Experimental data on the properties of polymer-modified cement grouts using epoxy and acrylic resin emulsions

AbstractThe use of additives to improve the quality of cement grouts is crucial for civil engineering, especially in foundation construction. This article presents experimental data concerning the compressive strength, elastic modulus, bleeding and injectability of microfine cement grouts modified with epoxy and acrylic resin emulsions. Strength properties were obtained at different curing ages. For further analysis and detailed discussion of properties of polymer-modified cement grouts, see “Fundamental properties of epoxy resin-modified cement grouts” (C.A. Anagnostopoulos, G. Sapidis, E. Papastergiadis, 2016) [1]

Graphene and related materials in hierarchical fiber composites: Production techniques and key industrial benefits

Fiber-reinforced composites (FRC) are nowadays one of the most widely used class of high-tech materials. In particular, sporting goods, cars and the wings and fuselages of airplanes are made of carbon fiber reinforced composites (CFRC). CFRC are mature commercial products, but are still challenging materials. Their mechanical and electrical properties are very good along the fiber axis, but can be very poor perpendicular to it; interfacial interactions have to be tailored for specific applications to avoid crack propagation– and delamination; fiber production includes high-temperature treatments of adverse environmental impact, leading to high costs. Recent research work shows that the performance of CFRC can be improved by addition of graphene or related 2-dimensional materials (GRM). Graphene is a promising additive for CFRC because: 1) Its all-carbon aromatic structure is similar to the one of carbon fiber (CF). 2) Its 2-dimensional shape, high aspect ratio, high flexibility and mechanical strength allow it to be used as a coating on the surface of fiber, or as a mechanical/electrical connection between different fiber layers. 3) Its tunable surface chemistry allows its interaction to be enhanced with either the fiber or the polymer matrix used in the composite and 4) in contrast to carbon fibers or nanotubes, it is easily produced on a large scale at room temperature, without metal catalysts. Here, we summarize the key strategic advantages that could be obtained in this way, and some of the recent results that have been obtained in this field within the Graphene Flagship project and worldwide

Study on High Performance Polymer-Modified Cement Grouts

Engineers worldwide use various additives or chemical admixtures, such as polymer latexes, to improve the properties of cementitious materials for many construction projects. In this paper, the influence of acrylic or epoxy resin emulsions, along with a polycarboxylate superplasticiser on some basic properties (rheological behaviour, setting time, bleeding, strength) of thick cement grouts is presented. The experimental approach included the use of different polymer dosages mixed with grouts made of low water to cement ratios. The laboratory tests revealed that the incorporation of acrylic resin in grouts marginally affected the viscosity, whereas a significant increase in viscosity was obtained when an epoxy resin was added. Regardless of the prolonged setting times, both polymers improved the development of early or final strength. An acrylic resin dosage ranging from 0.25% to 0.75% and an epoxy resin dosage from 5% to 7.5% displayed the highest strength values, at all water to cement ratios. Additionally, all the polymer-modified grouts exhibited a higher bleed capacity, a fact that is significantly important where the bleeding of the grouts is crucial

The Inclusion of Acidic and Stormwater Flows in Concrete Sewer Corrosion Mitigation Studies

Concrete sewer pipes can be deteriorated by sulfuric acid (H2SO4), which is created by the oxidation of hydrogen sulfide in the presence of certain bacteria inside the sewers. This process is called biocorrosion. In this paper, H2SO4 (i.e., chemical, non-biogenic) was used to study acid attack on concrete samples. The authors conducted experiments under different acid flows and concentrations, to account for the conditions prevailing in sewage networks exposed to flowing acidic waters. The effect of intermittent stormwater on the removal of protective layers was studied in addition to constant flow runs. Specimens’ erosion depth was measured with a Vernier micrometer. In addition, unconfined compression at an axial strain rate of 0.0016 mm/mm/min was used for the estimation of unconfined compressive strength and elastic modulus. Moreover, the formation of gypsum as a protective layer and its role in biocorrosion was discussed. From this study, it was concluded that although the utilization of constant flowrates of acidic waters represents an important indication of corrosion mechanism, intermittent sewage and water flows should be taken into account, corresponding to real conditions in sewage networks, and resulting into accelerated concrete corrosion. Stormwater in combined sewers could remove the protective gypsum layer, thus accelerating chemical corrosion; however, in the presence of biogenic H2SO4, the removal of gypsum by excess flows due to stormwater could have a positive effect on corrosion mitigation. Finally, for combined sewers, selected coatings should withstand the effect of stormwater and high-velocity water flow tests should be included in future studies

The Inclusion of Acidic and Stormwater Flows in Concrete Sewer Corrosion Mitigation Studies

Concrete sewer pipes can be deteriorated by sulfuric acid (H2SO4), which is created by the oxidation of hydrogen sulfide in the presence of certain bacteria inside the sewers. This process is called biocorrosion. In this paper, H2SO4 (i.e., chemical, non-biogenic) was used to study acid attack on concrete samples. The authors conducted experiments under different acid flows and concentrations, to account for the conditions prevailing in sewage networks exposed to flowing acidic waters. The effect of intermittent stormwater on the removal of protective layers was studied in addition to constant flow runs. Specimens’ erosion depth was measured with a Vernier micrometer. In addition, unconfined compression at an axial strain rate of 0.0016 mm/mm/min was used for the estimation of unconfined compressive strength and elastic modulus. Moreover, the formation of gypsum as a protective layer and its role in biocorrosion was discussed. From this study, it was concluded that although the utilization of constant flowrates of acidic waters represents an important indication of corrosion mechanism, intermittent sewage and water flows should be taken into account, corresponding to real conditions in sewage networks, and resulting into accelerated concrete corrosion. Stormwater in combined sewers could remove the protective gypsum layer, thus accelerating chemical corrosion; however, in the presence of biogenic H2SO4, the removal of gypsum by excess flows due to stormwater could have a positive effect on corrosion mitigation. Finally, for combined sewers, selected coatings should withstand the effect of stormwater and high-velocity water flow tests should be included in future studies

Primary treatment of low-grade non-Hodgkin's lymphoma with the combination of fludarabine and mitoxantrone: a phase II study of the Hellenic Cooperative Oncology Group

The treatment of patients with recurrent low-grade lymphoma with the combination of fludarabine, mitoxantrone and dexamethasone has been associated with significant activity but has also caused frequent infectious complications. We designed a phase 11 study for previously untreated patients with the combination of fludarabine and mitoxantrone but without steroids. Our aim was to assess the activity of this combination as primary treatment for low-grade lymphoma and to avoid the additional immunosuppression induced by dexamethasone. Twenty seven patients with low-grade lymphoma received fludarabine 25 mg/m(2)/day IV on days 1 - 3 and mitoxantrone 10 mg/m(2) IV on day 1. The treatment was repeated every 28 days for a maximum of six cycles. Twenty patients (74%) achieved an objective response including 12(44%) complete and 8(30%) partial responses. The main toxicity was grade III or IV neutropenia, which occurred in 40% of patients but there were no severe opportunistic infections. The median time to progression for all patients was 32 months. With a median follow-up of 33.4 months, six patients have died and the probability of survival at 3 years is 75%. We conclude that the fludarabine and mitoxantrone regimen is safe and effective for newly diagnosed patients with low-grade lymphoma who require treatment. Prospective randomized trials are needed in order to assess the impact of this treatment on patients’ survival

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