With the increasing emphasis on building energy conservation and environmental protection, roof insulation and waterproof technology have developed rapidly. China's existing roof insulation materials are: expanded perlite, polystyrene foam, expanded vermiculite, etc.; waterproof material is mainly waterproof coating, modified asphalt waterproof membrane, polymer waterproof membrane and cement polystyrene board upside down The determination of the consolidation rate, strength and other indicators based on the determination of the gel time should be extended and controlled at 5 ~ 12h, groundwater development, the slurry gel time should be adjusted short.
Q) In the strongly weathered and fully weathered rock formations and clay layers with poor self-stabilizing ability, the shield grouting single slurry and double slurry are optional, the gel time is appropriately shortened to 4~7h, and the synchronous grouting pressure is 0.15~0.2MPa, if necessary, secondary replenishment and construction reinforcement measures.
Grouting in a water-rich formation requires rapid water resistance and rapid filling. Therefore, it is required that the slurry has a short solidification time, high viscosity, strong water retention, and no segregation, and the gelation time should be controlled at 4 to 6 hours. In the initial and arrival stages of the shield, the slurry gel time is generally required to be shortened in order to fill the formation. At the same time as early as possible to obtain the strength of the slurry consolidation, to ensure that the roof and so on. During the construction of these materials, the insulation and waterproofing will be carried out in two phases. The disadvantages are two: First, the complementarity between the waterproof material and the insulation material is poor, the construction is troublesome and the cost is high; second, the polymer material has poor anti-aging properties. Shorter life expectancy. In this study, ordinary Portland cement and quicklime were used as cementitious materials, and heat-insulating materials (expanded perlite), fly ash, water repellent, water repellent, foaming agent, and a small amount of additives were added to develop heat insulation and insulation. Waterproof function as a whole, make full use of industrial waste, new construction materials with low cost. The material has the characteristics of light weight, heat insulation and waterproof, and the construction is completed at room temperature once. The prepared roof insulation waterproof board is safe from open excavation and prevents leakage of pulp from the opening.
From the construction process of the entire passenger-large shield construction, the grouting quality is well understood and the ground settlement is controlled within +10~-30mm, which does not cause building settlement, tilt, and cracking. The insufficiency of this project is that it is too conservative in the adjustment of construction parameters. For example, the main geology in the test section is the residual soil and the rock fully weathered stratum. The injection rate A should be adjusted from 1.6 to 1.4, but it does not dare to adjust, resulting in waste. In the moderately weathered formation, because the part of the shield tail-stopping pulping plate has fallen off, the grouting pressure cannot reach 1.5 MPa, but the construction instruction still requires 1.5 MPa, causing a large amount of slurry to enter the earthen storage and cause economic loss. Therefore, the shield grouting construction must be reasonable and scientific.
Zhang Jie, et al.: Research on waterproofing and anti-cracking of roof insulation board 1 Principle of heat preservation and waterproofing and ratio of materials 1.1 Insulation waterproof board Raw Material 32.5 Ordinary portland cement, expanded perlite, fatty acid salt waterproof agent (homemade), foaming agent ( Self-made), hollow glass microspheres, water repellent (homemade), quicklime, fly ash, admixture.
1.2 Insulation Waterproofing Raw material ratio and production ratio are: m (cement) m (lime) m (expanded perlite) m (fly ash) m (hollow glass beads) m (foaming agent) m (fatty acid salt Waterproofing agent) m (external expanding pearlite has high water absorption rate. To reduce the water-cement ratio and improve the waterproof performance, it is necessary to first treat the expanded perlite with hydrophobic water: press m (water) m (soap) m (alum): m ( Sodium methylsiliconate) = 1002.50.10.5, and the water repellent agent is obtained after uniformly stirring in the container, the water repellent agent is charged into the atomizer, the perlite is loaded into the mixer, and the perlite particles are expanded under stirring. Spray the water repellent on the surface until no dry material is present, then let it dry naturally.
