易流型大掺量石灰石粉复合掺合料性能研究

Experimental Study on High Content Limestone Powder Composite Admixture with Easy Flow Type

针对甘肃平凉地区大量石灰石粉得不到有效利用的问题,本文将当地的石灰石粉和粉煤灰、矿粉、降粘剂等进行复合,制备出满足JG/T 486—2015《混凝土用复合掺合料》中石灰石粉掺量不低于80%的易流型复合掺合料,研究单掺及大掺量石灰石粉复合掺合料对水泥胶砂性能的影响。结果表明:提升石灰石粉的比表面积,可以改善胶砂的流动性,提高其抗压强度,但强度的提高有限;单掺石灰石粉制备的胶砂性能较差,无法满足JG/T 486—2015《混凝土用复合掺合料》的要求和工程需要,建议和其他矿物掺合料复掺使用;三元复合掺合料的性能优于二元复合掺合料,当石灰石粉掺量为掺合料总量的80%,矿粉和降粘剂掺量均为10%时,复合掺合料的性能最佳,SF2石灰石粉复合掺合料的流动度比达到111%、7 d活性指数为71.38%、28 d活性指数为74.71%。

In response to the problem of ineffective utilization of a large amount of limestone powder in the Pingliang area of Gansu Province,this article combines local limestone powder with f ly ash,mineral powder,or viscosity reducing agents to prepare a f lowable composite admixture that meets the industry standard JG/T 486—2015 Compound Mineral Admixtures for Concrete with a stone powder content of no less than 80%,the study investigates the impact of high content limestone powder composite admixture on the performance of cement mortar.The results show that increasing the specific surface area of limestone powder can improve the f lowability of mortar and increase its compressive strength,but the strength improvement is limited.The performance of the adhesive sand prepared by single addition of stone powder is poor and cannot meet the requirements of JG/T 486—2015 Compound Mineral Admixtures for Concrete and engineering needs.It is recommended to use limestone powder in combination with other mineral admixtures.The performance of ternary composite admixtures is better than that of binary composite admixtures.When the content of stone powder is 80%of the total amount of admixtures,and the content of mineral powder and viscosity reducer is both 10%,The composite admixture has the best performance,with a f lowability ratio of 111%,a 7 days activity index of 71.38%,and a 28 days activity index of 74.71%for SF2 limestone powder composite admixture.