Durability Of Cement-based Composites Research Articles

Preparation and properties of pretreated jute fiber cement-based composites

In order to resolve the contradiction of poor compatibility between plant fiber and cement-based materials and improve the toughness and durability of cement-based composites, this paper takes jute fiber cement-based composites as the research object, and proposes the pretreatment method of jute fiber through mass loss rate and water absorption test. The influence of pretreated jute fiber on the properties of cement-based composites was investigated by means of mechanical properties and frost resistance tests. The strengthening mechanism of jute fiber in the pre-treatment of cement-based composite materials was revealed from a microscopic perspective using scanning electron microscopy and mercury porosimetry. The results indicate that the quality loss rate of jute fiber soaked in hot alkali solution ( 60 ℃, 4% NaOH solution) was the largest, which was 37.94%. After dipping in 10% chloroprene latex, the fiber water absorption was the smallest, which was 0.93%. Therefore, the jute fiber was pretreated by the combination of hot alkali solution soaking and chloroprene latex impregnation. The pretreatment of fibers will reduce the fluidity of the composites, but has little influence on the setting time of the composites. The flexural strength, splitting tensile strength, dry shrinkage and frost resistance of the composites are significantly improved by the pretreatment fiber, but the compressive strength is slightly insufficient. The jute fiber after pretreatment can achieve reinforcement, crack resistance and toughening, reduce the porosity of cement-based composites, and optimize the pore structure inside the cement-based composites.

Research progress on properties of cement-based composites incorporating graphene oxide

Abstract Graphene oxide (GO) is a two-dimensional derivative of graphene material, with carboxy, hydroxy group functional groups at the middle of the sheets, and oxygen-containing functional groups at sheet edges. It has multiple advantages, such as high strength, hydrophilicity, and strong reactivity. With the development of construction materials, GO has been widely used as a nano-reinforced material in cement-based composites (CBCs). Based on a large amount of relevant literature, the preparation and dispersion behavior of GO-reinforced CBC are summarized. Besides, the impact of GO on the workability, volume stability, mechanical performance, and durability of CBC are discussed. Moreover, the influencing mechanism of GO on the hydration of CBC is expounded. From the findings of this review, the following conclusions can be drawn: the fluidity of CBC will be decreased when GO is evenly dispersed in the cement slurry, which results in a loss of workability of CBC. Meanwhile, the addition of GO improves the volume stability of CBC, while the tensile, compressive, and flexural strengths are all improved to varying degrees. The improvement of GO on the durability of CBC is mainly reflected in the corrosion resistance and permeability resistance. In addition, problems existing in the current research are summarized and future perspectives are put forward. The review work in this article could offer important guidance for further research and implementation of GO-doped CBC in practical engineering.

Effect of Surface Penetrating Sealer on the Microstructure Properties of Cement-Based Composites

The effect of penetrating sealer on the structure of surface pore, mechanical properties, and durability of cement-based composites was studied. Concrete specimens with various water/cement ratios (w/c=0.35, 0.45, 0.55) were cast and treated surfaced with various amounts of penetrating sealer at different ages. The effect of penetrating sealer on the mechanical properties of concrete was assessed by compressive strength. And, the rapid chloride permeability was also explored to test concrete durability. Test results indicate that the application of penetrating sealer significantly improves concrete compressive strength and chloride resistance. By using scanning electron microscopes observation, the penetrating depth of penetrating sealer can be determined and is about 2 cm. The penetrating sealer in this study may be categorized as deep penetrating sealer.

Quantitative evaluation of mineral admixtures on the properties, pore structure, and durability of cement-based composites

AbstractThe influence of water/cementitious material ratio, silica fume, and fly ash as partial Portland cement replacement materials on the properties, pore structure, and durability of cement-based composites was evaluated by conducting compressive strength test, mercury intrusion porosimetry test, water absorption, rapid chloride penetration test, and scanning electron microscopy (SEM). Water/cementitious material ratio, and replacement percentage of silica fume and fly ash have significant effects on the pore structure and durability of cement-based composites. Composites with silica fume or fly ash have a denser structure than the control composite on SEM micrographs. Silica fume has about 5–10 times as much effect as fly ash, according to results of multiple linear regression analyses of testing data.

Effect of Microstructure on Durability of Cement-Based Composites by Accelerating Calcium Leaching Test

Effect of Microstructure on Durability of Cement-Based Composites by Accelerating Calcium Leaching Test

Calculation of the coefficients of oxygen permeability of mortar samples using PORECOR analysis

It has been established that the durability of cement-based composites is generally controlled by the transport characteristics of fluid in their pore network. Experience has shown that the monitoring of transport properties, such as the coefficient of permeability, in the laboratory is a very exhaustive task. The pore network in a cementitious composite, which provides passage for fluid transportation, is a major controlling factor for transport characteristics. In the last few years, many efforts have been made to correlate the microstructure and the coefficient of fluid permeability, and/or diffusion, for a cementitious composite. In this study, a set of ordinary Portland cement (OPC) and OPC/fly ash mortar samples equilibrated in different relative humidity were analysed using PORECOR analysis and the coefficient of oxygen permeability was calculated and compared with the coefficient of permeability of another set of the same samples tested in the laboratory, and valid statistical correlation was obta...