Analysis of shrinkage and creep behaviors in polymer-coated lightweight concretes (original) (raw)
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Internal structure examination of lightweight concrete produced with polymer-coated pumice aggregate
In the construction sector, pumice is observed to be used in both structural and non-structural building elements. In this study, to produce a new kind of concrete, the aggregates are coated with three different polymers (Sonomeric1: SNMC, KB Pur 214: KBP and Polipol3455: PLP) that have multiple uses. The mineralogical-petrographical features of both polymer-coated and uncoated aggregates were examined, and SEM (Scanning Electron Microscope) and XRD (X-ray Diffraction) analyses were performed. Moreover, in the study, lightweight concrete elements with different dosages (300, 400 and 500) were produced by using polymer-coated and uncoated aggregates; and their internal structure examinations were performed and compressive strength values of 3, 7 and 28 days samples were investigated. As a conclusion; among the aggregate samples, it was determined that PLP-coated aggregates have a more porous structure than the other polymer-coated aggregates and KBP-coated aggregates could be used in lightweight concrete (500 dosage) production. It was also concluded that the compressive strength values of lightweight concrete elements produced with coated samples increased even more.
Effect of polymer content and temperature on mechanical properties of lightweight polymer concrete
2020
This study investigates the mechanical properties of lightweight polymer concrete (LWPC) containing four different polymer ratios (10%, 12%, 14%, and 16%) tested at three different temperatures (−15 °C, +5 °C, and +25 °C) using destructive and non-destructive tests. In addition, a series of expressions are suggested to predict the splitting-tensile, flexural and impact strength of LWPC based on the main parameters and compressive strength. The analysis of variance (ANOVA) method was also used to determine relative contributions of the experimental parameters. The results of the destructive tests show that increasing the polymer ratio caused an increase in the compressive, splitting-tensile, and impact strengths, and energy absorption of LWPC. With decreasing the temperature from +25 °C to −15 °C, the compressive, splitting-tensile, flexural strengths, and elastic modulus (EM) increased, whereas the energy absorption, impact energy, and ductility decreased. The findings of this research provide beneficial information toward understanding the behavior of LWPC and its safe use in engineering applications where a material of high strength-to-weight ratio is required.
Creep and shrinkage of ultra lightweight cement composite
2013
Creep and shrinkage behaviour of an ultra lightweight cement composite (ULCC) up to 450 days was evaluated in comparison with those of a normal weight aggregate concrete (NWAC) and a lightweight aggregate concrete (LWAC) with similar 28-day compressive strength. The ULCC is characterized by low density < 1500 kg/m3 and high compressive strength about 60 MPa. Autogenous shrinkage increased rapidly in the ULCC at early-age and almost 95% occurred prior to the start of creep test at 28 days. Hence, majority of shrinkage of the ULCC during creep test was drying shrinkage. Total shrinkage of the ULCC during the 450-day creep test was the lowest compared to the NWAC and LWAC. However, corresponding total creep in the ULCC was the highest with high proportion attributed to basic creep (≥ ~90%) and limited drying creep. The high creep of the ULCC is likely due to its low E-modulus. Specific creep of the ULCC was similar to that of the NWAC, but more than 80% higher than the LWAC. Creep c...
Bond strength of polymer lightweight aggregate concrete
Polymer Composites, 2013
Bond strength, physical, and mechanical properties of lightweight PC were investigated with inclusion of pumice lightweight aggregate in maximum size of 12 mm. As binder material, epoxy resin-based polymer was used with its hardener. The binder to aggregate ratio was 30% by weight. In addition, steel fibers were added to lightweight PC mixtures in ratio of 0, 0.5, and 1%. After lightweight PC mixture was prepared, it was poured in the molds with different type of steel-bars in size of 100 3 100 3 100 mm 3. The steel-bars centered in the cubic molds, and they were in size of Ø12, Ø14, and Ø16. The specimens were cured at 60 C for 2 h. On the hardened polymer lightweight concrete (PLC), pull-out test for bond strength and compressive strength tests were performed. Moreover, ultrasonic pulse velocity, water absorption by weight, specific porosity, and density experiments were carried out. The relation between physical and mechanical properties showed that PLCs become more durable when using ratio of steel fibers.
