A study on the relationship between porosity of the cement paste with mineral additives and compressive strength of mortar based on this paste

doi:10.1016/j.cemconres.2004.07.007

Cement and Concrete Research

Volume 36, Issue 9, September 2006, Pages 1740-1743

https://doi.org/10.1016/j.cemconres.2004.07.007 Get rights and content

Abstract

Mercury intrusion porosimetry study was carried out on ordinary Portland cement (OPC) pastes with 10% to 40% mineral additives, such as steel-making slag, granulated blast furnace slag and fly ash. For all samples, the porosity of paste and compressive strength of mortar based on this paste were determined at 3, 7, 28, 90 and 180 days. Relationship between the porosity and strength was investigated and some equations for the strength–porosity relationship were presented according to Balshin multiplicative model. Results show that mineral additives delayed process that micropore structure of OPC paste developed and strength development of sample with mineral additives was faster than that of OPC sample. Balshin equation fits the results of strength and porosity of all samples and there is a strongly quantitative relationship between strength and porosity. After being mixed with mineral additives, the intrinsic strength σ₀ and power n both increased and the sequence of σ₀ and n for different mineral additives was fly ash>steel-making slag>blast furnace slag.

Introduction

These years' various types of by-product and waste materials, such as fly ash and blast furnace slag, are used as mineral additives in the high-performance concrete, in terms of better workability, higher strength or better durability [1], [2]. There are many studies on the influence of mineral additives on the porosity and strength of ordinary Portland cement (OPC) paste recently [3], [4]. Furthermore, the study on the relationship between porosity and strength of OPC paste without mineral additives has developed for many years [5], [6], [7]. However, the study on the relationship between porosity and strength of OPC paste with mineral additives is still seldom reported. Therefore, in this paper, the effect of steel-making slag, blast furnace slag and fly ash on porosity and compressive strength of OPC paste has been studied and the relationship between compressive strength and porosity has been revealed.

Section snippets

Materials

Ordinary Portland cement and three mineral additives, namely, steel-making slag, granulated blast furnace slag and fly ash, were collected from different sources in China. After examining their chemical and physical properties (Table 1), the mineral additives were mixed with OPC in 10% to 40% quantity on weight replacement basis. Samples were named as: OPC, control sample without mineral additives; STn, OPC with steel-making slag; SLn, OPC with blast furnace slag; FAn, OPC with fly ash, where n

Porosity and strength of OPC sample with mineral additives

The porosity of the OPC paste with mineral additives and compressive strength of mortar based on this paste were listed in the Table 2. There was a decrease in the porosity of all samples with advancement of hydration period, due to the gradual filling of large pore by hydration products of cementitous materials [3], [8], [9]. Porosity of OPC paste had little change after 28 days, while that of OPC pastes with different mineral additives still had an obvious decrease at 90 days, which means

Conclusions

(1)
Mineral additives delayed the process that the micropore structure of the OPC paste developed. Fly ash and steel-making slag increased porosity of the OPC paste at a respective age, while blast furnace slag decreased porosity of the OPC paste after 28 days. Furthermore, the sequence of capacity of filling the large pore was blast furnace slag>steel-making slag>fly ash.
(2)
Strength development of the sample with mineral additives is faster than that of the OPC sample. At 28 days, the compressive

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A study on the relationship between porosity of the cement paste with mineral additives and compressive strength of mortar based on this paste

Abstract

Introduction

Section snippets

Materials

Porosity and strength of OPC sample with mineral additives

Conclusions

Cem. Concr. Res.

Cem. Concr. Res.

Cem. Concr. Res.

Cem. Concr. Res.

Use of fly ash or silica fume to increase the resistance of concrete to feed acids

Mag. Concr. Res.