Effect of surface treatment of apricot shell on the performance of lightweight bio-concrete

Abstract

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Use of Mixed Microbial Cultures to Protect Recycled Concrete Surfaces: A Preliminary Study

“…One measure that may be adopted to enhance concrete durability is the use of surface treatments in situ, the application of coatings and impregnation treatments [ 25 ] that may be of utility in conjunction with new types of concretes, produced with innovative materials. Some examples are the use of apricot shell [ 26 ], graphene oxide [ 27 ], bio-deposition [ 28 ] or silane-based products [ 29 ]. These surface treatments aim to prevent deterioration and damage when exposed to extremely aggressive environments, and to further extend service life [ 21 ].…”

The Properties of Lightweight Aggregates Pre-Coated with Cement Pastes and Their Suitability for Concrete

“…There are many technologies used for aggregate impregnations. In order to increase the aggregate tightness, depending on its type, it may be coated with e.g.,: cement paste [ 21 , 22 , 23 , 24 , 25 , 26 ], natural and synthetic polymers [ 21 , 24 , 27 , 28 , 29 , 30 , 31 , 32 ], calcium metasilicate [ 33 ], sodium silicate [ 22 , 24 , 30 ] or sodium carbonate solutions [ 34 , 35 ], kerosene, different oils [ 24 ], paraffin [ 18 , 31 , 36 , 37 , 38 , 39 ]. It should be stated that in some research, the priority goal of LWA immersion in paraffin or polyethylene glycol is not so much to make concrete tighter but to incorporate the phase change material into the composite in order to improve its thermal properties [ 31 , 36 , 37 ] or freeze-thaw resistance [ 39 ].…”

“…Generally, the impregnation process of a lightweight aggregate may lead to a lower cement content, stabilization of concrete workability, decrease in concrete water absorption, shorter time of element/structure drying out, the increase in concrete durability, strength, thermal, and acoustic insulation [ 24 , 25 , 28 , 29 , 30 , 31 , 32 , 33 , 36 ]. On the other hand, LWA pre-coating may affect the higher concrete density, lack of internal curing with water accommodated in aggregate, higher autogenous shrinkage, and higher rate of drying shrinkage, leading to a worse bond between aggregate and cement paste [ 24 , 31 , 33 ]. It should be stated that qualitative and quantitative effectiveness of LWA impregnation is strongly determined by the type of aggregate as well as the type of impregnant and procedure of pre-coating, since these parameters dictate the mechanism of cement paste absorption.…”

“…The idea of the impregnation of lightweight aggregates [ 22 , 24 ] or recycled concrete aggregates (RCA) [ 21 , 22 , 23 , 26 ] with cement paste seems to be less popular than pre-coating the aggregates with polymers [ 21 , 24 , 27 , 28 , 29 , 30 , 31 , 32 ]. There are probably some concerns regarding less effective impregnation with cement paste in concrete tightness enhancement, higher increase in density, or slightly longer procedure of preparation.…”

“…Unfortunately, there is little comparative research on the effectiveness of various impregnants used for the pre-coating of lightweight aggregates. The examples of such valuable research are [ 24 , 25 ], focused on the comparison of effectiveness of impregnation of natural organic lightweight aggregate with different materials. It was proved that impregnation of LWA with cement paste may be more effective in the reduction of concrete water absorption in comparison to pre-coating the lightweight aggregate with sodium silicate solution, white latex solution, and wood oil.…”