Structural Engineering and Mechanics
Creep and shrinkage behaviour of an ultra lightweight cement composite (ULCC) up to 450 days was evaluated in comparison with those of a normal weight aggregate concrete (NWAC) and a lightweight aggregate concrete (LWAC) with similar 28-day compressive strength. The ULCC is characterized by low density < 1500 kg/m 3 and high compressive strength about 60 MPa. Autogenous shrinkage increased rapidly in the ULCC at early-age and almost 95% occurred prior to the start of creep test at 28 days. Hence, majority of shrinkage of the ULCC during creep test was drying shrinkage. Total shrinkage of the ULCC during the 450-day creep test was the lowest compared to the NWAC and LWAC. However, corresponding total creep in the ULCC was the highest with high proportion attributed to basic creep (≥ ~90%) and limited drying creep. The high creep of the ULCC is likely due to its low elastic modulus. Specific creep of the ULCC was similar to that of the NWAC, but more than 80% higher than the LWAC. Creep coefficient of the ULCC was about 47% lower than that of the NWAC but about 18% higher than that of the LWAC. Among five creep models evaluated which tend to overestimate the creep coefficient of the ULCC, EC2 model gives acceptable prediction within +25% deviations. The EC2 model may be used as a first approximate for the creep of ULCC in the designs of steel-concrete composites or sandwich structures in the absence of other relevant creep data.
Effect of Polymer Type and Specimen Size on the Strength of Concrete-Polymer Composite
Journal of Materials and Chemical Engineering, 2014
This paper presents the effect of polymer type and specimen size on the strength properties of concrete-polymer composite. The aim of this study is to determine the compressive strength and the stress-strain behavior of the test samples. Three different types of polymer are used; polypropylene (PP), Low Density Polyethylene (LDPE), and Poly-VinylPyrrolidene (PVP), with different additives to modify the cement concrete matrix. By means of compressing loading method, the compressive strength and stress-strain properties of polymer modified concrete are measured. The effect sample thickness on the mechanical properties is also investigated. The results demonstrated that the polymer-modified concrete, made with a hybrid layer of (PP+PE) shows maximum enhancement in tensile stress and ultimate strain with ratio about 42% , and 33% respectively. The results show that The compressive strengths of polymer concrete composite were not enhanced by the addition of (PVP) fine powder.
Evaluation and nonlinear quantification of early age strength of concrete containing PCE polymer
IOP Conference Series: Materials Science and Engineering, 2020
This research is focused on the impact of three types of polycarboxylate polymer (PCE) on the plastic properties such as setting time of cement and slump of concrete and also, to assess their effects on compressive strength (CS) and concrete density. The percentage of each type of polymer ranged from 0 to 0.25% (by weight of cement). The slump test and CS results of concrete modified with polymers were compared with the silica fume concrete used in the literature. The water to cement ratio (w/c) initially was 0.60 and decreased gradually to 0.46 by increasing the polymer dosage. The CS of concrete modified with 0.25% of polymers increased by 24% and 97% based on the polymer type, polymer content, w/c and curing age. Non-linear regression analysis was used to model the compressive strength of concrete modified with three types of the polymer as a function of polymer content, w/c, and curing time. Based on the literature data and results of this study, it found that the polymers are more effective than silica fume on enhancing the workability and CS of concrete.
Development of an Ultra-Lightweight Thin Film Polymer Modified Concrete Material
Key Engineering Materials, 2011
Certain construction situations call for the use of ultra-lightweight concrete materials. The properties of such materials allow for the utilisation of concrete in weight critical applications, for example precast elements, roofing panels, flooring and cladding of structures. The weight saving benefits of lightweight concrete are evident, yet a trade-off in the strength and durability characteristics of the concrete are made. This paper sets out to develop an ultra-lightweight thin filmed polymer modified concrete material for such applications. This material may incorporate specialised aggregates and admixtures to meet performance requirements but the effects of these on the performance of the lightweight concrete are to be carefully evaluated. This paper presents some of the results obtained by means of laboratory testing as well in-situ testing. As part of the in-situ testing, the paper also reports on the practical evaluation of the ultra-lightweight material characteristics performed through the construction of a light weight concrete racing canoe. This allowed for the evaluation of the material performance characteristics and the establishment of acceptable work and application methods when constructing with this material.
Shrinkage of high performance lightweight concrete exposed to hot-dry weather conditions
MATEC Web of Conferences, 2018
The main aim of this investigation is to study the combined effect of hot-dry weather conditions on the plastic and drying shrinkage of high performance lightweight aggregate concrete (HPLWAC) specimens, along with the other properties including, workability, setting time compressive and splitting strength. The experimental program including the use of fixed mix proportions and was carried out in a typical Iraqi summer day (under actual conditions) of different times during the day. The results indicate that the use of lightweight aggregate play a main role in decreasing the effect of hot dry weather on plastic shrinkage, as well as the plastic shrinkage strain of HPLWC specimens cast at 12:00 pm. less than that of normal weight aggregate concrete specimens by about 36.7%. While drying shrinkage of HPLWC specimens at initial ages up to 7 days was low and it increases with a higher rate at later ages.