Analysing the logistics impact on the cost composition of a mechanised spraying process of rendering mortar

Brandstetter, Maria Carolina Gomes de Oliveira; Carasek, Helena; Siqueira, Rainiere

doi:10.1590/s1678-86212018000200245

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Tecnologia das Argamassas • Ambient. constr. 18 (2) • Apr-Jun 2018 • https://doi.org/10.1590/s1678-86212018000200245 copy

Analysing the logistics impact on the cost composition of a mechanised spraying process of rendering mortar

Análise do impacto da logística na composição do custo do sistema de projeção de argamassas para revestimento

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

The process of mortar mechanical projection has been approved in terms of its performance, but industrial management knowledge should be applied to understand the economic viability of the system. The aim of this paper is to evaluate the productivity and logistics impact of the mechanised spraying process of rendering mortar on its global cost composition. On a worldwide scale, there are no studies that correlate logistics, productivity and costs for mortar rendering systems, indicating the originality of the research. A multiple case study was proposed. A comparison was made between the manual application and mechanical projection methods of internal wall plastering. The data collection included identifying logistic bottlenecks, studying productive times, lead time, productivity, material consumption and losses and cost composition. The results showed that in both systems an impact on logistics occurs around 50% in teams´ productivity indices and global costs. The impact of productivity on indirect costs that reduce execution time and economic feasibility of the projection system is possible due to strategies that translate logistics efficiency.

Keywords:
Mortar; Mechanical projection; Cost; Logistics; Productivity

Company		Permanent		Type of application	Constructor's time in the use of projection	Floor plan area (sqft)	Floor rendering area (sqft)	Wall Density Wall area/floor area
Company		Official	Hodmen	Type of application	Constructor's time in the use of projection	Floor plan area (sqft)	Floor rendering area (sqft)	Wall Density Wall area/floor area
A	A1	5	2	Projection	3 years	5952.4	17351.4	2.91
	A2	5	2	Projection
	A3	4	1	Manual
B	B1	4	1	Projection	8 years	9074	14186.8	1.56
C	C1	3	2	Projection	5 years	250.7	7265.6	2.23

Labour	Material		Equipment
Labour	Manual	Projection	Manual	Projection
. Official. Hodman. Mixing operator . Elevator operator	. CP 32-II E cement . CH I lime . Finely washed sand	Dry-mix mortar	. Rack and pinion lift . 400 L concrete mixer	. Rack and pinion lift . Equipment of mixing and projection

Step	Manual application	Spray system
Operation	10	8
Transportation	24	9
Inspection	6	5
Storage	11	4
Total	51	26

Team	URP Global (mh/sf)	Wor-kers	UPR Productive	UPR Auxiliary	Unproduc-tivity	Loss Produc-tivity	Mortar waste (rate producer)	Mortar waste (standard rate)
Team A1 Spray	0.0830	7	51.7%	35.5%	12.8%	16	11%	-
Team A2 Spray	0.0952	7	62.9%	28.3%	8.8%	19%	26%	-
Team A3 Spray	0.1010	5	49.5%	40.6%	9.9%	21%	-	-
Team B1 Spray	0.0608	5	48.1%	32.9%	19.0%	18%	10%	15%
Team C1 Spray	0.0635	5	48.1%	40.5%	11.4%	12%	3%	25%

Associação Nacional de Tecnologia do Ambiente Construído - ANTAC Av. Osvaldo Aranha, 93, 3º andar, 90035-190 Porto Alegre/RS Brasil, Tel.: (55 51) 3308-4084, Fax: (55 51) 3308-4054 - Porto Alegre - RS - Brazil
E-mail: ambienteconstruido@ufrgs.br

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[1] Maria Carolina Gomes de Oliveira Brandstetter

Escola de Engenharia Civil e Ambiental | Universidade Federal de Goiás | Av. Universitária, 1488, Bloco A, Sala 12, Setor Universitário | Goiânia - GO - Brasil | CEP 74605-220 | Tel.: (62) 3209-6543 | E-mail: mariacarolina.brands@gmail.com

