Cement slurry additive for foundation treatment
Technical Field
The invention belongs to the field of foundation treatment of geotechnical engineering, and particularly relates to a cement slurry additive for foundation treatment.
Background
Along with the economic development and the expansion of cities, mountain-opening backfilling fields are more and more, and partial soil-filling areas even reach hundreds of meters. Such formations are characterized by: the filling depth is large, the opening mountain is obtained, the backfill particle size is large, the filling is uneven and loose, the consolidation is not completed, and the like. The construction of the jet grouting pile in the large-pore and loose stratum becomes a great problem in the geotechnical engineering field.
The traditional high-pressure jet grouting process has the defects that the grout loss in the stratum is serious due to the large fluidity of cement grout, the grouting range cannot be effectively controlled, the pile forming quality is unreliable, and even the pile cannot be formed. Therefore, the traditional high-pressure jet grouting pile process is not suitable for large-pore and loose strata such as mountain-opening backfill, riprap reclamation, sea filling and the like.
The composite paste slurry is adopted for grouting, but the fluidity of the composite paste slurry is low, the pipe blockage phenomenon can occur when a high-pressure rotary spraying process is adopted, and the grouting pump cannot pump at all. Therefore, the grouting process adopting the composite paste can not directly drill into the guniting, a sleeve is required to follow the pilot hole, then the grouting pipe is put down, and grouting is carried out after the sleeve is lifted at last, so that the construction efficiency is low.
Disclosure of Invention
In order to solve the technical problems, the invention provides a cement slurry additive for foundation treatment, which has obvious thickening effect and can effectively regulate and control the initial fluidity and initial setting time of cement slurry. After the additive is added into the cement paste, the fluidity of the cement paste is rapidly reduced, the cement paste can not run off in a high-rockfill stratum which is large in pores and loose and contains a large amount of rock blocks, the cement paste can be rapidly initially set, and the cement paste and the rock blocks are bonded to form a cement soil pile with certain strength.
In order to achieve the purpose, the invention adopts the following technical scheme:
a cement slurry additive for foundation treatment comprises the following components: the concrete comprises a quick setting component, a mineral admixture, an early strength component and an excitation component; and uniformly mixing the components in a mechanical stirring manner to obtain the cement slurry additive for foundation treatment.
Further, the cement slurry additive for foundation treatment comprises the following components in parts by weight: 0.60-0.85 part of quick setting component, 0.07-0.13 part of mineral admixture, 0.03-0.12 part of early strength component and 0.05-0.15 part of excitation component.
Further, the cement slurry additive for foundation treatment comprises the following components in parts by weight: 0.85 part of quick setting component, 0.07 part of mineral admixture, 0.03 part of early strength component and 0.05 part of excitation component.
Further, the quick-setting component is one or more of sodium metaaluminate, potassium metaaluminate, aluminum sulfate, activated aluminum hydroxide and activated aluminum oxide.
Further, the mineral admixture is ash containing active silicon-aluminum and having latent hydraulic property or pozzolanic property, and comprises one or more of granulated blast furnace slag powder, ultrafine fly ash and silica fume, wherein the fineness particle size of the ultrafine fly ash is 100-300 meshes.
Further, the early strength component is one or more of sodium nitrate, sodium nitrite, calcium formate, calcium chloride and urea.
Further, the excitation component is one or more of sodium sulfate, calcium sulfate, sodium carbonate and sodium silicate.
In the cement slurry additive for foundation treatment provided by the invention, aluminum salt has both acid and alkali properties, forms active aluminum hydroxide in the alkaline environment of cement, reacts with gypsum in the cement to generate calcium hydroxide with low solubility, and Ca in the system2+The concentration is reduced, the delayed coagulation of gypsum is weakened, the hydration of tricalcium aluminate is accelerated, heat is released, water in the system is consumed, and simultaneously, oxyhydrogenCalcium is dissolved to quickly form ettringite crystals, so that the thickening of the slurry is accelerated; the mineral admixture has hydraulicity, generates a cementitious component mainly comprising hydrated calcium silicate with low calcium-silicon ratio under the action of an excitant, and increases the consistency of cement slurry; the activator also improves the alkalinity of the system and accelerates the rapid hydration of the cement slurry system.
Compared with the prior art, the invention has the following beneficial effects:
the additive is prepared by uniformly mixing the quick-setting component serving as a main raw material with the mineral admixture, the early strength component and the excitation component, solves the problems of overlarge initial fluidity and overlong initial setting time of cement slurry under the condition of high cement ratio, and realizes effective regulation and control of the initial fluidity and the initial setting time of the cement slurry.
