A Comparative Study between Concrete Masonry Units (CMUs) and Insulated Concrete Forms (ICFs)

*Nehal Atlam and Mukaddes Darwish* 

### **Abstract**

 This chapter aims a comprehensive comparative study in order to assess the success of a resilient masonry walls system for major successful buildings in the United States and guide for the selection of optimum materials for each building. Many essential parameters, which control building behaviors such as durability, acoustical privacy, structure configurations, fire and wind resistance, material type, energy use, and cost of the assembly have been analyzed. The mentioned analysis is performed on 10 major buildings, for which the data were available. The results of the analyzed data identified the similarities of the used materials. The learning outcomes of these analyses can be used to improve building strategies for the designs of existing buildings and new buildings. A case study in Gulf Coast, Mississippi is investigated. The procedure for selection of this case study can be utilized as the decision criterion for similar cases of resilient walls system design, and as the main essential factor that lead to the optimum way of building these kind of buildings. Principal component analysis (PCA) is used to correlate the commonly used materials within concrete masonry units (CMUs) and insulated concrete forms (ICFs) properties of the resilient masonry walls system.

**Keywords:** concrete masonry units (CMUs), insulated concrete form (ICFs), resilient masonry walls system, masonry, buildings

#### **1. Introduction**

 Within the building industry complexity, there is a growing interest in new technologies that promise to deliver efficiency, cost savings, durability, and productivity increase to the construction projects. Increasingly, new construction method is emerging, and it called resilient masonry walls system. Using sustainable (resilient) masonry walls system in the construction industry provides safe and a healthy environment, durability, fire, flood, and wind resistance. The key success of a resilient masonry walls system for major successful buildings in the United States and guide future depends on selective optimum materials for each building. Concrete masonry units (CMU) and insulated concrete forms (ICFs) are the most versatile products in the construction industry [1, 2]. These products are not diametrically opposite, they have clear overlaps. Despite this, the main differences between CMU and ICF can be defined.

 Although the concrete block was invented in 1830, it was not widely used until the first half of the twentieth century in the United States. In 1937, insulated concrete forms were developed by Swiss inventors August Schnell and Alsex Bosshard. There were no engineering or architectural method of masonry design for buildings until 1950s. Thickness of the walls were being calculated by "Rule-of-Thumb" tables that were presented in building codes and regulations [1–3]. Consequently, walls were very thick and masonry buildings were not economic after three or four stories so that these buildings had to be constructed with steel or RCC frames. Many experimental and theoretical researches have been conducted on different aspects of masonry in developed countries since 1950s [4, 5]. Prior to the 1990s, wood framing was being used for above-grade walls in homes except in some regions of the United States. Concrete walls have begun to receive a larger share of the market for above-grade walls of homes in the last 10 years. According to the estimations of Portland Cement Association, more than 10,000 homes were built in 1997 with insulated concrete forms (ICF) walls [6]. In addition, in the United States market of foundation walls of homes, concrete masonry units (CMU) have an essential percentage. Besides, CMU has been used for a long time in Florida, Texas, Arizona, and other parts of the southern United States for above-grade walls [6]. However, there are often difficulties encountered by home builders converting from a traditional above-grade framing material to CMU walls or ICF walls [7]. Wood is the most used framing material in the US markets so that the comprehension of CMU or ICF construction for above-grade walls is limited [8].

This chapter presents the analysis of using CMU and ICF methods in construction. In this chapter, a multiple parameter, such as energy use, fire resistance, durability, acoustical privacy, indoor air quality, structure/finish, and cost of the assembly are grouped and compared in different regions all over the United States. All these parameters depend on the principle of sustainability which are environmental, social, and economic impacts. Accordingly, this may lead to develop a better and efficient future community by using a construction system that may be resilient.

#### **2. Methodology**

The main aim of this chapter is to analyze and compare 10 major buildings in United States for which the data were available. According to the analysis of the data, similarities in many important parameters were identified, which control building behaviors such as durability, acoustical privacy, structure configurations, fire and wind resistance, material type, energy use, and cost of the assembly. Principal component analysis (PCA) was used for correlating the commonly used materials within concrete masonry units (CMUs) and insulated concrete forms (ICFs) properties of the resilient masonry walls system.

The parameters are selected according to questionnaire survey. A case study in New Orleans, LA is investigated. The procedure for selection of this case study can be utilized as the decision criterion for similar cases of resilient wall systems design, and as the main essential factor that lead to the optimum way of building these kind of buildings. The learning outcomes of these analyses can be used to improve building strategies for the designs of existing buildings and new buildings.

#### **2.1 Main distinctions between CMU and ICF**

 ICFs can be basically defined as concrete wall systems where the forms remain in place. The forms are typically made from polystyrene foam insulation in which concrete is poured. The ICFs provide an insulated structural wall and, depending

*A Comparative Study between Concrete Masonry Units (CMUs) and Insulated Concrete Forms… DOI: http://dx.doi.org/10.5772/intechopen.87836* 

on a particular system, allow the external and internal wall coverings to be held at a medium or medium level without making any modifications to the wall. ICF systems are typically described according to the type of form and form of the concrete wall after curing. ICF forms consist of foam panels or planks that are held together with special ties or foam block systems (**Figure 1**) [9–11].

