Dry-mixed mortar is usually called hydraulic cement-mixed mortar, which refers to the physical mixing of dried and screened aggregates (such as quartz sand), inorganic cementitious materials (such as cement) and additives (such as polymer HPMC) in a certain proportion A granular or powdery form. The material that is transported to the construction site in the form of bags or bulk, and can be used directly after mixing with water.
The mortar feels rough when used
For dry-mixed mortar produced by artificial sand, the maximum particle size of the sand is generally less than 3.5mm, far less than the standard 4.75mm. During construction, the workers felt that the mortar was still thick. In fact, the roughness was mainly due to the poor workability of the mortar and poor construction. It appears that there are many large particles. The main reason is that the particle gradation of the artificial sand is not good. It is often the phenomenon of “more at both ends and less at the center” of the sand. It is necessary to supplement the sand in the center area.
Plastering mortar cracking hollow drum
Mortar cracking is divided into plastic cracking and shrinkage cracking.
Plastic cracking refers to the cracking of the mortar before or during the hardening process. It generally occurs in the early stage of mortar hardening. The cracks are generally thicker and the crack length is short. Dry shrinkage cracking refers to the cracking of the mortar after hardening. In the later stage of hardening, the cracks are characterized by thin and long.
The main reason for plastic cracking is that the shortening stress occurs in the plastic state due to the rapid loss of water dispersion shortly after the mortar is plastered. When the shortening stress is greater than the bond strength of the mortar itself, cracks occur on the surface. It is often related to the material properties of the mortar and the ambient temperature, humidity and wind force. The greater the amount of cement, the smaller the sand fineness modulus, the higher the mud content, the greater the water consumption, the poorer the water retention of the mortar, and the more prone to plastic cracking of the mortar. Shrinkage cracking is mainly due to the large amount of mortar and cement, high strength, resulting in volume shortening, insufficient post-maintenance of mortar, large drying shrinkage value of mortar admixtures or additives, cracking of the wall itself, improper interface treatment, and indiscriminate use or wrong use of mortar labels. The difference between the elastic modulus of the substrate and the mortar is too large.
The moisture content of the sand in the raw materials of the dry-mixed mortar production enterprise did not meet the standard requirements, the mortar mixing time was too short, and the mixing was uneven, and the construction enterprise failed to arrange the dry-mixed mortar silos and mixers in time according to the dry-mixed mortar construction requirements.
The mortar surface will show air bubbles soon
(1) The adaptability of additives and cement is not good, and bubbles occur.
(2) The sand fineness modulus is too small or the particle gradation is not good, resulting in too high porosity.
The hpmc produced by LANDCEL for dry-mixed mortar has high purity, excellent viscosity and obvious application effect. If you have demand, please consult us for free samples.