Detailed Description
Comparative example 1
(1) Weighing dry raw materials of the cement slurry additive for foundation treatment according to the following weight percentages: 0.5kg of sodium metaaluminate, 0.05kg of activated alumina, 0.17kg of silica fume, 0.13kg of calcium formate and 0.15kg of sodium sulfate; mixing the above materials in a blender, mixing to obtain powder additive, sealing and storing;
(2) weighing the prepared additive according to 3% of the cement mass, mixing the additive with cement slurry with a water-cement ratio of 0.95, uniformly stirring the mixture by using a high-speed stirrer, measuring the initial fluidity of the slurry, and measuring the initial setting time of the slurry in a standard curing room with the relative humidity of more than or equal to 90%.
Comparative example 2
(1) Weighing dry raw materials of the cement slurry additive for foundation treatment according to the following weight percentages: 0.8kg of sodium metaaluminate, 0.08kg of activated alumina, 0.04kg of silica fume, 0.03kg of calcium formate and 0.05kg of sodium sulfate; mixing the above materials in a blender, mixing to obtain powder additive, sealing and storing;
(2) weighing the prepared additive according to 3% of the cement mass, mixing the additive with cement slurry with a water-cement ratio of 0.95, uniformly stirring the mixture by using a high-speed stirrer, measuring the initial fluidity of the slurry, and measuring the initial setting time of the slurry in a standard curing room with the relative humidity of more than or equal to 90%.
Comparative example 3
(1) Weighing dry raw materials of the cement slurry additive for foundation treatment according to the following weight percentages: 0.8kg of sodium metaaluminate, 0.1kg of activated alumina, 0.07kg of silica fume and 0.03kg of calcium formate; mixing the above materials in a blender, mixing to obtain powder additive, sealing and storing;
(2) weighing the prepared additive according to 3% of the cement mass, mixing the additive with cement slurry with a water-cement ratio of 0.95, uniformly stirring the mixture by using a high-speed stirrer, measuring the initial fluidity of the slurry, and measuring the initial setting time of the slurry in a standard curing room with the relative humidity of more than or equal to 90%.
Example 1
(1) Weighing dry raw materials of the cement slurry additive for foundation treatment according to the following weight percentages: 0.75kg of sodium metaaluminate, 0.07kg of active aluminum hydroxide, 0.08kg of granulated blast furnace slag powder, 0.05kg of sodium nitrate and 0.05kg of calcium sulfate; mixing the above materials in a blender, mixing to obtain powder additive, sealing and storing;
(2) weighing the prepared additive according to 3% of the cement mass, mixing the additive with cement slurry with a water-cement ratio of 0.95, uniformly stirring the mixture by using a high-speed stirrer, measuring the initial fluidity of the slurry, and measuring the initial setting time of the slurry in a standard curing room with the relative humidity of more than or equal to 90%.
Example 2
(1) Weighing dry raw materials of the cement slurry additive for foundation treatment according to the following weight percentages: 0.7kg of potassium metaaluminate, 0.05kg of aluminum sulfate, 0.04kg of ultrafine fly ash (100 meshes and 300 meshes), 0.03kg of silica fume, 0.03kg of calcium formate, 0.05kg of sodium sulfate and 0.1kg of sodium carbonate; mixing the above materials in a blender, mixing to obtain powder additive, sealing and storing;
(2) weighing the prepared additive according to 3% of the cement mass, mixing the additive with cement slurry with a water-cement ratio of 0.95, uniformly stirring the mixture by using a high-speed stirrer, measuring the initial fluidity of the slurry, and measuring the initial setting time of the slurry in a standard curing room with the relative humidity of more than or equal to 90%.
Example 3
(1) Weighing dry raw materials of the cement slurry additive for foundation treatment according to the following weight percentages: 0.6kg of sodium metaaluminate, 0.07kg of granulated blast furnace slag powder, 0.06kg of silica fume, 0.04kg of sodium nitrite, 0.08kg of calcium chloride, 0.03kg of sodium silicate and 0.12kg of sodium carbonate; mixing the above materials in a blender, mixing to obtain powder additive, sealing and storing;
(2) weighing the prepared additive according to 3% of the cement mass, mixing the additive with cement slurry with a water-cement ratio of 0.95, uniformly stirring the mixture by using a high-speed stirrer, measuring the initial fluidity of the slurry, and measuring the initial setting time of the slurry in a standard curing room with the relative humidity of more than or equal to 90%.
