Study on the geopolymers has been a history of nearly 40 years, because of its huge comparative advantage and attractive prospect, has become a hot research field of international materials.In this paper, based on the history and the present status of geopolymers cementitious materials development, summarized geopolymer cementitious material in the selection of raw materials, the activation agent development,preparation process research, cementitious material properties, mechanical properties, durability and engineering applications. progress made and trends.On this basis, expounded the problem of large-scale widely used the geopolymers need to continue to address, and pointed out the direction for its further research and application.
Seawater and sea sand mixed in concrete will cause rebar of structural concrete corrosion, referring to the principles of composition and design of MCI and Pearson’s Hard-Soft Acid-Base (HSAB) theory, as well as to synergy effect of corrosion inhibitor applied in chemical industry, compound corrosion inhibitor has been designed consisting of diisopropanolamine, surface active agent, inorganic salts and so on. This paper research the relation between polarization potential and time of rebar in seawater-and-sea sand concrete through a series of experiments by adding corrosion inhibitor into seawater-and-sea sand concrete to improve its corrosive resistance characteristics. The results indicate that Z5 has the best inhibition effect. Corrosion inhibitor Z5 comprises 50% of triethanolamine, 20% of dimethylethanolamine (DMEA), 25% of triethoxysilane and 5%lithium nitrate, and its proper content applied in seawater-and-sea sand concrete is 1.5%. Rebar have been embedded in seawater-and-sea sand concrete for the long-term test. The results show that corrosion resistance performance of seawater-and-sea sand concrete with corrosion inhibitor Z5 was significantly improved, and the embedded bar was not corroded at all within 420 days.
The modification effects of the cement and the water-based epoxy resin on the asphalt emulsified mortar are studied. The result shows that with the cement content 30% and water-epoxy resin emulsified content 30%, the modified asphalt emulsified mortar which can replace cement mortar meets the demands of the relative criterions. When the temperature reaches 140°C, both the tensile bond strength and the shear bond strength decrease to 0.1 MPa. So it is feasible to recycle the decorative stone .The micro-analysis of the modified mortar are investigated by using IR and TGA-DTA, and its modification mechanism is also discussed.
As a new type of building material, Basalt Fiber Reinforced Plastics is employed in concrete in place of steel reinforcement under such strongly-corrosive environment as marine engineering projects to avoid durability problem caused by corrosion. But BFRP bars’ alkali-resistance must be considered and studied. In this study, BFRP was soaked in saturated Ca(OH)2 solution and its tensile strength was measured through long-period immersion and high-temperature immersion experiments respectively. Besides, accelerated high-temperature method was adopted to detect its main ingredients: continuous Basalt fiber and resin. The results indicate that BFRP has poor alkali-resistance and its alkali-resistance must be improved if it is applied in concrete for long-term purpose.
It is inevitable for steel reinforcement to be corroded when mixed with seawater-and-seasand concrete. In order to improve steel corrosion protection properties of seawater-and-seasand concrete, reduce the chloride ion’s attack on steel reinforcement in structural concrete and lengthen the steel reinforcement’s service time, this paper presents an experimental study on whether admixtures like fly ash, slag and metakaolin in the seawater-and-seasand could retard the corrosion to steel reinforcement and provide protection to steel reinforcement in seawater-and-seasand concrete. The results indicated that metakaolin had a significant anti-corrosion effect and greatly enhanced the steel corrosion protection properties of seawater-and-seasand concrete whereas both fly ash and slag did not appear to have any obvious influence on curbing the corrosion of steel reinforcement.
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