Advanced Materials Research Vol. 1129

Abstract: Sustainability is important in all engineering decisions. Every technical organization now has the objective to promote sustainability. Polymer concrete (PC), in order to have a rightful place in industry, must be sustainable. Based on several criteria, it can be shown that PC materials and products are sustainable. PC applications to be discussed include repair, concrete overlays, and precast products. When designed and constructed appropriately, PC materials and products are sustainable.

Abstract: This paper presents a series of experimental studies on the behaviour of engineered cementitious composites (ECC) under quasi-static and high strain rate loads. Potential enhancement of ECC to the resistance and ductility of structural members was evaluated under column removal scenarios and impact loading conditions. Besides, dynamic increase factors for compressive strength and critical strain were derived according to experimental results under high strain rates. Finally, conclusions and recommendations were made in accordance with the use of these materials for different structural performances.

Abstract: The study of microstructure formation in polymer-cement concrete provides opportunities to exploit synergetic actions between cement and polymer, leading to performance improvement and to a wide range of new and innovative properties and applications. Polymers can reduce the impact of construction industry on environment, by decreasing the carbon footprint of cement production. Renovation and restoration, largely figuring in the concept of sustainable construction development, thank their growing share in construction activity to the input of polymers in repair materials and in rehabilitation procedures. The study of ancient binders and mortars reveals aspects of the origins of the observed long lasting durability of those ancient mortars.

Abstract: Adhesion in this system is one of the most important factors that affect the reliability and durability of repair. According to the many standards and guidelines, e.g. new European Standard EN 1504-10 and ACI Concrete Repair Manual, a pull-off test is recommended for assessment of a bond quality in repair systems. The use of pull-off test, due to its semi-destructive character, is restricted by owners and managers. Therefore, the elaboration of reliable nondestructive method for an adhesion mapping could provide a quite advantageous alternative. Repair system is difficult to test with NDT methods, because of the many factors influencing the stress wave propagation. In this paper the possibility of application of various NDT methods for quality control of repair efficiency, including estimation of the bond strength, is discussed.

Abstract: This paper reports a study on novel geopolymers, focusing on chemically bonded composites, by incorporating wollastonite and recycled mixed plastics. Magnesium oxide and monopotassium phosphate were used as binders; while the recycled mixed plastics consisted of high-density polyethylene and polystyrene at different volume ratios. The effects of molar ratio (magnesium-to-phosphorus ratio), wollastonite-to-binder ratio and recycled mixed plastics content were investigated. The performance of geopolymers was evaluated based on their setting time and water absorption, compressive and flexural strengths as well as thermal properties.

Abstract: Decades ago, an implantation of polymer into concrete has taken an effect in Concrete Polymer Composites, C-PC – new concrete classes and since that time a constant development polymers in concrete technology has been observed. The object of the study in short definition has been described and classified. The meaning of polymer better concrete as well as how polymer improves the concrete has been explained. It has been analyzed and stressed that the polymer function in concrete is much higher than one could deduct from their mass share. The reason for that is synergy effect – the result of cooperation of polymers with other components of concrete. The recognition and using of synergic effects is the main but not only one direction of research works. The polymer in concrete product to be attractive on the market should fit up away growing demands of application and be based on the current status of knowledge. It means persistent and online resolving Material Model – Performance Model relation. Long time study on the modelling of cement hydration and polymer hardening process in Polymer Cement Concrete proved how significant is the idea/theory in technology development. Currently great expectation has been demonstrated towards Water-Soluble Polymers, WSP as nanomodifier of great potentiality. Various types of polymers in various amounts can be used for C-PC; even the polymer of the same type can be differentiated by the structure of polymer chain (length, branching) – this creates almost unlimited area of the control performance of C-PC. Outcome of the past ASPIC and ICPIC Congresses confirms that the research efforts have been always oriented on the engineering results based on the material microstructure understanding. The role of polymers in concrete could be not overestimated.

Abstract: Concrete-polymer composites (CPC) pose a major concern of construction industry in recent years. The use of polymer in concrete has long been proven successful due to its good compatibility and the improvement it makes to the concrete. This overview summarizes status of research and applications of CPC in China within the past 3 years, i.e. the influence of polymer on early hydration of cement, the interaction between polymer and cement, and the applications of CPC in waterproofing materials, pavement, repairing materials and so on.

Abstract: Deep beams, corbels, stepped beams, beams with openings and the like are structural members comprising discontinuous regions for which conventional flexural theory does not apply. To strengthen such members using fibre-reinforced polymer (FRP) systems, a rational approach based on strut-and-tie models (STMs) is desirable. This involves the strengthening of struts, ties and nodal zones where required. This study was carried out to illustrate the use of strut-and-tie models in FRP strengthening of reinforced concrete T-beams with a large opening created through the web. Five 3-meter long simply-supported beams were fabricated to simulate existing beams with webs punctured by openings of lengths varying from 180 to 720 mm and located at about 0.5 to 1.5 m from the near support. The depth of the opening was kept constant at 180 mm. Based on strut-and-tie modelling, the beams were strengthened using glass FRP sheets to carry the same ultimate load as a solid beam which had the same dimensions and internal steel reinforcement but without opening, that is, 200 kN. The beams were each subjected to a single load at one-third span from the other support. Test results indicated that all beams with strengthened opening performed as well as the solid beam without opening in terms of cracking and deflection characteristics, in addition to ultimate strength and ductility.

Abstract: Functional, high performance mortars such as Self-Leveling Underlayments (SLU), Tile Adhesives (TA) or Grouting Mortars (GM) are composed, besides complex binders, of mineral and organic fillers, and most importantly admixtures. Amongst the organic fillers, re-dispersible powders produced by spray drying from emulsions, are added to improve flexibility, adhesion and water resistance. These powders, however, also influence fresh properties such as workability and plastic shrinkage or sedimentation. Additionally they are prone to interfere with the hydration kinetics thus playing a role in the very early structuring process of a cement-based mortar.In this study, the influence of re-dispersible powders on sedimentation, plastic as well as chemical shrinkage in ternary binder composites has been investigated for the first 24 hours. The structuring process has been additionally characterized by the hydrate phase development. Ternary binders are defined in this study as compositions of Calcium Aluminate Cement (CAC), Ordinary Portland Cement (OPC) and Calcium Sulfate (CS̅).The addition of re-dispersible powders showed not only the well-known retardation in hydration kinetics, longer setting times and increased gel times but also changed dimensional stability. Dimensional changes occurring during the first 24 hours were monitored by different test devices in order to separate different shrinkage/expansion mechanisms. The measurements are compared to the in-situ measurement of phase development by XRD.