Determination of the optimal replacement content of Portland cement by stone powder using particle packing methods and analysis of the influence of the excess water on the consistency of pastes

Abstract

Cement is considered the basic component with the highest environmental impact in construction, in terms of CO2 emissions. As for the aggregates, the process of comminution of rocks, in addition to artificial sand, generates stone powder that ends up being stored outdoors, generating environmental damages. Thus, the replacement of cement by stone powder appears as an attractive alternative towards the sustainable concretes. In this context, the objective of this paper is to determine the maximum packing density in Portland cement, silica fume and stone dust pastes, to determine the optimal cement substitution content for the stone powder. In addition, it is intended to verify the influence of excess water on the consistency of the mixtures produced. The substitution was done in contents equal to 0%, 7%, 14% and 21% by volume and, for each content, the packing density was determined analytically by CPM model and combinations were reproduced experimentally. Excess water was checked by the mini Kantro cone test. The results showed that the higher cement substitution content of the stone powder obtained the higher packing density, experimental and analytical, and the higher workability, allowing economic and environmental advantages. Analyzing each material, the stone powder resulted in the highest packing density and silica fume is the lowest one. Therefore, finer particles resulted in lower packaging densities, due to the greater specific surface area, which demands more water. The agglomeration resulted in more empty gaps between the grains. In addition, mixtures flowability increased with the increase of the stone powder content. As the excess water is responsible for mixture lubrication, a higher packing density for a given volume of water improves the flowability.

Comparison of the Silica Fume Content for High-Strength Concrete Production: Chemical Analysis of the Pozzolanic Reaction and Physical Behavior by Particle Packing

“…On average, the CPM 34 results were 4.6% higher than the experimental results. Similar values were found in the literature when the same model was used 23,41 . The average results obtained for the CIPM 18,35 were 7.8% higher than the experimental results.…”

“…Klein et al 40 obtained a packing density of 0.559 in cement paste with 12% SF and 0.5% superplasticizer. Moreover, the highest packing density obtained by Campos et al 41 was 0.621 in cement paste with 18% SP, 8% SF and 0.9% superplasticizer.…”

“…Klein et al 40 reached the maximum packing density for the PC of 0.534 without superplasticizer, 0.561 with 0.5% superplasticizer, and 0.599 with 1% superplasticizer. Campos et al 41 obtained a packing density of 0.610 for PC, with 0.9% of superplasticizer. It should be noted that, for the PC, when the w/f ratio is lower than 0.16, the amount of water in the mixture is insufficient to wet all the component particles.…”

Measuring packing density and water demand of Portland cement and SCMs by the mixing energy method

“…Values of the packing density of Portland cement are similar to those found in the literature: Wong and Kwan [11], using the originally proposed method, obtained a packing density of 0.622 in the presence of a chemical admixture [29]. Similar values for packing density were founded by Campos et al [52] for Portland cement (0.610) and silica fume (0.354) using the wet method in the presence of chemical admixtures.…”

Effect of the water/binder ratio on the hydration process of Portland cement pastes with silica fume and metakaolin

“…Numerous researchers investigated the effects of these SCMs in the performance of cementitious materials such as cement pastes, mortars, and concretes [2]- [4], [7], [9], [11]- [15], [16]- [19]. The mineral additions cause influence on the hydration kinetics of cement Portland, and through chemical activity, forms secondary hydrated products.…”