First premix hollow glass microspheres with cement, mix Portland cement, quicklime, fly ash, water-impregnated expanded perlite, hollow glass microbeads and admixtures in a blender according to the ratio, and add The dilute fatty acid salt waterproofing agent and foaming agent are mixed and poured into the mold.
Insulation principle Insulation waterproof mortar insulation and insulation effect is the expansion of perlite and hollow glass beads. Expanded perlite: bulk density of about 100kg/m3, thermal conductivity 0.03-.04W (nrK); hollow glass microspheres: products produced by the United States Potter Industries Lnc, the appearance of white fine powder, particle morphology is The rigid hollow spheres have an average particle size of 45 wm and a thermal conductivity of 0.057 W/(m*K) and a bulk density of about 180 kg/m3. A small amount of foaming agent is added into the mortar to generate a large number of closed bubbles that are small, evenly distributed, and do not collude with each other through stirring, so that the capillary becomes fine, tortuous, and disperse, the water seepage channel is reduced, and the mortar thermal insulation performance is improved.
Waterproof principle The waterproof principle of waterproof agent is divided into two kinds of situations. One is the non-reactive type: the water repellent is filled or covered on the surface of the material in the cementitious material, and the organic matter and the inorganic matter are only filled with each other in an inert manner and mechanically, and the expanded perlite treated by the hydrophobic water belongs to this kind of situation; This is a reactive type: the active group of the water repellent chemically reacts with the hydration product in the cementitious material to form a chemically bonded interface structure. The water-repellent agent containing a COO-containing compound reacts with Ca 2+, a hydration product of cement, to form a hydrophobic precipitate, and is oriented on the capillary wall to form a "anti-capillary effect" to improve the waterproof property of the material. . The added fatty acid salt water repellent is a reactive type. Since the fatty acid salt water repellent is a soluble surfactant, when it is added in a small amount, the waterproof effect cannot be achieved. When the added amount is too large, the waterproof properties and compressive strength of the 74 new construction materials of the material are reduced.
The water absorption rate of the heat-insulating water-proof board obtained by adding only the water-repellent agent, the water-repellent agent in the mortar, and the expanded perlite treated by the water-repellent treatment is seen in the mortar.
Fig.1 Relationship between soaking time of different insulation and waterproof boards and water absorption of the insulation board 1.5 Preparation of fatty acid salt water repellent Add 31 kg of water to the reactor and heat the temperature to 70 1.5 kg. Add 2.5 kg of oleic acid while stirring. Stir and place for 3 h. The temperature dropped to 50C, added 3kg of triethanolamine, stirred, and left for 2h. When the temperature dropped to 30C, add citric acid 1.5kg while stirring. The reaction was 3h. Adjust the pH to 9-10 with KOH dilute solution, that is, fatty acid salt waterproofing agent. . Diluted with water when used.
1.6 Foam polymer modified rosin soap blowing agent, homemade.
2 Causes and Influencing Factors of Cracks in Thermal Insulation Waterproofing Boards 2.1 Causes of Cracks Rigidity of waterproof rigid boards is a common problem, especially light weight aggregates (insulation materials). There are many causes of cracks, mainly caused by shrinkage. There are several types of shrinkage produced by waterproof mortar: Self-shrinkage. Refers to the macro-scale deformation of the mortar in the hardening stage at a constant temperature and exchange with the outside world. It is generally believed that self-shrinkage of mortar is mainly caused by capillary tension caused by internal self-drying caused by cement hydration.
Carbonized shrinkage. In the atmospheric environment, carbon dioxide chemically reacts with cement hydrates in the presence of moisture to produce CaCQ and free water, which causes shrinkage H. Dry shrinkage (shrinkage). The hardened mortar loses the volumetric deformation caused by the adsorbed water of the internal pores and the gel pores in the unsaturated moist air.
