Compressive Strength, Permeability and Sorptivity of Sea Sand Concrete Containing Supplementary Cementitious Materials
Sea sand has not been widely used as a raw material due to its high chloride and sulphate contents.However, as an alternative material from marine sources, sea sand may become a potential candidate for solving the over-exploitation of the natural resources, especially river sand to develop infrastructures.Chloride ions in sea sand are the primary reason for limiting its use in reinforced concrete structures.Therefore, the question is whether sea sand without desalting can be used as fine aggregate for concrete production.Additionally, the supplementary cementitious materials (SCMs) such as fly ash (FA) and ground granulated blast furnace slag (BFS) can immobilize the chloride ions and improve the durability of concrete.The contribution of SCMs to performance of sea sand concrete should be studied more for a better and deeper understanding.On the other hand, the permeability and sorptivity properties which are measured by the porosity and connectivity of internal pores are related to the durability of concrete.The aim of this study was to investigate the compressive strength, permeability and sorptivity of concrete containing non-desalted sea sand (NSS) as fine aggregate and SCMs.Concrete containing desalted sea sand (DSS) and SCMs were also fabricated for comparison.Six mixture proportions were prepared with a constant water to cementitious material ratio of 0.50.The replacement ratios of ordinary Portland cement (OPC) by FA and BFS as SCMs were 15% and 45% by mass, respectively.All concrete specimens were cured at 20℃ under sealed curing condition until the designated test ages.The mechanical properties of concrete were evaluated in terms of compressive strength after 3, 7, and 28 days while the water absorption of concrete at the age of 28 days was tested according to ASTM C642 and C1585 to assess the permeability and sorptivity, respectively.The results indicate that the compressive strength of concrete using NSS was slightly higher than that of concrete using DSS under the same age regardless of SCMs.In addition, the NSS concrete showed a higher early compressive strength compared to DSS concrete, presumably due to the chloride ions.However, the gain in compressive strength of concrete by using NSS decreased with time.Although the replacement of OPC by SCMs did not improve the compressive strength of sea sand concrete at the age of 28 days, it reduced the permeability and sorptivity of concrete.Consequently, NSS could be better as fine aggregate for concrete production than DSS.Furthermore, sea sand concrete containing SCMs can not only improve the permeability and sorptivity of concrete but also reduce the use of OPC, leading to a significant reduction of CO2 emission.
Sea-sand chloride ions supplementary cementitious materials compressive strength durability
Q.V.Dang Y.Ogawa K.Kawai
Department of Civil and Environmental Engineering, Graduate School of Engineering, Hiroshima University,Higashi-Hiroshima, Japan
国际会议
福州
英文
559-567
2018-11-04（万方平台首次上网日期，不代表论文的发表时间）