The Effect of Petrographic Characteristics and Physico-Mechanical Properties of Aggregates on the Quality of Concrete

Abstract

This paper examines the effect of the aggregate type on concrete strength, and more specifically, how the petrographic characteristics of various aggregate rocks as well as their physicomechanical properties influences the durability of C 25/30 strength class concrete. The studied aggregate rocks were derived from Veria-Naousa and Edessa ophiolitic complexes as well as granodiorite and albitite rocks from their surrounding areas in central Macedonia (Greece). Concretes were produced with constant volume proportions, workability, mixing and curing conditions using different sizes of each aggregate type. Aggregates were mixed both in dry and water saturated states in concretes. Six different types of aggregates were examined and classified in three district groups according to their physicomechanical properties, petrographic characteristics and surface texture. The classification in groups after the concrete compressive strength test verified the initial classification in the same three groups. Group I (ultramafic rocks) presented the lowest concrete strengths, depending on their high alteration degree and the low mechanical properties of ultramafic aggregates. Group II (mafic rocks and granodiorite) presented a wide range of concrete strengths, depending on different petrographic characteristics and mechanical properties. Group III (albite rocks) presented the highest concrete strengths, depending on their lowest alteration degree and their highest mechanical properties. Therefore, mineralogy and microstructure of the coarse aggregates affected the final strength of the concrete specimens.factor for the quality of concrete. For the same quality cement, different lithotypes of coarse aggregates characterized by different micro-roughness, mineralogical composition, structure and compressive strength may result in different concrete compressive strength [10,11].Mineralogical composition of the aggregates, and more specifically their alteration degree, strongly influence their mechanical behavior and their in-service performance [10,[12][13][14][15][16][17]. Increased percentages of certain secondary minerals negatively affect the physical, as well as the mechanical properties of aggregates due to their smooth layers, cleavage and platy or fibrous crystal habit [10,17], which have an adverse effect on their performance as concrete aggregates [10]. The increased number of construction failures has highlighted the importance of understanding that mineralogy is a mean to diagnose problems in engineering constructions. The physico-mechanical properties of rocks used as aggregates are the most significant parameters in any application and in their classification for various engineering purposes. Physicomechanical properties depend on the petrographic characteristics (mineralogical composition, texture, size, shape and arrangement of mineral grains, nature of grains contact and degree of grain interlocking), alteration and deformation degree of the source rock [18][19][20][21][22].Nowadays, many researchers [11,[23][24][25]...

Petrographic Characteristics of Sandstones as a Basis to Evaluate Their Suitability in Construction and Energy Storage Applications. A Case Study from Klepa Nafpaktias (Central Western Greece)

“…The diagram in Figure 6c illustrates the interaction of the mechanical properties LA and UCS directly dependent on the grain size. Several researchers have also reported similar relationships between these properties [23,65,69,70] when studying various types of rocks. In this diagram, it seems obvious that the mechanical characteristics of sandstones vary in a similar way under different type of mechanical loadings.…”

“…These satisfactory strength results may attributed to the generally high microtopography of coarse-grained, medium-grained, as well as of fine-grained sandstones relative to the microtopography of other used rocks [22] (Figure 2b,d,f,h and Figure 4). The microtopography of the aggregates constitutes a crucial factor for the mechanical quality of the aggregate rocks and consequently for the quality of the produced concrete as it influences the cohesion and the bonding between the cement paste and the aggregate particles [1,22,23]. The only studied concrete specimen that displays lower strength (25 MPa) than the standard states is the specimen in which the used aggregate was the enriched in carbonate fossils coarse grained sandstone (Figure 2c).…”

“…Many researchers have investigated the correlations between the percentages of specific mineralogical compositions of aggregates and the final compressive concrete strength. Petrounias et al [22,23] when investigating igneous rocks from Greece concluded that the alteration products of serpentinite-bearing rocks and andesitic-intermediate rocks have a profound impact on their mechanical behavior, that apparently affect their ability to be characterized as suitable concrete aggregate material. On the other hand, Yılmaz and Tugrul [21] evaluated sandstone aggregates from Turkey based on the parameters that include: physical properties, mechanical properties and compositional variations.…”

Petrographic and Mechanical Characteristics of Concrete Produced by Different Type of Recycled Materials

“…In general, several researchers, such as Rigopoulos et al [62], have studied the effect of microroughness of various rocks and how it affects their quality as aggregates according to the BS 812 Part 1 [58]. More specifically, Petrounias et al [56,63] who studied various rocks on their suitability as concrete aggregates reported that the microroughness of the aggregate particles plays a determinant role in the quality of the concrete products. Smooth surface constitute determinant negative factor for poor bonding of the aggregate grain and the cement paste and, hence, low concrete strength.…”

An Experimental Study for the Remediation of Industrial Waste Water Using a Combination of Low Cost Mineral Raw Materials

“…Serpentinite comprises abundant and extensive outcrops in several ophiolite complexes in Greece and worldwide, and so therefore its use to remediate analogous quagmires is cost effective. For example, in the Veria-Naousa, ophiolite occurs near the studied Agios Philippos polluted pit lake [20][21][22][23][24]. Furthermore, magnesite has been widely used from several researchers for the remediation of industrial waste waters.…”