Use of Bentonite and Organobentonite as Alternatives of Partial Substitution of Cement in Concrete Manufacturing

Abstract

In order to study the capacities of a new occurrence of Brazilian clay samples as partial replacements of cement, a bentonite sample was selected for utilization in the natural and modified forms for present study. The natural bentonite (BBT) was modified by anchorament of 3-aminopropyltrietoxisilane (BBT APS ) and 3,2-aminoethylaminopropyltrimetoxisilane (BBT AEAPS ) in the surface of component minerals of bentonite sample. The original and organo-bentonite samples were characterized by elemental analysis, scanning electron microscopic and textural analyses. The values of micropore area were varying from 7.2 m 2 g -1 for the BBT to 12.3 m 2 g -1 for the BBT AEAPS . The bentonite samples were characterized by the main variable proportion of bentonite in the natural and intercalated forms (2, 5, 10, 15, 20, 25, 30, and 35 % by weight of cement) in the replacement mode whiles the amount of cementations material. The workability, density of fresh concrete, and absorption of water decreased as the substitution of ordinary Portland cement by perceptual of natural and modified bentonite increased. The results reveal that workability decreased with decrease of the amount of natural bentonite in the concrete, same behavior is observed for bentonite functionalized, varying from 49 to 28 mm. The energetic influence of the interaction of calcium nitrate in the structure of blends was determined through the calorimetric titration procedure.

Influence of Bentonite on Mechanical and Durability Properties of High-Calcium Fly Ash Geopolymer Concrete with Natural and Recycled Aggregates

“…Bentonite is an alumino-phyllosilicate clay, comprising mainly montmorillonite minerals and usually formed by the chemical weathering of volcanic ash in the presence of water. The use of bentonite clay as a partial replacement of cement in conventional concrete containing both natural and recycled coarse aggregates has been widely reported [36][37][38][39][40][41][42][43]. The industrial bentonites are generally either the sodium or calcium variants.…”

A Step towards Sustainable Self-Compacting Concrete by Using Partial Substitution of Wheat Straw Ash and Bentonite Clay Instead of Cement

“…When more bentonite clay can be observed in the concrete mix, less water is available for lubrication, and, therefore, the slump flow and slump T50 values decrease [26]. Moreover, due to the larger surface area of bentonite clay, more cement paste is required to reduce the internal friction between the fine and coarse aggregate [27]. The slump flow and slump T50 values of all of the mixes of bentonite clay and wheat straw ash fell within the limits that define the technical specification for self-compacting concrete and showed good filling ability [1].…”

“…However, at higher a dosage of bentonite clay (BC) (20% of the total weight of the cement), the strength decreased due to the dilution effect, which leads to an alkali silica reaction as a result of the higher quantity of unreactive silica available as a consequence of the high quantity of bentonite clay (BC). Moreover, at a higher dosage of bentonite clay (BC), the compaction process became more difficult due poor workability, resulting in less compressive strength [27].…”

“…The additional binder produced by the bentonite clay (BC) reaction with available lime allows bentonite clay (BC) concrete to continue to gain spilt tensile strength over time. However, at the higher dosage bentonite clay (BC), the compaction process became more difficult due to the lack of workability, which resulted in porous concrete with lower strength [27].…”

“…This is due to the dilution effect, i.e., a smaller amount of CH (calcium hydroxide) available to react with SiO 2 (present in BC and WSA) in order to form C-S-H (calcium-silicate-hydrate). Excess silica causes the alkali silica reaction, and results show that strength begins to decrease [27]. Moreover, at higher dosages of BC and WSA (20% of the weight of the cement), the workability also decreases; thus, further efforts regarding compaction are required to reduce void content that results in porous concrete with less strength [25].…”