The Preparation Of Geopolymer Concrete And Its Application In Construction Of Seawall Engineering

In the marine environment,the traditional Portland cement concrete is susceptible to be corroded by seawater,and the harmful ions(SO₄^2-、Cl-、Mg2+)in the seawater are easily reacted with its hydration products（calcium oxide,sulphoaluminate）,causing volume expansion and loosening the structure,which seriously affects the long-term durability of the concrete structure.The reaction products of inorganic polymer cementitious material produced by the Shenzhen Aerospace science and Technology Innovation Research Institute are not easily eroded by seawater and the microstructure is compact.Therefore,the concrete prepared by geopolymer cementitious materials is applied in the construction of seawall engineering,and it has potential application prospects.In order to promote the development and application of inorganic polymer cementitious materials,the preparation and engineering application of inorganic polymer concrete were studied in this paper.Firstly,the working performance and mechanical properties of geopolymer cementitious material and concrete are studied,and preparation method of geopolymer concrete based on working performance is proposed,and it is applied in the construction of Huilai seawall engineering.The main research results are as follows:The rheological properties and mechanical properties of geopolymer paste were studied.Bingham rheological model and Power-law rheological model can better describe the rheological properties of geopolymer paste.The shear yield stress and plastic viscosity coefficient of geopolymer paste are lower than that of Portland cement paste,and the fluidity of paste is greater than that of Portland cement paste.The shear yield stress and plastic viscosity coefficient of geopolymer mortar decrease with the increase of water-cement ratio,and increase with the increase of sand ratio.The fluidity of geopolymer paste has a good correlation with the water-cement ratio.The fitting curve of the paste is Y=452.5 X X-72.125,and the fitting curve of the mortar is Y=583 × X-78.The strength of geopolymer mortar decreases with the increase of water-cement ratio.When the water-cement ratio is less than 0.45,it decreases slowly,and when the water-cement ratio is greater than 0.45,it decreases significantly.The strength of geopolymer mortar increases first and then decreases with the increase of sand ratio.When the ratio of sand-cement is 3,the flexural strength of geopolymer mortar are better.The effects of unit water content,water-cement ratio and sand ratio on the performance and mechanical properties of geopolymer concrete were studied.The preparation method of geopolymer concrete based on the working performance was proposed,and the tested.In terms of the working performance,unit water content is the primary factor affecting the working performance of geopolymer concrete.When the unit water content exceeds a certain threshold of 180 kg/m3,the working performance of concrete will increase significantly.The ratio of water to binder has a certain influence on the working performance of concrete,and the geopolymer concrete with water-cement ratio of 0.45 to 0.55 has better working performance.The working performance of concrete is better when the sand ratio is about 35%.In terms of mechanical properties,water-cement ratio is the primary factor affecting the mechanical properties of geopolymer concrete.The effect of unit water content and sand ratio on the mechanical properties of concrete is not significant.The development of the compressive strength of geopolymer concrete is mainly concentrates on the first 7 d,and the 7 d strength of concrete countes for 73.4%～88.6%of 28 d strength.The 7 d compressive strength of geopolymer concrete has a good linear relationship with the water-cement ratio,and the relationship is f’ cu,0=15.648B/W + 6.526.The preparation method of the geopolymer concrete based on the working performance is established.Firstly,the strength of concrete is determined,and the compressive strength of 7 d concrete is calculated according to the 7 d and 28 d concrete compressive strength ratio（0.70～0.88）.The water-cement ratio is determined by the relationship between the compressive strength of 7 d concrete and the ratio of glue water;the unit water content is determined according to the water-cement ratio and the work performance of the construction requirements.The sand ratio is determined by the maximum particle size of the aggregate and water-cement ratio.Finally,the quality method is used to determine the sand and stone consumption.The geopolymer concrete was applied to the construction of seawall engineering in Huilai County of Guangdong province.The engineering quality is detected and monitored,and the effect of the engineering is evaluated.The working performance and mechanical properties of the prepared geopolymer concrete meet the requirements of construction.Its working performance is equal to that of ordinary concrete,and its mechanical properties are superior to that of ordinary concrete.The strain of geopolymer concrete is due to the shrinkage of concrete.The distribution of strain at every position of concrete panel is same as that of ordinary concrete.Along the length of the slope,the strain on the upper position of the concrete panel is larger than that of the lower position,and the strain in the middle position of the concrete panel is larger than the upper and lower positions along the direction of the embankment axis.The strain of geopolymer concrete conforms to the relevant provisions of the "code for design of concrete structure"（<330 με）,and its maximum strain value（276με）is 23 με higher than the maximum value of the ordinary concrete（253 με）.After construction,the geopolymer concrete structure is compact,and the appearance of aggregate and honeycomb hole is not found,and the construction effect is good.