on the 150 mm-diameter cylindrical specimens at 60oC and APA test was performed for the same material. The PMA concretes were found to show improvement in SD and APA rut resistance by more than 50% and 60%, respectively. The SD and APA rut depth showed a relatively high correlation (R2 = 0.81) each other at 60°C. Therefore, it was possible to estimate rut tendency of normal asphalt and polymer-modified asphalt concretes by SD.

Seismic performance of polymer modified concretes in flexure-modelling

Considerable research has been carried out in the recent years in the development of models to simulate the inelastic responses of reinforced concrete elements. The enhancement of ductility and the post-peak behaviour are of special interest for the seismic design of structures. Polymer modified fibre concretes are found to be ideal for seismic application with its inherent structural characteristics. An experimental investigation has been undertaken to understand the flexural behaviour of the polymer-modified fibre concrete modified with natural rubber latex. The results are compared with the response of normal strength concrete beam. Analytical modelling of the beams were carried out in a user friendly finite element software to accurately predict the monotonic behaviour of the beams which is considered to be the envelope of cyclic curve. The strains developed were found and are compared with the theoretical results.

Mechanical properties of polymer-modified concretes containing expanded polystyrene beads

In this study, styrene-butadiene rubber (SBR) latex as a polymeric admixture was applied in lightweight expanded polystyrene (EPS) concrete. The effects of curing conditions and polymer-cement ratio on the compressive and flexural strengths of polymer-modified EPS concretes were investigated. As a result, the strength development of the polymer-modified EPS concretes strongly depends on the curing conditions. Combined dry and wet curings enable to develop both the strengths of cement matrix and SBR films together. Inclusion of SBR latex at a certain polymer-cement ratio in the EPS concrete improves the bonds between the cement matrix and EPS particles due to the SBR films formed in the cement matrix. In addition, SBR modification can significantly improve the flexural strength of the normal EPS concrete. Compared with the EPS concrete, the compressive strength of the polymer-modified EPS concretes can increase gradually even after 28 days.

오토클래이브양생에 의한 시멘트 혼화용 폴리머의 내구성

The purpose of this study is to make clear the durability of the polymer films formed in the autoclaved polymer-modified mortars and concretes. The polymer films prepared with polymer dispersions such as a styrene-butadiene rubber (SBR) latex, a poly (ethylene-vinyl acetate)(EVA) emulsion and a polyacrylic ester (PAE) emulsion for polymeric admixtures are exposed to autoclaving at 18 in temperature and 1.01 MPa in vapor pressure, and subjected to tensile test and infrared spectroscopy. The durability of the polymer films is evaluated from the application of autoclaving to the polymer films under saturated Ca(OH) solution immersion causes no degradation for SBR films and a significant degradation due to the saponification of the polymers for EVA and PAE films. Accordingly, in the application of autoclaving to polymer-modified mortars and concretes, it is suggested that SBR-modified mortars and concretes are hardly degraded but EVA- and PAE-modified mortars and concretes are markedly degraded by the saponification of the polymers.

Fracture toughness of polymer-modified asphalt concrete at low temperatures

The fracture toughness of asphalt concrete increases at low temperature and then decreases at temperatures below a certain level. Some polymers are known to have the property of improving the temperature susceptibility of asphalt binder at low temperatures. Therefore, this study evaluated the fracture toughness (KIC) of some polymer-modified asphalt concretes. Low-density polyethylene (LDPE), styrene–butadiene–styrene (SBS), and a mixed polymer of LDPE and SBS were used in this study. The fracture toughness KIC of normal asphalt concrete was compared with that of polymer-modified asphalt (PMA) concrete, and the effectiveness of polymer modification against falling values of KIC was evaluated at low temperatures. The results showed that PMA concretes, in general, showed better KIC than normal asphalt concretes, and the temperature at which the highest KIC was obtained was lower than that in the case of normal asphalt concrete. Therefore, the PMA concretes evaluated in this study had better fracture resistance than normal asphalt at low temperatures.Key words: asphalt concrete, polymer-modified asphalt, PMA, fracture toughness, differential thermal contraction, low-temperature damage.

고로슬래그 미분말을 이용한 SBR혼입 폴리머 시멘트 콘크리트의 강도특성

The effects of slag content and polymer-binder ratio on the strength properties of the polymer-modified concretes using ground granulated blast-furnace slag and a styrene-butadiene rubber (SBR) latex are examined. As a result, the compressive, tensile and flexural strengths of the SBR-modified concretes using slag increase with increasing polymer-binder ratio and slag content, and maximized at a slag content of 40 ％. In particular, the SBR-modified concretes with a slag content of 40 ％ provide approximately two times higher tensile and flexural strengths than unmodified concretes. Such high strength development is attributed to the high tensile strength of SBR polymer and the improved bond between cement hydrates and aggregates because of the addition of SBR latex.

Fatigue behavior of polymer-modified porous concretes

Highly permeable materials provide drainage and noise-absorption properties that are useful in pavement top layers. In such porous concretes, the voids reduce the mechanical integrity, which may have to be compensated for with the incorporation of nonconventional components, such as polymers. A basic property needed for the design of pavements is the fatigue behavior of the material, which has not been studied thoroughly for polymer-modified porous concretes. This paper presents experimental results of fatigue tests in compression in terms of Wöhler curves for four porous concretes (two of them with polymer). It is seen that the polymer-modified porous concretes exhibit better fatigue behavior than those without polymer. However, the improvement decreases for low values of the stress level, S, and appears to be negligible for the case of traffic loads in main roads or highways (number of load cycles, N > 10 6). Additionally, the deformation and internal temperature evolutions have been monitored, and it is concluded that their trends are similar to those of conventional concrete, with temperature increases significantly higher than in conventional concretes.

