Analysis of common technical indexes of dry powder mortar


Release time:

2016-04-27

Author:

Shandong Xindadi Group

Source:

Analysis of common technical indexes of dry powder mortar

Dry mortar has been widely used at present, but in the application process, some production, use and supervision units of dry mortar some concepts and performance indicators are confused, the following is the main analysis of the following concepts:
Viscosity and strength: the higher the viscosity, the higher the strength. Strength usually refers to the physical performance index of mortar after curing, and viscosity usually refers to the state of mortar after mixing, which is an index in the construction process. There is no necessary relationship between viscosity and strength.
Bond strength and compressive strength: bond strength refers to the role of the mortar on the bottom of the maximum bonding force. There are two kinds of shear strength and tensile (pull) strength. Tensile strength refers to the ability of the mortar surface to resist a tensile force acting perpendicular to the surface; shear strength refers to the strength measured by applying a parallel force.
Compressive strength refers to the maximum value of mortar failure measured by applying pressure, and is generally the cohesive strength of mortar. High bond strength does not necessarily have high compressive strength, and low compressive strength does not necessarily have low bond strength.
Waterproof and water resistance: the concept of waterproof and water resistance is mainly in the putty products, water resistance refers to the material in the water environment performance does not change greatly, waterproof refers to the water can not penetrate. Putty is only the leveling material before the paint is painted, and it does not have and should not have the performance of waterproof material. JG158 "building indoor putty" and construction JG157 "building exterior wall putty" standard only provides for the water resistance of putty, the molding of putty after soaking in water for a certain period of time to observe whether the putty layer changes. However, in the actual application process, some enterprises exaggerate and publicize, saying that they produce waterproof putty, and some users often ask whether the exterior wall putty is waterproof.
Insulation and heat insulation: insulation is the ability of masonry wall materials or products to prevent heat loss in winter and keep room temperature stable. It usually refers to the ability of the enclosure structure (including the roof, exterior walls, doors and windows, etc.) to prevent heat transfer from the indoor to the outdoor in winter, so that the indoor temperature can be maintained properly. Heat insulation refers to the ability of masonry wall materials or products to prevent heat transfer in summer and keep room temperature stable. Generally refers to the ability of the building envelope to insulate itself from the effects of solar radiant heat and high outdoor temperatures during the summer months, thereby keeping its inner surface at an appropriate temperature. China's building energy efficiency design code stipulates that the building energy efficiency indicators in different regions are different, and the difference between thermal insulation and thermal insulation:
(1) The heat transfer process is different. Heat preservation refers to the heat transfer process in winter, usually according to the stable heat transfer to consider, while considering some of the effects of unstable heat transfer; heat insulation refers to the heat transfer process in summer, usually with 24h as the cycle of periodic heat transfer to consider.
(2) The evaluation indicators are different. Thermal insulation performance is usually evaluated by heat transfer coefficient value or heat transfer resistance value. Thermal insulation performance is usually evaluated by the maximum temperature value of the inner surface of the enclosure structure under the condition of outdoor calculated temperature in summer (I. e. hot weather). If the maximum temperature of the inner surface of the enclosure structure is lower than or equal to the maximum temperature of the inner surface of 240mm thick brick wall (I. e. a brick wall) under the same condition, it is considered to meet the thermal insulation requirements.
(3) different structural measures. Because the thermal insulation performance mainly depends on the heat transfer coefficient or heat transfer resistance of the envelope structure, the light envelope structure composed of porous light thermal insulation material has a small heat transfer coefficient and a large heat transfer resistance, so its thermal insulation performance is better. However, due to its light weight, poor thermal stability, easy to be affected by solar radiation and indoor and outdoor temperature fluctuations, the inner surface temperature is easy to rise, so its thermal insulation performance is often poor.
Hydrophobic and waterproof: in the "definition of terms" of the test method for hydrophobicity of thermal insulation materials, it is stipulated as a performance index reflecting the water penetration resistance of the material, which is expressed by the volume percentage of the unpermeable part of the sample after the water is sprayed in a specified manner and a certain flow rate. The water pressure of the water repellent is relatively small, and the waterproof index of the waterproof material is usually tested under a certain dynamic water pressure. Waterproof materials do not necessarily have a hydrophobic effect (water drop effect), and hydrophobic materials do not necessarily have good waterproof performance.
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