Insulation construction In the winter, various insulation measures are taken for the masonry masonry so that the masonry mortar is maintained at a certain temperature to obtain the necessary strength. The winter construction of the masonry project is performed by adopting the thermal insulation method. Common methods include a thermal storage method, a warm water mixing method, a warm greenhouse method, and a heating method.
Heat storage method The construction of heat storage method is suitable for areas with little or no positive and negative temperature changes in winter, freezing at night, and thaw during the day. The winter in these areas is characterized by low temperatures in the morning and evening, freezing, and high temperatures at noon.
According to this rule, proper construction arrangements can be made to use the high temperature at noon to speed up the construction of bricks. At the same time, the east wall is erected in the morning, the west wall is built in the afternoon, and the interior wall is built sooner or later. After completion, it is covered with straw mats and other insulation materials. By adopting the above measures, the internal heat of the masonry wall and the hydration heat generated when the cement mortar is hardened can not be easily lost, and the temperature can be maintained, so that the mortar can obtain the required strength before being frozen.
If the weather suddenly becomes cold, but the weather is suddenly cold, but at night, not less than.,, day and night average higher than, in order to allow the finished masonry can continue to be completed, the use of warm water and hot mix construction, so that the temperature of the mortar is not low In the preparation of mortar can not be too much at one time, with the progress of masonry closely, with the mix with the use. The masonry that was built during the day was covered with insulation materials such as straw mats, sandstone, and membranes at night.
Warm Shed Construction Warm Shed Construction, that is, the winter masonry brick masonry in the warm shed.
The shed is generally equipped with a hot-air generator or a furnace to allow the mortar to condense at a higher temperature. When using this method, the temperature of sand, stone, brick and other materials shall be above, and the temperature of mortar mixed after warming sand and water shall not be lower than, and at the same time, watered and cured. The curing time, depending on the required strength and heating temperature, is generally not less than.
day and night.
This method requires a certain amount of heating equipment and fuel for construction materials, which are generally used in the case of individual local restoration projects or when construction time requirements are urgent.
Heating method This is the method of heating by electric heating or steam, heating the wall of the masonry internally or externally, so that the mortar rapidly condenses at high temperatures. Electrothermal heating, the electrode should be uniformly placed in the joints in the masonry.
When the steam is heated, it is covered with a temporary shutter or canvas or the like around the masonry, and steam is introduced into the lower part. The heating is performed before freezing, and the heating time is determined according to the required masonry strength.
This method has a good construction effect, but the construction requirements are complex and the cost is high. It is only used for high individual strength and stability requirements, as well as the part of the repair project that needs to be used immediately.
In addition, when the brick masonry structure is prepared by the heat preservation method, in order to accelerate the mortar condensation and shorten the holding time, an early strength agent such as calcium chloride may be generally used. Its dosage should be determined experimentally. The addition of calcium chloride can greatly increase the strength of cement mortar of the same age. The comparison of calcium chloride content and mortar strength is shown in the table: Calcium chloride content mortar strength comparison table Mortar age (day plus calcium chloride and cement weight ratio Note: The strength of mortar without an early strength agent is Sichuan water conservancy Xie Zuguo: winter construction technology of farmland water conservancy project frost-resisting mortar construction In masonry mortar, a certain amount of anti-freezing agent is mixed. After masonry, the mortar is slowly frozen and has a certain strength in the freezing process. For the design strength of !), after thawing, the adhesive strength of the mortar can continue to increase as in the normal temperature, and the strength of the mortar is almost the same as when it is not frozen. This kind of anti-freezing agent is mixed in the mortar to make Mortar early (that is, the method of avoiding freezing before a certain strength is called frost-resisting mortar method. Cement mortar mixed with anti-freezing agent or cement-lime mortar is called frost-free mortar (also called cold-resistant mortar).
Anti-freeze mortar, commonly used antifreeze agents are mainly sodium chloride (salt, calcium chloride, sodium nitrite, potassium carbonate, etc.. The amount of antifreeze is generally determined through tests. Commonly used antifreeze Sodium Chloride and Calcium Chloride Dosages and Applicable Temperatures See table Antifreeze Mortar Antifreeze Dosage Reference Table Estimated daily average temperature over ten days (, Sodium chloride (Saline calcium chloride Note: Dosage in accordance with mixing water As a percentage, two chlorine salts are used simultaneously.
