Determining Reactivity Level of Granite Aggregate for Concrete

Abstract

Granite rubble is one of the most frequently used aggregates in concrete manufacturing. Granite rubble is considered to be a non-reactive aggregate, however, depending on the quarry, granite may have various impurities including harmful minerals containing active SiO2. The alkalisilica reaction is among the chemical reactions that have a significant effect on the durability of concrete. During the alkalisilica reaction certain forms of silica present in concrete aggregates react with high alkali content leading to formation of hygroscopic gel that expands in humid environment and slowly, although strongly enough degrades concrete structures. Concrete rubble of 3 different fractions was used for the test: 2/8 (Mix D); 11/16 (Mix E); 5/11 (Mix G). The tests revealed that granite rubble used for the tests contained few reactive rocks containing amorphous silica because after 14 days the expansion did not exceed 0.1 % ((D Mix expanded by 0.059 %, E Mix expanded by 0.066 %, G Mix expanded by 0.079 %) according to RILEM AAR-2 test method. After 56 days of testing none of the test specimens demonstrated significant micro-cracking and scaling specific to alkali corrosion; only gel deposits on the surface were observed.

Experimental Study on Compressive Strength and Flexural Rigidity of Epoxy Granite Composite Material

“…Crushed granite is an intrusive volcanic rock (igneous rocks) that consists mainly of orthoclase, quartz, and mica with coarse crystalline grains [16]. Granite rubble is considered to be a non-reactive aggregate, however, depending on the quarry, granite may have various impurities including harmful minerals containing active SiO₂ [17] . The used coarse and fine granite powder was brought from the Aswan area in southern Egypt, which generated from quarrying and mining granite rock.…”

Durability Behavior of Mortars Containing Perlite Tailings: Alkali–Silicate Reaction Viewpoint

“…Alkali-aggregate reactions occur between alkalis (Na 2 O and K 2 O) present in Portland cement and reactive aggregates in the presence of high moisture (80-85%) and adequate temperature beyond the pH [21,22]. An expansive gel is among the main products of AARs.…”

“…An expansive gel is among the main products of AARs. Such a gel absorbs water, swells, and leads to the appearance of cracks and consequent collapse of the cement matrix [22][23][24]. AARs can be classified into three types: alkalisilica, alkali-carbonate, and alkali-silicate reactions [25].…”