The use of natural sepiolite fiber in concrete

Abstract

To determine the effect of sepiolitic fibers on the characteristics of fresh and hardened concrete, i.e., slumping, density, air content, ultrasonic pulse velocity, freeze-thaw, compressive strength, bending and splitting, tensile strength tests were conducted by the addition of de-fibered sepiolite to the cement in ratios of 0.5 %, 1 %, 2 % and 3 % of mass fractions. The fibers support higher slumping for fresh concrete and increased workability. Samples with 1 % and 3 % addition have similar compressive strength values to the reference series after 28 d. The bending strength of the 2 % added sample is closer to the bending strength of the 28-days reference concretes; however, it is reduced for 0.5 %, 1 % and 3 %. For all the reinforcement ratios the splitting strength increased. The highest impact strength performed for a 3 % reinforcement sample increased by 29 % and scanning electron microscopy (SEM) investigations reveal that the white sepiolite fibers are dispersed homogenously in the concrete, and therefore it, reinforce especially at the interface of the aggregate cement paste by increasing durability. Keywords: sepiolite fiber, mechanical activation, fiber reinforced concrete.Za dolo~itev vpliva sepiolitnih vlaken na zna~ilnosti sve`ega in strjenega betona so bili izvedeni; razlivanje pri padcu, gostota, vsebnost zraka, hitrost ultrazvo~nega impulza, zmrznjenje in odtajanje, tla~na trdnost, upogibanje in cepilno natezna trdnost z dodatkom razvlaknjenega sepiolita betonu v masnih dele`ih 0,5 %, 1 %, 2 % in 3 %. Vlakna pospe{ujejo razlivanje sve`ega betona in izbolj{ajo njegovo oblikovalnost. Vzorca z dodatkom 1 % in 3 % sta pokazala podobno tla~no trdnost kot referen~na serija po 28 d. Upogibna trdnost pri vzorcu z 2 % dodatka je zelo blizu upogibni trdnosti referen~nega betona po 28 d; vendar je manj{a pri dodatkih 0,5 %, 1 % in 3 %. Pri vseh dodatkih pa je cepilna trdnost narasla. Najvi{ja udarna`ilavost izvedena pri vzorcu s 3 % dodatkom je narasla za 29 % in preiskava z vrsti~nim elektronskim mikroskopom (SEM) je odkrila, da so bela sepiolitna vlakna homogeno razpr{ena v betonu, zato oja~ajo stik agregata s cementno pasto in pove~ajo trajnost betona. Klju~ne besede: sepiolitna vlakna, mehanska aktivacija, z vlaknom oja~an beton

The influence of sepiolite on the self-healing capability of concrete by means of water permeability

“…It is known for its low specific gravity and high porosity. Some studies show that using 2% [13] and 10% [14] sepiolite as a cement replacement resulted in mechanical strength improvement of mortar. Sepiolite has also been used as a carrier for bacteria cells immobilized, presenting more efficiency in the self-healing efficiency [15,16].…”

“…Sepiolite has also been used as a carrier for bacteria cells immobilized, presenting more efficiency in the self-healing efficiency [15,16]. By filling the cavities in the cement mortar, sepiolite improves the compressive and bending strengths of the mortar, resulting in positive impacts on the compressive and bending strengths [13,14].…”