Example 4
(1) Weighing dry raw materials of the cement slurry additive for foundation treatment according to the following weight percentages: 0.6kg of sodium metaaluminate, 0.13kg of aluminum sulfate, 0.05kg of granulated blast furnace slag powder, 0.02kg of ultrafine fly ash (100 meshes and 300 meshes), 0.04kg of sodium nitrate, 0.03kg of urea, 0.02kg of calcium sulfate and 0.08kg of sodium carbonate; mixing the above materials in a blender, mixing to obtain powder additive, sealing and storing;
(2) weighing the prepared additive according to 3% of the cement mass, mixing the additive with cement slurry with a water-cement ratio of 0.95, uniformly stirring the mixture by using a high-speed stirrer, measuring the initial fluidity of the slurry, and measuring the initial setting time of the slurry in a standard curing room with the relative humidity of more than or equal to 90%.
Example 5
(1) Weighing dry raw materials of the cement slurry additive for foundation treatment according to the following weight percentages: 0.8kg of sodium metaaluminate, 0.05kg of activated alumina, 0.07kg of silica fume, 0.03kg of calcium formate and 0.05kg of sodium sulfate; mixing the above materials in a blender, mixing to obtain powder additive, sealing and storing;
(2) weighing the prepared additive according to 3% of the cement mass, mixing the additive with cement slurry with a water-cement ratio of 0.95, uniformly stirring the mixture by using a high-speed stirrer, measuring the initial fluidity of the slurry, and measuring the initial setting time of the slurry in a standard curing room with the relative humidity of more than or equal to 90%.
Example 6
(1) Weighing dry raw materials of the cement slurry additive for foundation treatment according to the following weight percentages: 0.62kg of potassium metaaluminate, 0.15kg of aluminum sulfate, 0.05kg of activated alumina, 0.03kg of granulated blast furnace slag powder, 0.05kg of ultrafine fly ash (100 meshes and 300 meshes), 0.03kg of sodium nitrate, 0.02kg of calcium chloride, 0.02kg of calcium sulfate and 0.03kg of sodium carbonate; mixing the above materials in a blender, mixing to obtain powder additive, sealing and storing;
(2) weighing the prepared additive according to 3% of the cement mass, mixing the additive with cement slurry with a water-cement ratio of 0.95, uniformly stirring the mixture by using a high-speed stirrer, measuring the initial fluidity of the slurry, and measuring the initial setting time of the slurry in a standard curing room with the relative humidity of more than or equal to 90%.
Example 7
(1) Weighing dry raw materials of the cement slurry additive for foundation treatment according to the following weight percentages: 0.68kg of sodium metaaluminate, 0.1kg of aluminum sulfate, 0.03kg of granulated blast furnace slag powder, 0.04kg of ultrafine fly ash (100 meshes and 300 meshes), 0.03kg of sodium nitrite, 0.04kg of calcium formate, 0.05kg of sodium sulfate and 0.03kg of sodium silicate; mixing the above materials in a blender, mixing to obtain powder additive, sealing and storing;
(2) weighing the prepared additive according to 3% of the cement mass, mixing the additive with cement slurry with a water-cement ratio of 0.95, uniformly stirring the mixture by using a high-speed stirrer, measuring the initial fluidity of the slurry, and measuring the initial setting time of the slurry in a standard curing room with the relative humidity of more than or equal to 90%.
The detailed components of the additives prepared in comparative examples 1-3 and example 5 are shown in table 1.
TABLE 1 additive Components of comparative examples 1-3 and example 5
The slurries prepared in comparative examples 1 to 3, examples 1 to 7 and the blank comparison (cement paste having a water cement ratio of 0.95 as the blank comparison) were tested in the same manner, and the test results are shown in tables 2 and 3.
TABLE 2 test data for comparative examples 1-3 and example 5
|
Fluidity/mm of mixed slurry
|
Initial setting time/min
|
Example 5
|
65
|
60
|
Comparative example 1
|
126
|
110
|
Comparative example 2
|
62
|
32
|
Comparative example 3
|
135
|
120
|
Blank comparison
|
250
|
600 |
As shown in Table 2, the fluidity and the initial setting time of the mixed slurry in example 5 are better than those of comparative examples 1 to 3, the amount of the quick setting component is increased in comparative example 2, the fluidity is not much different from that of example 5, but the initial setting time is reduced, which is not good for the subsequent work of implanting the pipe pile into the cement pile.
TABLE 3 application Performance test results of additives
As can be seen from Table 3, the cement slurry additive of the present invention greatly improves the initial flow rate and initial setting time of the slurry.
The present invention is not limited to the above-mentioned embodiments, and the formulation of the additive may be adjusted according to the actual formation and the like on the basis of the test.
The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.