Cracking resistant cement-based material

Title: Cracking resistant cement-based material
Author(s): A. Turatsinze, S. Bonnet, J.-L. Granju
Paper category : conference
Book title: Fifth International RILEM Conference on Reflective Cracking in Pavements
Editor(s): C. Petit, I.L. Al-Qadi and A. Millien
Print-ISBN: 2-912143-47-0
e-ISBN: 2912143764
Publisher: RILEM Publications SARL
Publication year: 2004
Pages: 317 - 324
Total Pages: 8
Nb references: 11
Language: English

Abstract: Cement-based materials suffer from their low tensile strength and their poor straining capacity: they are sensitive to cracking, first of all to shrinkage cracking. Enhancing the cracking resistance of cementitious materials is the objective of a wide research programme in progress. In this regard, the work aims to the design of a cement-based composite exhibiting a high straining capacity before cracking localisation. It has been assumed that incorporation of aggregates with low elastic modulus is a solution. Rubber aggregates obtained from shredded non reusable tyres have been used conferring to the study an environmental interest.The control cementitious material is a mortar. Natural sand and rubber aggregates with a maximum grain size of 4 mm have been used. The behaviour of the control mortar has been compared with the one of mortars incorporating rubber aggregates partly replacing the natural sand. Two replacing volume fractions have been studied: 20 and 30 %. The synergy of rubber aggregate substitution and of fibre reinforcement has been also investigated. In this regard two dosages, 20 and 40 kg.m-3 of straight steel wire fibres, 13 mm in length and 0.16 mm in diameter have been used. As expected, results show that rubberised mortars exhibit low deformation modulus and undergo higher strain before the macrocrack formation. It appears that benefit expected from fibre reinforcement in term of ductility is not affected by rubber incorporation. However, there is one drawback: decreasing the deformation modulus of a cement-based material is accompanied by a decrease of its strength. Results also confirm that rubber aggregates incorporation increases the shrinkage length change. On the opposite trend, ring-test results demonstrate that the straining capacity enhanced by rubber aggregate incorporation widely offsets the additional shrinkage length changes: shrinkage cracking is delayed and when it occurs, the crack network exhibits thinner crack openings which make it less detrimental. For all these reasons, when strength is not a high priority, rubber aggregate incorporation is suitable to design cement-based materials with enhanced cracking resistance. The use of such materials in road construction or rehabilitation is a promising solution to prevent or significantly reduce cracking, and as a consequence, to improve the durability of cement-based structures.

Online publication: 2004-04-15
Publication type : full_text
Public price (Euros): 0.00