| This article relies on the National Natural Science Foundation of China (51278497). In order to achieve the energy-saving,salvaging and improve the performance of early cracking of cemen-based materials by scientifically and rationally using of ground limestone in concrete,this paper focuses on the ground limestone based cementitious material flow performance testing and the early cracking resistance test.The main contents and conclusions are as follows.1.The study of flow properties of cementitious material mixed with ground limestone.Ground limestone can improve the fluidity of the cement mortar.As the dosage of ground limestone grow,the mortar fluidity grows too.The fly ash plays the same role.The ground limestone and the fly ash will make a additive effect if both were mixed into cement mortar.The slag can improve the fluidity of the cement mortar.If the slag and ground limestone were both mixed into the cement mortar,the improve of the fluidity will be even more obvious.If the three of them were used together,they will work well.When the ground limestone content is fixed,the content of complexed fly ash and mineral powder fixed,the fluidity will be close.While if mixed with polypropylene fiber and steel fiber,it will reduce the fluidity of the ground limestone cement mortar.2. Cement-ground limestone Binders early cracking resistanceDoped ground limestone will affect the cement mortar cracking time, increase with the increase in the dosage of ground limestone, the specimen cracking time reduced; when ground limestone content is10%, resulting in cracking time when ground limestone content the case of30%, you can delay the cracking time, single mixed with ground limestone, cracking mortar Id basic3d crack about95%of the development of post-crack than weak; ground limestone content will affect the age of mortar crack, age cracking law consistent performance. When ground limestone content of less than10%, with the increase in the dosage of ground limestone, crack length changes from short to long, corresponding to the crack width widened by the narrow gradually increased, and the number of cracks, the mortar cracking index gradually increases; With the increase in the dosage of ground limestone, ground limestone content is greater than10%, the crack length shorter length, corresponding to the crack width is narrowed by the width gradually reduced, and the number of cracks, the mortar cracking index gradually decreases; when ground limestone content of20%, similar to the baseline group and not mixed with ground limestone; when the content of30%can significantly reduce the cracking of the hardened paste.3.Complex doped mineral admixtures on the early cracking of cementitious materialSlag can be delayed cement mortar cracking time delay ground limestone-cement mortar cracking time delay effect is more obvious with increasing slag dosage; fly ash can be delayed cement mortar cracking time, also can be delayed ground limestone-cement mortar cracking, delayed effect is more obvious with the increase in fly ash content, the slag delay effect is slightly better than the fly ash; when fly ash, slag Admixed ground limestone-the same amount of fly ash or slag cement mortar cracking delay is better than single-doped.Single granulated slag ground will delay the cracking of cement mortar6h slow development than single mixed with ground limestone; complex ground granulated slag, ground limestone, slag delay ground limestone-the cracking of cement mortar6h; single fly ash, cracking1D within basically reached3d early cracking around95%post-crack development will be weaker; the complex fly ash, ground limestone, crack1d within basically reached3d about90%of early cracking, cracks in the late weaker; the complex doped ground limestone, fly ash, slag,1d within cracking basic3d early cracking around95%, the late development of cracks weaker.Slag replacement ratio will affect the age of mortar cracking, the law of each age cracking performance. Single granulated slag ground, slag dosage increases, the crack length by length becomes shorter, the corresponding crack width by the width narrows, and gradually reduce the number of cracks, the mortar cracking index gradually decreases; complex ground granulated slag, ground limestone and single ground granulated slag mortar cracking; the influence of fly ash on the mortar age cracking than the slag is similar to the law of each age cracking performance. Single fly ash, with the increase in fly ash content, the crack length became shorter, corresponding to the crack width by the width narrowing gradually reduced, and the number of cracks in the mortar cracking index gradually decreases; complex flour-ash, ground limestone and single fly ash affect the mortar cracking.Complex mixed with ground limestone, fly ash and slag, ground limestone content of10%fly ash, slag20%each specimen crack the best results.4. The impact of fiber on early cracking of cementitious materials Polypropylene fiber can be delayed ground limestone-cement mortar cracking time, the delayed effect of the more obvious with the increase of polypropylene fiber content; steel fiber also can be delayed ground limestone-cement mortar cracking time, with steel fiber content increases, the delay effect is more obvious; when fly ash, slag, polypropylene fiber, steel fiber composite doped, can significantly delay ground limestone cement mortar cracking.Complex polypropylene fiber, ground limestone basic1d inside the cracking reached about95%of the3d early cracking, the late development of cracks will be weaker; complex steel fiber, ground limestone,1d cracking basic about95%of the3d early cracking, post-crack development will be weaker.Ground limestone, fly ash, slag, polypropylene fiber, steel fiber composite doped Id within cracking basically reached3d early cracking about90%, the development of post-crack than weak.Polypropylene fiber content will affect the age of mortar cracking, the law of each age cracking performance. Complex doped polypropylene fiber, ground limestone, polypropylene fiber content increases, the crack length became shorter, the crack width corresponding to the width narrowing,2mm>d≥1mm wide cracks was significantly reduced, and the number of cracks gradually reduced, the mortar cracking index gradually decreases; steel fiber content will affect the age of mortar cracking, the law of each age cracking performance. A complex steel fiber, ground limestone, with the increase of steel fiber content, the crack length became shorter, corresponding to the crack width by the width narrows,2mm>d≥1mm wide cracks was significantly reduced, and gradually reduce the number of cracks mortar cracking index decreases.Complex mixed with ground limestone, fly ash, slag, polypropylene fibers and steel fibers, ground limestone content of10%,20%each of the fly ash, slag, polypropylene fiber volume content of0.1%, steel fiber volume content of0.8%, the specimen strength, mobility, crack effect combined effect.5.Cement-ground limestone cementitious materials early cracking performance of three-dimensional surface fittingcement-ground limestone, cement-ground limestone-fly ash-slag-fiber composite cementitious materials, the mortar cracking the age of mortar cracking index logarithmic function; ground limestone content and mortar cracking index exists quadratic function of the relationship; mortar cracking instar X ground limestone content Y, approximate the functional relationship between the mortar cracking Index Z: Z＝A*ln(X+1)+X*(B*Y2+C*Y+W)... |
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