超速硬ポリマーセメントコンクリートの調合設計法の提案

In recent years, ultrarapid-hardening polymer-modified cement concretes have been used for the repair works of concrete structures. The purpose of this study is to establish the mix design method for the ultrarapid-hardening polymer-modified cement concretes, and to examine its applicability in the field. The ultrarapid-hardening polymer-modified cement concretes for the laboratory test were prepared with various polymer-cement ratios, unit cement contents, water-cement ratios, sand-aggregate ratios and retardercement ratios, and tested for slump, air content, handling time (which was defined as the elapsed time when the slump decreased to about 2cm) and compressive strength.The conclusions obtained from the test results are summarized as follows:(1) The slump of the ultrarapid-hardening polymer-modified cement concretes with various mix proportions may generally be expressed by the following equation:Sl=Ae-B(Vag+Vc)/Vwwhere Sl is the slump of the ultrarapid-hardening polymer-modified cement concretes, Vag, Vc and Vw are the volumes of aggregate, cement and water per unit volume of the ultrarapid-hardening polymer-modified cement concretes respectively, and A and B are empirical constants.(2) The compressive strength and handling time of ultrarapid-hardening polymer-modified cement concretes with various mix proportions may generally be expressed as a function of “void-cement ratio (α)”, “retarder-cement ratio (β)” and “polymer-cement ratio (γ)” by the following equations:F=J/(Kα·Lβ·Mγ)Ht=S·Tα·Uβ·Vγwhere F and Ht are the handling time and compressive strength of the ultrarapid-hardening polymer-modified cement concretes respectively, α is the void-cement ratio [α=(Vw+Va)/Vc], β is the retarder-cement ratio (β=Vr/Vc), γ is the polymer-cement ratio (γ=Vp/Vc), Va, Vr and Vp are the volumes of air, retarder and polymer per unit volume of the ultrarapid-hardening polymer-modified cement concretes respectively, and J, K, L, M, S, T, U and V are empirical constants.(3) The mix design system for the ultrarapid-hardening polymer-modified cement concretes is proposed by use of the respective equations for slump, handling time and compressive strength predictions.(4) The applicability of the mix design system for the ultrarapid-hardening polymer-modified cement concretes is confirmed in the field.

The influence of polymer latex modifiers on the properties of concrete

The influence of styrene-butadiene rubber (SBR) and acrylic latices on the properties of Portland cement concrete is investigated. Properties of modified concretes are compared with unmodified samples, on the basis of constant water/cement ratio, and on the basis of constant workability. In samples with constant water/cement ratio, reduction of compressive strength in polymer-modified concretes is statistically significant, and some improvements in flexural and tensile strengths are observed. Scanning electron microscopic examination of the SBR latex modified concrete, using a heavy element tagging technique and energy dispersive analysis of X-rays, demonstrates a non-uniform distribution of polymer modifier in the cement matrix at higher concentrations.

The influence of polymer latex modifiers on the properties of concrete

The influence of styrene-butadiene rubber ( sbr) and acrylic latices on the properties of Portland cement concrete is investigated. Properties of modified concretes are compared with unmodified samples, on the basis of constant water cement ratio, and on the basis of constant workability. In samples with constant water cement ratio, reduction of compressive strength in polymer-modified concretes is statistically significant, and some improvements in flexural and tensile strengths are observed. Scanning electron microscopic examination of the sbr latex modified concrete, using a heavy element tagging technique and energy dispersive analysis of X-rays, demonstrates a non-uniform distribution of polymer modifier in the cement matrix at higher concentrations.

Discussion: An assessment of the commercial prospects for fibre- and polymer-modified concretes

Discussion: An assessment of the commercial prospects for fibre- and polymer-modified concretes

An assessment of the commercial prospects for fibre- and polymer-modified concretes

Synopsis The principal effects of fibres of various types and of polymers upon the properties of Portland cement pastes, mortars and concretes are discussed briefly, and possible applications are suggested in which the special properties of the modified cement-based materials may be exploited commercially. It is concluded that structural reinforced and prestressed concretes are unlikely to be replaced by fibre or polymer concretes. It is more likely that the viable applications will exploit properties, in either the fresh or the hardened states, that are peculiar to the particular fibres or polymers incorporated in the matrix. It is also suggested that sufficient research has already been undertaken to provide data on the effects of fibres and polymers upon concrete properties and that the major effort should now be directed to the development of saleable products rather than the acquisition of additional basic information.

Elastic Behavior of Polymer-Impregnated Porous Ceramics

The effect of polymer impregnation on the elastic behavior of porous ceramics was investigated. Large increases in the Young's, shear, and bulk moduli and Poisson's ratio were observed. On the basis of a two-dimensional model containing elliptical inclusions, it was shown that the primary role of the polymer on impregnation is to significantly offset the original reduction in elastic moduli caused by the pore phase. The relative effect of polymer impregnation on elastic behavior increases with increasing pore volume fraction and pore ellipticity. These conclusions are also expected to explain the elastic behavior of polymer-modified cements and concretes.