Temperature contraction. Shrinkage due to a decrease in the temperature of the mortar. Cement hydration raises the temperature inside the mortar, and the volume expands, but the surface heats up quickly, the temperature is low, and the volumetric expansion is small. This inconsistent expansion creates tensile stress on the surface and internal compressive stress. When the tensile stress exceeds the tensile strength of the mortar, cracks are generated, which are generally superficial or shallow. The temperature difference between inside and outside, the temperature difference between morning and evening, and the sharp drop in temperature may occur at the same time. The superposition of these several kinds of effects may result in complete fracture of the structural section.
In addition to the above shrinkage deformation, there is chemical shrinkage.
2.2 Influencing factors of cracks It was found that the effect of water-cement ratio on shrinkage was small at 0.354.5.
Aggregate effect. Tests have shown that the dry shrinkage of the mortar decreases almost linearly with increasing aggregate content.
Effects of chemical admixtures (bulking agents, water reducers). The water reducing agent can significantly reduce the dry shrinkage of the mortar. The reason for the shrinkage is that the water reducing agent can significantly reduce the surface tension of the aqueous solution. The swelling agent itself or reacts with certain components in the cement to produce a hydrated calcium sulfo-aluminate (Earwinite) or calcium hydroxide having a micro-expansion effect, which produces a controlled expansion under constraint conditions and establishes a prestressing force. The mortar's compressive strength and tensile strength have increased significantly.
Fly ash effect. Compared with flyash-free mortar, fly ash-containing mortar has less dry shrinkage than flyash-free mortar at the same water-cement ratio.
The impact of the construction environment. Environmental factors such as temperature, humidity, and wind speed play a key role in dry shrinkage. Dry shrinkage is unavoidable due to moisture loss in cement mortar after hardening.
3 Measures to prevent cracks Based on the above causes of cracks and influencing factors, the following measures should be taken to prevent and eliminate cracks in the production and construction of waterproof insulation boards.
Adding water-reducing agent, reducing the amount of cement, reducing the heat of hydration, slowing down the hydration rate or adding slow retarding water reducer, and slowing down the pouring speed, this experiment adopts the lignin-based MNC-MT water-reducing agent.
Adding fly ash and adding activator M at the same time reduce the amount of cement, significantly postpone and reduce the amount of heat, and lower the temperature.
The expansion agent UEA is added to prepare a compensation shrinkage mortar to partially or completely offset the shrinkage stress generated in the mortar by the shrinkage shrinkage and shrinkage shrinkage to prevent or reduce the occurrence of temperature and shrinkage cracks.
Reduce the temperature of the molds such as cement, and place the shade in the raw materials yard, while avoiding construction during high temperature.
The surface treatment of the mortar is carried out. After the initial setting of the mortar, the mortar is compacted before the final setting, and the surface paste is beaten to close the closed water crack and eliminate the early plastic cracks.
Do wet conservation, after the mortar surface treatment, timely coverage, spray water conservation, in order to control the temperature difference between inside and outside, slow down the cooling rate and surface water evaporation rate. Wet curing is not less than 7 days, and then covered with plastic film and then cured for 7 days. Properly extended mold removal time, so that the mortar tensile strength is increased, to improve the crack resistance, reduce the mortar temperature gradient, generally should be removed after 20d.
Avoid construction in bad weather such as high temperatures, low humidity, and high wind speeds to prevent the surface of the mortar from evaporating too quickly. Inconsistent internal and external shrinkage.
Set up the necessary vertical and horizontal splicing (ie temperature expansion joints) on the roof, and the vertical and horizontal splicing gap shall not be less than 3m to prevent irregular cracks to adapt to the deformation of the roof. Slot width 15mm shall be caulked with ointment or asphalt hemp.
4 Conclusion Roof insulation board waterproof thermal insulation and waterproof in one, light weight, insulation and waterproof effect is good, the construction is simple, compared with the traditional insulation and waterproof layer 2 construction cost is low. Its properties are: density 567kg/m3, thermal conductivity 0.10WKm*K), compressive strength 1.72MPa, water impermeability at 0.02MPa for 20d, heat resistance, oxidation resistance, radiation resistance and other properties superior to polymer materials. The construction of some measures to avoid the rigid insulation board cracks.
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