In AR-GFRC growth of hydration products around the filaments plays a dominant role in inducing embrittlement of the fibers and loss of toughness of the composites.The purpose of this paper is to present the way to limit the anchorage of the fibers in the matrix and to obtain a long term flexural strength of 30 MPa and an ultimate strain of 0,7 %. The improvement of the matrix is obtained by using selected metakaolinites and acrylic polymers in order to optimize the nature of the hydrates in the interface between the fibers and the matrix.The mecanical properties and durability behaviours are reviewed using three accelerated ageing tests based on warm water, wet-dry cycles and freeze-thaw cycles. The toughness indices proposed by Shah, Ludirdja and Daniel [12] are calculated, pointing out the improvements of toughness and durability of the new V~trotex-Saint-Gobain AR-GFRC system.

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The results of engine tests which were made, using radioactive piston rings for the measurement of engine wear, to explore the causes of start-up wear are described and discussed in this paper. The results obtained using a standard test procedure were used as data to compare the effect of applying variables immediately before and during the shut-down period. These variables included motoring the engine and changing the crankcase oil before shut-down; purging the crankcase and combustion chamber with dry nitrogen immediately the engine came to rest; and maintaining a high coolant temperature during the shut-down period. The reductions in start-up wear attributable to the variables applied have been expressed as percentages of the start-up wear incurred under the standard tests.