In general, sodium chloride is often used as an antifreeze.
Because at the negative temperature, the anti-freezing mortar mixed with salt grows faster than the mixed calcium chloride, and the salt supply is easy to solve. If only sodium chloride is used as an antifreeze, the amount may refer to the table. When the antifreeze is incorporated with salt, the salt solution should be adjusted first by dissolving the dried salt in about warm water and measuring it with a pycnometer. The specific gravity is calculated to determine the amount of salt solution in the mortar.
Separate use of sodium chloride antifreeze content of reference value table masonry type mixture temperature applies to brick masonry above, the minimum temperature, the lowest temperature below the stone masonry. ) Above, minimum temperature below, minimum temperature below Note: Dosage is calculated as a percentage of the weight of the mixing water.
Cement used in frost-resisting mortars must be Portland cement or ordinary cement in cold areas, and pozzolan cement, slag cement or fly ash cement in other areas. In addition to the general requirements, the sand used should be as large as possible.
At the same time, the temperature of antifreeze sand must not be lower than that when used. ,, For this purpose, hot mortar can be mixed. According to different temperatures, the temperature of the heating mortar can be used to refer to the table. The required temperature of the mortar is not higher than the outdoor temperature when the masonry is built. (The minimum temperature of the mortar when paving) (When the weather is low and the weather is low, the average day-night temperature is low. At that time, the mortar markings for masonry bearing masonry should be increased by one level compared with that at normal temperature.
The frost-resisting mortar masonry shall be covered after masonry work to prevent ice and snow from infringement, and shall not be watered and maintained.
When the amount of chlorine salt antifreeze is too large, it will increase the phenomenon of salt precipitation in the masonry, make the surface of the masonry white, increase the moisture absorption of the masonry, reduce the insulation of the masonry, and at the same time have a Corrosion effect. Therefore, this law is not used for wall posts that have special requirements such as insulation, insulation, and surface decoration. When using a chloride salt as a cryoprotectant for reinforced masonry, in addition to strictly controlling the amount of addition, rust inhibitors (such as sodium nitrite) must be incorporated.
Masonry Masonry Winter Construction Considerations In addition to the above-mentioned different construction methods, masonry masonry construction in winter may be based on the actual situation. Attention shall also be paid to the following issues: If masonry materials are frosty, they should be built before masonry. Clear, but do not rinse with water. Sand must not contain ice and frozen blocks.
Lime paste should be protected from freezing. If it freezes, it should be melted and remixed before use. Lime paste dehydrated and weathered should not be used.
Mortar should use cement mortar or cement lime mortar, lime mortar, clay mortar or lime clay mortar shall not be used.
The reason is that the strength of the latter is low, it is destroyed when it is frozen, and its strength cannot continue to increase after thawing. At the same time, the fluidity of the mortar should be increased more than that at room temperature.
When mixing mortar, water and sand can be properly warmed, but the water temperature must not exceed, and the sand temperature must not exceed 1, and cement and sand should be added first.
It is forbidden to use mortar that has been frozen and mixed with hot water.
In the winter construction project of the construction plan, the construction plan of the winter Sichuan water conservancy season shall be prepared in advance, the engineering materials shall be prepared, the winter construction methods shall be selected and determined, and all construction preparations shall be made.
Masonry is constructed in strict accordance with a shovel ash, a brick, and a squeeze and knead operation method. The seam should be controlled, the masonry mortar should be compacted, and the mortar should be used with the mixture. Do not accumulate too much ash in the ash tank or ash bucket to prevent freezing. It is forbidden to use the grouting method to masonry.
Every day, the height difference between the masonry height and the temporary break shall not be greater than! . Breaks should be made at the break. When using a straight rake, it is advisable to have three brick-level horizontal joints, one for each extension, and not less than each side, so as to ensure that the internal and external walls are connected.
The foundation must be set on unfrozen foundations. During the construction period and after completion of the construction, the foundation must not be frozen. Digging the design elevation in the foundation pit, the foundation temperature is slightly higher. / Immediately pour or masonry.
