LOCALIZED SUPERPLASTIC BEHAVIOUR INα-TITANIUM AT HIGH STRAIN RATE

The microstructure of x-Ti/ mild steel composite fabricated by using constant stand-off cladding technique was observed with optical microscopy, SEM and TEM analyses. Very fine equiaxed grains (<0.1um) with a low dislocation density were observed in the adiabatic shear bands (ASB) this enables a thermomechanical response that may lead to a super plastic de formation.

Synthesis of Super Plasticizer NF-30 from Coal Coking by Product Washing Oil and Performance Analysis

Super plasticizer was synthesized by using coal coking by product washing oil and industrial naphthalene. The results show that sulfonationt time （2.5 h）, sulfonation temperature （160 ℃） and condensation time （5.0 h） are key factors. Adding oxidizing agent MO in the course of synthesis can decrease the emission of SO2 in exhaust （20%）. Compared with NF, NF-30 have some advantages in lower cost, high water reducing rate （19.7%） and optimum early strengths. Moreover, TGA-DTA and SEM analysis were adopted to research the NF-30 modified concrete on hydyation mechanism. The analysis show that, compared with NF, there are a large number of hydration products such as Ca （OH）2, C-S-H, AFt etc of NF-30, the structure of NF-30 is dense and the performance is good.

Underground void filling by cemented mill tailings

Underground mining always create voids.These voids can cause subsidence of surface.So it is always a demand to fill the void in such a manner that the effect of underground mining can be minimized.Void filling using mill tailings especially in metal mining is one of the best techniques.The tailings produced in milling process have traditionally been disposed in tailing ponds creating a waste disposal and environmental problems in terms of land degradation,air and water pollution,etc.This disposal practice is more acute in the metal milling industry where the fine grinding,required for value liberation,results in the production of very fine tailings in large percentage.This paper includes discussions on the effectiveness of different paste mixes with varying cement contents in paste backfilling operations.The results revealed that material composition and use of super plasticizer strongly influenced the strength of cemented backfill.

MECHANICAL PROPERTIES AND MICROSTRUCTURE OF COMPOSITE BINDERS CONTAINING SHALE ASH AND FLY ASH

The microstructure and the mechanical properties of hardened mortars made of superplasticized composite binder containing shale ash and fly ash are investigated. The pozzolanic reaction consumes the oriented Ca (OH)//2 crystals, thus making the transition zone dense. Appropriately proportioning of shale ash and fly ash decreases the water requirement and increases the packing density of composite binder mortars, therefore increases their strength. Superplasticizer promotes the carbonation of calcium hydrates and the formation of ettringite that is transformed gradually into mono-sulfoaluminate hydrate in composite binder mortars. The joint action of fine complex mineral admixture and superplasticizer has a synergistic effect to improve the mechanical properties of composite binder. (Author abstract) 7 Refs.

Effect of polycarboxylate type of super plasticizer on the hydration properties of composite cements

The work aims to study the effect of polycarboxylate type of super plasticizer on the hydration of composite cements.In this paper we have studied the hydration of 20 wt%fly ash(FA)blended Portland cement in the presence of 0.1 wt%super plasticizer(SP).Water consistency,setting times,non-evaporable water contents,compressive strength,water percolation,and air content measurements were carried out.In addition,Xray diffraction studies were carried out to understand the hydration process.The results indicated the increase in compressive strength of the FA blended Portland cement in the presence of SP and with the increase of the hydration time.