The problems of the occurrence of efflorescence on the surface of buildings’ exterior walls made of vibropressed concrete blocks and the methods of blocking these processes

Abstract

At this article it has been considered the questions concerning the occurrence of efflorescence on the surface of buildings' exterior walls made of vibropressed concrete blocks. The chemical and mineralogical composition of efflorescences were investigated using the electron-scan microscope and diffractometer. The mechanism of the efflorescence occurrence was disclosed The suitability of hydrophobization as a purifying method of the above mentioned walls from efflorescences was analyzed. The results of full-scale testing of proposed methods are given.

Engineering solutions for heart efficient exterior walls in climatic condition of the Republic of Bashkortostan

“…Crisis events in domestic construction branch, as well as poor engineering solutions and low quality of construction and erection work, poor development of the construction industry in some regions, etc. [6][7][8][9] when making radical changes (adopted in 1995) to regulatory requirements to building heat insulation have caused heat engineering norms to be constantly changed. Recent Russian standards as SP 50.13330.2012 "Building heat insulation" are considering the advanced experience and are more close to real conditions [10,11].…”

Practical Researches to Increase Leaching Resistance on Fine Concrete for Vibropressed Product

“…The mechanism for the removal of potassium, sodium and calcium salts formed during the hydration of cement [9], contained in the cement initially in the form of free oxides, or entering the mixture from the outside, together with ground or rainwaters, divided into two types:…”

“…This type of concrete has not only advantages but a big disadvantage: it is prone to efflorescence, leaching. Scientists have been working on the leaching problem for a very long period, but the problem has not been solved yet [1][2][3][4]. The purpose of our work was to study the mechanism of leaching, identify the causes and find ways to solve this problem, as well as industrial experiment with the use of our theoretical developments.…”

The mathematical model and numerical calculation method of efflorescence

“…Efflorescence refers to the phenomenon which cement hydration product Ca(OH) 2 in the pore solution and the external environment of the molar concentration gradient driven continues to lose and cause of C─S─H gel and ettringite continuous decalcified dissolution, resulting in calcium ion concentration in the pore solution declining, pH continued to decrease, and the hydration products gradually lose gelation when cement‐based materials in soft water or other media environment. For buildings, it is not conducive to the sound insulation performance, fire performance and decoration engineering quality control . The results showed that the Ca(OH) 2 of hydration product had the following relationship with C─S─H. Ca(OH) 2 and C─S─H remained relatively stable when the concentration of calcium ion in the pore solution is high; when the pore solution c (Ca 2+ ) < 20 mmol/L, Ca(OH) 2 begins to dissolve; when the pore solution c (Ca 2+ ) < 4 mmol/L, C‐S‐H begins to decalcification dissolve; when the pore solution c (Ca 2+ ) < 2 mmol/L, the chemical loss of concrete reaches the maximum, and the residue of this stage is the silica gel with no binding properties. …”

“…For buildings, it is not conducive to the sound insulation performance, fire performance and decoration engineering quality control. 8,9 The results showed that the Ca(OH) 2 of hydration product had the following relationship with C─S─H.…”