Mortar of lime and natural cement for the restoration of built cultural heritage
Abstract
The cultural heritage built in Algeria shows the diversity and the durability of building materials in use. The need to restore the archaeological monuments requires the use of the long-lasting, successful and compatible materials used by former builders. We propose in this study the exploitation of the natural cement as an addition in the formulations of mortars of restoration.
Samples were developed with air lime with the addition of (5%, 10% and 15%) natural cement. The results of analysis of the physical and mechanical characteristics showed an improvement of the properties of elaborate mortars.
The content of 10% of addition gave better results in terms of absorption (16.60%) and mechanical resistance to the compression (1.62 MPa) and to the flexion (0.10 MPa), with regard to the other percentages, it indicates a compatible use with the restoration in old buildings.
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Introduction
The mortar is one of building materials used to show solidarity of elements between them, assure the stability of the work and fill chinks between the blocks of construction. Generally, the mortar consists of a sociable disposition (binder), an aggregate (grease remover), an addition and a water [ 1,2 ].
To obtain hydraulic and resistant mortars, the former (old) builders used some lime, some sand with addition of pozzolana and the plundered brick [ 3 ]. The natural cement discovered at the beginning of the 19th century by Louis Vicat, brings to mortars of lime, the short-term resistance and limits its retreat (withdrawal) without disrupting (perturbing) so much the character to let inhale the walls of construction of old (former) buildings [4]. The various civilizations which followed one another in Algeria, the imprint of their buildings is marked well by the difference of materials used in the constructions.
Our work is aimed at developing mortars of air lime of Ghardaia with the use of natural cement (quick) as addition with different percentages (5, 10 and 15%). Two other mortars were developed as references, the first one consists of 100% of air lime and the second contains 100% of natural cement as sociable disposition (binder). The comparison between the physical and mechanical results (profits) [5 ] of various types (chaps) of elaborate mortars showed that the addition of 10% of natural cement gave better results with regard to (compared with) the other percentages as for the absorption, the retreat (withdrawal) and the mechanical resistance in the compression and in the flexion.
These results (profits) allow the use of natural cement as an addition in mortars of lime to improve certain physical and mechanical characteristics, while keeping the compatible character with former buildings. To widen the interval of addition of natural cement for various contents will allow to encircle better the behavior of this hydraulic sociable disposition(binder) in the restoration( catering) of historic monuments [6].
Conclusion
The values of the physical and mechanical characteristics fléxion, various compositions developed at the level of the laboratory are very close, which shows that the addition of the natural cement is very compatible with the use (custom) in the former (old) buildings.
The content of 10 % of added natural cement gave the physical and mechanical better results with regard to the other 5 % additions and 15%. The mortar containing 100 % of natural cement gave better one value of absorption of water (15.52%) and a mechanical resistance in the compression (5.61Mpa which is upper to the other compositions. This shows that the addition of the natural cement improves the physical and mechanical characteristics of the mortar and confers him a use in the former built, particularly as mortar of damp-proofing filler or terrace.