Investigations on Flexural and Compressive Strengths of Mortar Dedicated to Clinker Units—Influence of Mixing Water Content and Curing Time

Jan Kubica,Iwona Galman

doi:10.3390/ma15010347

Abstract

The article presents laboratory tests on the impact of the mixing water content used in the preparation of fresh mortar on the flexural and compressive strength of one of the dry-mix mortars produced by a leading European producer and dedicated to bricklaying with clinker elements. The development of these parameters in relation to curing time was also analyzed. The mortar samples were prepared from a factory-made mortar mix using 4.0 L (the value recommended by the mortar manufacturer), 4.5 L, and 5 L of water per 25 kg bag of ready-made, pre-mixed dry mortar mix. All samples were tested in five series after 5, 9, 14, 21, and 28 days of sample curing. The results of these tests showed that the use of 6 and 18% more mixing water than recommended by the manufacturer (4.5 and 5 L per bag) adversely affected the basic mechanical parameters of the tested mortar. Moreover, it was found that the highest compressive strength values were obtained after 21 days of curing and not after 28 days as usual. It was also found that hardening time and higher than recommended water content adversely affected the bending strength of the mortar.

Highlights

The correct selection of the mortar for a specific type of masonry and its proper preparation has a significant impact on the behavior of a structural element or even the entire structure
These material tests of the mortar were performed in order to determine the effect of the amount of mixing water used on the values of basic mechanical parameters, i.e., compressive strength and flexural strength
In the case of determining the compressive strength of the mortar on the halves of the beams taken from bending tests, apart from the average values of the maximum compressive force Fav and the compressive strength fc,av, the values of coefficient of variation (CoV) νL were calculated and presented

Summary

Introduction

The correct selection of the mortar for a specific type of masonry and its proper preparation has a significant impact on the behavior of a structural element or even the entire structure. It is very important to ensure that the mortar has both appropriate mechanical parameters (compressive and bending strength) and appropriate workability for a period of time that allows its wear, especially in periods of elevated external temperatures (e.g., in summer) or when it is necessary to make prefabricated façade wall panels This usually requires the use of more mixing water than recommended. According to the manufacturer’s information, the prepared mortar should be used within These material tests of the mortar were performed in order to determine the effect of the amount of mixing water used on the values of basic mechanical parameters, i.e., compressive strength and flexural strength. 1.1.Determination flexural strength: dimensions ofbeam-specimens the beam-specimens and scheme; static

Determination of flexural strength:

Mechanism of Cracking

Mode of failure thespecimen: beam specimen:

Test Results and Discussion

L of to compressive strengthstrength as a function of curing

Conclusions