Types of mortar and strength classes, difference between cement mortar and mixed mortar

Mortar is a binding substance used in bricklaying on the construction, by a certain proportion of sand and cementing materials (cement, lime paste, clay, etc.) and water and into, also known as mortar, also as mortar. Commonly used mortars are cement mortar, mixed mortar (or called cement-lime mortar), lime mortar and clay mortar.

1.There are several strength classes of mortar

         If it is premixed masonry mortar or cement mortar, it is generally divided into 7 grades, respectively M30, M25, M20, M15, M10, M7.5, M5, if it is cement mixed mortar, it is generally divided into 4 grades, respectively M15, M10,

 M7.5, M5. There are many kinds of mortar types and strength grades on the market, and with different kinds of mortar types and strength grades, the performance, scope of use, price and construction methods will also be different.

 There are many kinds of mortar types and strength grades on the market, different types and strength grades, its performance, scope of use, price, construction methods will be different, when you choose, we must choose

 according to the actual use of the environment, construction needs and other aspects.

1.   The strength of masonry mortar is expressed in terms of strength classes

        The strength grade of mortar is determined by the compressive strength value (in MPa) at the age of 28d measured by the standard test method under the standard curing conditions (temperature (20±2)℃ and relative humidity of 

more than 90%) with the cube specimen with the side length of 70.7mm.

      In general, multi-storey building wall selection M2.5-M15 masonry mortar; mortar strength grade is not fixed, generally affected by the construction process, material quality, modulation ratio and other factors, when the mortar

 impurities or mud and other content of the mortar when the strength of mortar will appear to decline phenomenon, affecting the performance and service life of the mortar.

2.What you need to pay attention to when mixing mortar 

        a.modulation process, should be added to the mortar waterproof powder and other additives, the purpose of doing so is to make the consistency and viscosity of the mortar to be improved. If you want to make the mortar into concrete, you should also pour the right amount of stones into the mortar.

        b.when at modulation, must master the modulation time and mixing, and mixing time can not be too long or too short, if the mixing time is too long, or placed for too long, then it will lead to lime in the mortar is volatilized, resulting in a decline in the strength of the mortar, or cause problems with the process of modulation of the mortar.

3.Difference between cement mortar and mixed mortar

        Performance characteristics of mixed mortar

        a.Very high foaming speed, can produce a large number of foam in an instant, foam large, medium and small three-dimensional uniform matching.

        b.Very high foaming capacity with high energy for instant foaming, rapid foaming and three-dimensional foaming.

        c.Very high foam stabilizing effect, the foam lasts for a long time, the foam persistence and foam stabilization is very good.

        d.It won't harden in winter, won't melt in summer, has a stable state, and can be quickly and evenly mixed with the base powder.

         Definitional differences in mortar

        a.Cement mortar = cement + sand + water. Cement mortar is made by mixing and blending cement and sand in certain proportions, which allows for the preparation of higher strength mortars. Cement mortar is generally used in foundations, basements that have been subjected to water for a long period of time, and masonry that is subjected to high external forces.

        b.Lime mortar = lime + sand + water. The addition of lime (paste) is called “white lime mortar” or “lime mortar”. Lime mortar is a mortar made by mixing lime paste and sand in a certain proportion, and it gains its strength completely by the air-hardening of lime.

        c.Mixed mortar = cement + sand + plaster + water. When cement is added and lime is added, it is called “mixed mortar”. Mixed mortar is generally made of cement, lime plaster and sand, and is generally used for masonry above ground level. Mixed mortar due to the addition of lime paste, improve the ease of plant mortar, operation is more convenient, conducive to masonry compactness and efficiency.

        Simple differentiation of mortar

        a.Look at the color; lime mortar is white, mixed mortar is medium gray, and cement mortar is darker because it is not mixed with white ash.

        b.The early strength of lime mortar is low, but after air-hardening in the air the strength is not so low that a fingernail cannot scratch it.

        c.You can tell by what part of the body it is used on.

        Mixed mortar is generally made by mixing cement, lime paste and sand, and is generally used for masonry above ground level.

        The use of cement mortar, in construction projects, one is the foundation and wall masonry, used as a binder for block masonry materials, such as masonry burrstone, red brick to use cement mortar; the second is used for indoor and outdoor plastering. It can be used alone for masonry and decorative plastering, and can also be made into mixed mortar (such as cement-lime mortar, cement-clay mortar) to apply to different requirements of masonry and plastering projects.

        Difference between cement mortar and mixed mortar

        a.The composition is different:Mixed mortar is generally made of cement, lime paste and sand, and is generally used for above-grade masonry. Mixed mortar is due to the addition of lime paste, thus improving the compatibility of mortar, the operation is more convenient, conducive to masonry compactness and efficiency. Cement mortar is composed of cement, medium sand and water, and the price is related to the proportion of materials.

        b.Water retention is different:Cement mortar is prone to cracking, which is one of the reasons for using mixed mortar instead of cement mortar for interior plastering. In addition, from the appearance point of view, pay attention to see the mortar in the transportation process, cement mortar water retention is not as good as mixed mortar. In the transportation of the bumpy process, there is a layer of water on the surface of the cement mortar (the standard is not high enough to see the sand is not mixed), and mixed mortar and ease and water retention are better than cement mortar.

        c.The intensity varies:Cement mortar is mainly used in wet areas such as basement\foundation\hydraulic works. The same grade of cement mortar and mixed mortar compared to the strength of cement mortar is a little higher, so the specification of the door and window openings to use cement mortar to do corner protection. Mixed cement mortar is made by adding lime, clay and other additives on the basis of cement mortar, mixed cement mortar is plastic, smooth operation, cement mortar is less than mixed water mortar with one kind of lime paste, strength is not high.