At the same time, when laying the foundation, one side of the construction should be backfilled with unfrozen soil on both sides. After the brick is built, unfrozen soil or slag is used to fill the foundation pit and cover the upper surface with straws, straw bags and other insulation materials.
The top surface of masonry should not be covered with ash on the day off work. Apply insulation on the masonry to prevent freezing.
Under winter construction conditions, masonry masonry that has not taken antifreeze measures shall not be frozen until the strength of the mortar reaches the design number.
In winter construction, special attention should be paid to strengthening safety measures such as fire prevention and coal gas poisoning.
In order to ensure the construction quality of masonry in winter, various quality inspections and construction records shall be strengthened during construction. Outdoor air temperature, greenhouse temperature, and mortar temperature were measured at least once a day; the amount of antifreeze was checked at least once a day. Do a good mortar test and carry out standard maintenance. Masonry winter construction, the mortar markings should be based on the test results of the test specimens under the maintenance of the standard conditions, and at the same time every day should also be made with the same condition of the masonry curing of the test specimens, in order to understand the actual conditions of mortar strength growth.
Winter Plaster Construction Winter Plastering Practices Where the average temperature is lower than day and night. When the minimum temperature is lower than /, the plastering works should be carried out in accordance with the provisions of the winter construction. At the same time, the minimum temperature of the indoor and outdoor construction sites during construction shall not be less than the requirements for advanced plastering and facing works. / For intermediate and ordinary plastering works, the requirements for winter plastering are not lower than those for winter plastering. There are mainly hot and cold working methods. The hot work is to appropriately increase the temperature at the construction site and maintain the site temperature. Plastering is carried out under the condition of / and the cold working method is to incorporate a chemical antifreeze 3 in the mortar, such as the aforementioned salt solution 4, and mix it into a frost-resisting mortar without any heating and heat-insulating construction method.
Construction preparation preparation organization preparation. Formulate construction organization plans, select and determine construction methods, perform winter construction techniques, and provide winter construction technical training when necessary. We will compile the classes, implement the responsibilities to the teams, implement them, and implement the post responsibility system. Salt, temperature measurement, heat preservation, fire and other major tasks must all be handled by special personnel, and there are special people to do a good job of construction records.
Preparation of heat sources and equipment. If you use a hot method, you must prepare a heat source in advance. In the case of indoor plastering, heating by means of radiators or hot air can be used conditionally; when conditions are not available, furnaces with chimneys can be installed in suitable locations. For projects with large amount of ash, if conditions permit, use vertical boiler to burn steam or hot water, use hot water to mix mortar, use steam to heat sand, and increase the temperature of mortar operation; conditions are not available or the amount of plaster is less At the same time, there must be a fire in the mixer shed or other heating sources.
If cold work is used, containers 3 prepared with anti-freezing agents such as casks, iron buckets, etc., a density meter for measuring the solution, a consistency meter for measuring the consistency of the mortar, and a thermometer for measuring the temperature at the construction site must be prepared in advance.
Insulation measures. Construction sites and materials for plastering in winter should have insulation measures. For example, when plastering, it is necessary to install the door and window glass first, and the holes that are easy to ventilate and ventilate are to be tightly closed; windshields or straw curtains should be hung outside the walkway or door; and plastering materials such as yellow sand and lime plaster should be used. Insulation material is tightly covered.
Construction measures are to be constructed in a hot manner and the indoor temperature should be within. /the above.
The mortar is mixed with hot water and hot sand, and the insulation, mixing and transportation of the mortar are reinforced. The temperature of the mortar during operation is not lower than that of the cold construction. The main purpose is to mix and determine the antifreeze. The amount of antifreeze salt should be increased or decreased according to the temperature.
In addition, it is also possible to add sodium sulphate and salt, or a mixture of sodium sulphate, sodium nitrite and salt in the plaster. Antifreeze mortar mixed with such antifreeze can be applied under the air temperature.
When cold construction is used, the surface of the grass-roots level is not watered and wet, and ice slag and frost on the surface must be washed with hot salt water, and no watering and maintenance are required after the construction.
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