This paper reports a comparative study on the tribological characteristics of base oils in four groups, synthetic esters, mineral oils, polymerized alpha olefins (PAOs), and poly alkylene glycols (PAGs), by means of viscosity, friction, and wear measurements. Friction coefficients for the lubricants in each group, measured with a pin-on-disk tribometer, are summarized in the form of Stribeck curves. Wear of the disk specimens due to rubbing in the interfaces lubricated with the tested oils is evaluated by surface topographic changes. The results indicate that for surfaces of similar roughness, viscosity has the predominant influences on the friction and wear-protection properties of these lubricants.

Redispersible polymer powder of vinyl acetate and versatate copolymer (VA/Voeva) used as admixture additive, is introduced to modify lightweight cement mortar with ground granulated blast furnace slag, quartz sand and expanded perlite as aggregates. The effect of the dosage of redispersible polymer powder of vinyl acetate and versatate on the compressive and flexural strengths was investigated in details. The ratio of compressive strength to flexural strength (σc/σf ) of cement mortars varied with the variation of the dosage of redispersible polymer powder. Scanning electronic microscopy was used to investigate the internal structure of the polymer-modified lightweight cement mortar. The result showed that the toughness of the polymer-modified lightweight cement mortar was improved with the increase in the dosage of redispersible polymer powder, and the network membranous structure formed by the polymer attribute to the improvement of the toughness and flexural strengths.

A new type of lightweight cement mortar was developed by using ground granulated blast furnace slag, quartz sand and expanded perlite as aggregates which were mixed with cement homogeneously. Consistence was used to characterize the workability of lightweight cement mortar. The effect of the components, including the proportions of granulated blast furnace slag and the addition of fly ash, on the properties was investigated in details. The results showed that the values of compressive and flexural strength increased with the ratio of slag to sand. Additionally, the introduction of fly ash improved the consistency and strength properties of lightweight cement mortar.