Effect of Cement Paste Content on Shrinkage of Concrete
Shrinkage in concrete is a material property that builders and researchers greatly desire to control. An excess amount of water that does not react in the hydration process of cement stays inside the concrete creating water pores. Water inside the pores is removed when it is evaporated from the surface. The movement of water from the surface generates a pore pressure inside the concrete, causing a volume contraction called shrinkage. The objective of this investigation is to study shrinkage as the cement paste content is changed by volume. For this investigation, a designed optimized concrete mixture (DOC) was studied. A DOC differs from a normal concrete mixture in the aggregate quantity, gradation and the amount of cementitious material. To study shrinkage, a set of restrained shrinkage, free shrinkage, compression and split tensile tests were conducted on concrete following the ASTM standards. Ring tests were used for the study of restrained shrinkage and prisms were used for the free shrinkage tests. The results show that concrete mixtures with a higher cement paste content have a higher strain over time for the free shrinkage and restrained shrinkage tests. Compressive strength results show that a higher cement paste content does not necessarily result in higher strength. Furthermore, experimental and computer model results for strain shown an acceptable correlation using ICON finite element method code.
School:
University of Puerto Rico at Mayagüez
Department:
Civil Engineering
Research Advisor:
David A. Lange
Department of Research Advisor:
Civil Engineering
Year of Publication:
2007