چكيده به لاتين
Abstract:
Due to the fact that by producing cement, a main constituent of concrete, huge amounts of CO2 enter the atmosphere, it is necessary to increase the service life of concrete structures, and consequently reduce the rate of cement production, to reach sustainable development. Concrete is a heterogeneous mixture of cement, water and fine and coarse aggregates, which are completely inconsistent, therefore pore formation is inevitable. By entering CO2 and aggressive dissolved ions into concrete through these pores, the degradation process starts. Thus, hindering the harmful factors from diffusion to the concrete should be done to increase service life of concrete. Surface sealing is a method which is utilized to decline the concrete diffusivity. In this survey, two kinds of inorganic sealers namely sodium silicate solution (waterglass) and colloidal Nano silica and to make comparison with organic sealers tetraethyl orthosilicate (TEOS) were applied on the surface of concrete specimens to evaluate the efficiency of each substance on compressive strength, permeable void percentage and water absorption. All tested compounds reduce the concrete diffusivity, and hence permeable void percentage and water absorption. Among different sealers, applying TEOS for four times on the concrete surface exhibited the best performance due to 10% and 9% reduction in the water absorption and permeable void percentage, respectively. Colloidal Nano Silica with concentration of 30% by 9% reduction in water absorption and 7% decrease in the percentage of permeable void was ranked in the second place among different sealers. In case of applying water-glass, water absorption and permeable void percentage have been declied by 5% and 6%, respectively. It should be noted that the compressive strength has not changed noticeably.
Keywords: Permeable Void, Water Absorption, Compressive Strength, Sodium Silicate, Nano-Silica, Tetraethyl orthoSilicate
