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Iron tailings are mineral wastes obtained from industrial processing and magnetic separation of iron ore. Foam concrete with iron tailings can be made with iron tailings, cement, fly ash, silica fume, polypropylene fiber, superplasticizer, early strength agent, accelerating agent and foaming agent. The influences of polypropylene fiber on the crack resistance and frost resistance of foam concrete have been investigated in this study. Further, the microstructure of foam concrete was observed. This result demonstrates that polypropylene fiber has greatly increased the crack resistance and frost resistance of foam concrete. The pore structure of foam concrete is improved obviously by polypropylene fiber. Due to the uniformly distributed pores, high porosity and rather complete pore wall, the mechanical properties and thermal properties of foam concrete are excellent. The foam concrete with high-strength and excellent thermal insulation property develops a new route for the comprehensive utilization of iron tailings.

Iron tailings are mineral wastes obtained from industrial processing and magnetic separation of iron ore. A type of superplasticizer with high water reducing rate and early strength gaining property is characterized in this study. The influence of admixtures, i.e. superplasticizer, early strength agent and accelerating agent, on the mechanical strength, setting and hardening time of foam concrete containing iron tailings has been investigated. Further, the microstructure of foam concrete is observed. This study demonstrates high-strength foam concrete with excellent thermal insulation property can be prepared using iron tailings, cement, fly ash, silica fume, polypropylene fiber, superplasticizer, early strength agent, accelerating agent and foaming agent, which develops a new route for the comprehensive utilization of iron tailings.

The thermal insulation mortar with cinders and phase change materials which is made from expanded perlites adsorbing composite phase change material, cinders and vitrified small ball as lightweight aggregate has the characteristics of both energy storage and thermal insulation. In this paper,we studied the effect of redispersible emulsion powder, methyl cellulose ether, organic fiber and water-reducing agent on the performance of thermal insulation mortar with cinders and phase change materials. The result showed that all the performance met the national standards of the thermal insulation mortar.

In this study, a kind of water reducing agent based on Isoamyl enol polyoxyethylene ether were synthesized in water solution by radical copolymerization. The influence of copolymerization conditions on dispersing performance of the water reducing agent in the cement was investigated. The molecular structure of the copolymer was tested by NMR, and GPC was used to determine the molecular weight of copolymer and the big monomer percent conversion, also, testing the adaptability of the water reducing agent in different types of cement. The testing results show that the water reducing agent has the good performance on concrete. When the dosage of water reducing agent was 0.2%, the (Deer ding card, P.O42.5) slurry flow degree of the cement was 270mm, and the water reducing ratio reached 19.6%. When the dosage of water reducing agent was 0.3% and 0.4%, the water reducing ratio reached to 28.6% and 31.9% respectively. Comparing the adaptability of the water reducing agent on all kinds of cement, the water reducing agent performed the worst in the P.C cement and better in the P.O cement, its adaptability in the standard cement and P.S cement was the best. When the dosage of water reducing agent was 0.2%-0.4%, the water reducing ratio was nearly the same, When the dosage of water reducing agent was 0.4%-0.6%, the water reducing ratio in the standard cement was higher than in the P.S cement.

Iron tailing is a kind of mineral waste from industrial processing and magnetic separation of iron ore, which severely pollute the air, soil property and the source of water. For large scale tailing ponds (dam height >100 m), the accident could cause a substantial damage. Therefore, it is significant to appropriately utilize the tailings. The present paper systematically studies the possibility of complete replacement of quartz sand with the iron tailings in polymer modified cement mortar used in external wall insulation plaster. The effects of redispersible polymer powers, cellulose ether, water reducing agent, lignin and polypropylene fiber on the performance of polymer modified cement mortar have been discussed. The results show that the performance of polymer-modified cement mortar composed of iron tailings has reached the national standard of external wall insulation system in China.

Because the fly ash will produce large amounts of the secondary waste emission after the extraction of aluminum, the utilization of the fly ash residue after the extraction of aluminum has great significance. The autoclaved fly ash bricks studied in this paper use CFB ash residue after extraction of aluminum as the main material, and calcium carbide clay which consists mainly of calcium hydroxide is the waste residua of the production of acetylene gas in the chemical plants. This paper analyzes the chemical composition, the mineral composition and the microstructure of the fly ash residue after extraction of aluminum. In the paper, we also study the law and impacts of compressive strength, flexural strength, frost resistance and water absorption, which are made by calcium carbide clay for the autoclaved fly ash bricks. Experimental results illustrate that calcium carbide clay can significantly improve the compressive strength, the flexural strength and the frost resistance of the coal fly ash autoclaved bricks, and significantly reduce its water absorption.

Abstract:We test hypotheses that can account for the variation in seed size in a database of 229 species from a subalpine meadow on the east part of the Tibetan plateau. Information on seed mass, plant height, dispersal mode, onset of flowering, and family membership is included. We use general linear models to consider not only the primary correlations between seed size and each variable, but also overlap patterns among correlations to determine whether particular relationships arise as a result of indirect correlations through other variables. The strongest association of seed size is with family membership, and the variation accounted for by family membership overlaps with that accounted for by plant height, dispersal mode, and onset of flowering. Similarly, we find that there are overlaps in the seed-size variation explained both by plant height and dispersal mode and by plant height and onset of flowering. However, there is no association in the variation in seed size accounted for by plant height and onset of flowering. Family membership, plant height, dispersal mode, and onset of flowering have significant associations with seed size independently of the other variables measured. We cannot give a logical explanation for the relationship between seed size and onset of flowering.