INADEQUATE WATER SUPPLY
Requisites: a) Uninterrupted supply; b) Quantity recommended by the manufacturer (7.5 1 / 40 kg bag); c) Avoid obstruction of equipment
Solutions of construction work "B"	Solutions of construction work "C"
Supply network to the plaster regardless of the other work services	Supply network to the plaster regardless of the other work services
INADEQUATE ENERGY SUPPLY
Requisites: a) Stability of electric current; b) Avoid sudden shutdowns and burning of equipment; c) Avoid nominal voltage drops; c) Prior assessment of equipment distance to energy source to avoid loss of electrical cables
Solutions of construction work "B"	Solutions of construction work "C"
■ 380V three-phase voltage ■ Exclusive power grid	■ 380V three-phase voltage ■ Exclusive power grid ■ Installation of transformers to raise the voltage and lower the current
INADEQUATE SPRAY SUPPLY
Requisites: a) Spraying capacity; b) Launching energy; c) Dosing system; d) Workability; e) Permanent maintenance; f) Equipment flow limit
Solutions of construction work "B"	Solutions of construction work "C"
■ Mixer Plus Standard and PFT (Figure 3) ■ Helicoidal (rotor and stator) ■ Coupled mixer ■ Spray gypsum and mortar ■ Automatic dosage	■ Betomaq and Putzmaster (Figure 4) ■ Helicoidal (rotor and stator) ■ Independent mixer ■ Exclusive for mortar ■ Manual dosage
TYPE OF MORTAR USED
Requisites: a) conventional or dry-mix mortar; b) Granulometry lower than 6mm; c) Usually dry-mix mortar
Solutions of construction work "B"	Solutions of construction work "C"
Use dry-mix mortar bag of 40 kg.	Use dry-mix mortar bag of 40 kg.
LACK OF MAINTENENCE OF THE SPRAY EQUIPMENT
Requisites: a) Periodicity - ordinary maintenance (daily cleaning), preventive (periodic) and corrective (occasional); b) National and imported spare parts; c) Specialized labor; d) Representatives in Brazil and region
Solutions of construction work "B"	Solutions of construction work "C"
■ Imported equipment ■ Maintenance carried out jointly: construction company and contractor ■ There is a representative for parts and labor in Goiania ■ There is more than one piece of equipment in the construction work (three spraying fronts)	■ Imported equipment ■ Maintenance carried out only by the contractor ■ Contractor easily obtains specialized labor for maintenance ■ Contractor has vast experience in using the equipment applied
DISQUALIFICATION AND LACK OF LABOR TRAINING
Requisites: a) Specialized and qualified for the local conditions; b) Partnerships with entities; c) Training; d) Certification; e) Spraying experience; f) Hiring own or outsourced labor (influence on responsibility and control of those involved)
Solutions of construction work "B"	Solutions of construction work "C"
■ Outsourced labor ■ Additional training offered by the construction company ■ It lias many fronts, this requires a greater effort in training	■ Outsourced labor ■ The Contractor has experience and knowledge, a qualified team and is responsible for the training
LACK OF INSTRUCTION FOR THE MORTAR DOSAGE
Requisites: a) Meet the specifications of the manufacturers (which vary by batch); b) Control of the incorporated air, c) Attention to the properties in the fresh state of plasticity and consistency;
Solutions of construction work "B"	Solutions of construction work "C"
■ Automatic dosage done by a device coupled to the spraying equipment (Figure 5)	■ Manual dosage (Figure 6) ■ Constant checking of the manufacturer's specification and the required properties in the fresh state ■ Periodic inspection
LACK OF INSTRUCTION REGARDING THE CONDUCTION OF THE COATING'S CURE
Requisites: a) Periodicity; b) Reduction of porosity and permeability; c) Increase of the bond strength
Solutions of construction work "B"	Solutions of construction work "C"
■ There is no cure	■ Water is sprayed for 3 days after applying mortar using a hose done by the other team
RESTRICTIONS REGARDING THE STOCK AREA OF THE DRY-MIX MORTAR
Requisites: a) Large storage areas in function of the daily high consumption; b) Planning of delivery times; c) Permanent verification of inventories
Solutions of construction work "B"	Solutions of construction work "C"
■ High consumption, it has three service fronts ■ It lias 2 large storage areas in the 2 basements ■ Allow the distribution of the mortar on the fronts at alternative times	■ It lias a stock area for one week (Figure 7) ■ Palletized stock - for 50 bags of 40 kg mortar makes the distribution of mortar in extra hours
DIFFICULTY REGARDING THE MORTAR UNLOADING AND TRANSPORT
Requisites: a) Mechanization; b) Adequate palletizing to allow passage in the elevators and apartments' doors
Solutions of construction work "B"	Solutions of construction work "C"
■ Use of forklift ■ Use of 1 rack and pinion elevator and a crane ■ Use of transpallet trolleys ■ Replacement by a smaller pallet already in the storeroom, adapting to the spans.	■ Use of forklift (Figure 8) ■ Use of 2 elevators: plank type and rack and pinion type ■ Use of transpallet trolleys
TECHNOLOGICAL CONTROL
Requisites: a) Properties in the fresh state: incorporated air and workability; b) Property in the hardened state: tensile strength; c) traceability
Solutions of construction work "B"	Solutions of construction work "C"
■ Conduct tensile bond strength test (Figure 9) ■ Do not trace the application of dry-mix mortar	■ Perform tensile bond strength test (Figure 9) ■ Do traceability of the application of the dry-mix mortar
APPROACH OF THE MORTAR MANUFACTURER TOWARDS THE CONSTRUCTION WORK
Requisites: a) Orientations; b) Control and readiness of deliveries; c) Pallets' adequacy
Solutions of construction work "B"	Solutions of construction work "C"
■ Good relationship with the supplier and manufacturer of dry-mix mortar	■ There was a problem with quality regarding adherence with the first brand of dry-mix mortar used in the construction work. ■ There was no technical assistance from the supplier/manufacturer. ■ There are problems with the variation in water dosage specification.
THICKNESS OF DOTS, CORNERS AND EDGES
Requisites: a) The render thickness (dots) recommended by the NBR 13749 (ABNT, 2003ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 13749: revestimentos de paredes e tetos de argamassa inorgânicas: especificação. Rio de Janeiro, 2003.) standard, up to 20 nun (for internal coatings is closely linked to the coating's direct cost); Note: Upper thickness represents the incorporated loss and may directly impact the comparative relationship between the sprayed plaster x manual plaster.
Solutions of construction work "B"	Solutions of construction work "C"
■ Rationalization of the nonstructural wall (project) (Figure 10) ■ Use of comer-beds and metal portals to avoid corners and edges (Figure 11)	■ It is a demanding project considering corners and edges.