 CMU is a standard-sized rectangular block which is used for building construction. CMU is one of the most versatile building product available due to the wide variety of appereances, which can be achieved using concrete wall units and it can also serve as a strong backup system for many types of veneer systems. CMU is known to have high fire-resistance, low maintenance, and high durability. Viewed from decades, it is observed that the basic design of CMU has not changed. CMUs are concrete blocks which are made from Portland cement, water, and aggregates such as stone and quartz. These blocks come in various shapes and are solid or hollow, with two or three voids or cores (**Figure 2**) [3, 12, 13].

**Figure 2.**  *Concrete masonry units (CMUs).* 

Both CMU and ICF wall systems attempt to create energy-saving, durable, storm, and fire resilient wall systems. These resilient wall systems should also create a healthy and comfortable environment for the building occupants, where the twomethods part ways are the ease and efficiency of the building process [2–10, 14].

 Insulated concrete foam takes half the time to construct over concrete masonry unit walls. In addition, concrete block walls have very low R-values ranging from 2 to 3, and insulated CMU have R-values ranging from 4 to 14, depending on the blocks thickness and density [15, 16].

Insulated CMU is not widely used in the US which, in many cases, requires CMU walls to be insulated with additional materials and systems. R-values for ICF

 construction vary with the type of ICF and thickness of the foam. An example of an ICF product is the Bautex Wall Assembly. Bautex Blocks achieve an R-value of R-14. ICF structures are esthetically pleasing and provide design flexibility, such as complex architectural contours and curves. But the CMU is not flexible in complex architectural designs (**Table 1**) [6–10, 17].


#### **Table 1.**

*Main distinctions between CMU and ICF methods.* 

#### **2.2 Questionnaire survey**

In this study, the purpose of the questionnaire survey was to determine the significance of the selected construction parameters and using both CMU and ICF methods that control the sustainable building behavior. The proposed analysis is performed on 10 major buildings, for which the data were available, all over the USA.

The buildings are mainly from Washington, Iowa; Urbana, Illinois; River, Texas; Springfield, Ohio; Gulf Coast, Mississippi; and Burnsville, Minnesota. The introduction section of the questionnaire focused on the general information about the requirements of the home they want to live in. The main section of the questionnaire focused on building materials in order to determine the importance of selected parameters [12].

A total of 44 questionnaires were completed in this study. A 5-point Likert-type scale was used for the questionaire—1 stood for "very important for me" and 5 for "not important for me". The distribution of the respondents by construction method is presented in **Figure 3**.

#### **2.3 Parameters of CMU and ICF methods that control behaviors of sustainable buildings**

 Energy use is one of the most important environmental issues and managing its use is inevitable in any functional society. Buildings are the major energy consumers. Building energy use currently accounts for over 40% of total primary energy consumption in the United States and the European Union. Significant energy savings can be achieved in buildings, if they are properly designed, constructed, and operated. For this reason, building energy efficiency can provide key solutions to energy shortages, carbon emissions, and their serious threat to our living environment. CMU and ICF are two choices for wall systems in both commercial and residential construction to take advantage of their mass. Both CMU and ICF are mass walls. The mass walls systems store energy during the day and release it throughout the night. They provide energy efficiency through mass which makes mass walls a good choice in hot and humid climates, where the temperature varies significantly throughout the day [3, 4, 20]. Many important parameters that control *A Comparative Study between Concrete Masonry Units (CMUs) and Insulated Concrete Forms… DOI: http://dx.doi.org/10.5772/intechopen.87836* 

**Figure 3.** 

*Comparison of construction methods used in the survey.* 


#### **Table 2.**

*Comparison between CMU and ICF parameters.* 

building behaviors and material chices such as durability, acoustical privacy, structure configurations, fire and wind resistance, material type, energy use, and cost of the assembly used to identify the similarity by using both CMU and ICF methods in 10 major buildings, for which the data were available, all over the USA. A comparison study between CMU and ICF parameters performed to show the differences between the two methods is given in **Table 2**.

#### **3. Case study: concrete home**

 As an example, a concrete home known as the "Sundberg home" was identified [18]. Hurricane Katrina had slammed in the coastal counties of Mississippi with sustained winds of 125 mph and a storm surge that reached 28 feet. All the homes, in which concrete was used as the main building material, were demolished. Scott and Caroline Sundberg Home, of which 85% was complete, was the only building to survive in the Mississippi coast when the Hurricane hit. This home was built using ICF walls, which are reinforced both horizontally and vertically by concrete columns, post tension concrete slab, and concrete roof on the top of cold rolled metal panel sections. It has spread footings with concrete members in order to distribute the load to the soil. Besides, it has a 4-foot-high beam-wall and a beam-wall down the center. There is connection from the roof down to the third floor, on to the second floor, and then to the carport [18]. The bottom of the beam of the first-floor living space is 25.4 feet above the sea level. The main purposes when building this home was to provide elasticity and to withstand 180 and 200 mph winds. Thus, the concrete home had the power to resist the wind, flood, and achieve the goal to be a resilient building (**Figure 4**).

**Figure 4.**  *Pass Christian, MS, October 4, 2005—aerial photo shows Sundbergs' home after Hurricane Katrina [19].* 

### **4. Results and discussion**

This chapter demonstrates the proposed approach for the resilient walls system in the construction industry. The aim of this study is to choose optimal construction method for buildings from two selected construction systems such as ICF and CMU methods. Mainly, 10 major buildings all over United State have been analyzed and compared. The analysis of the data identified similarity in many important parameters that control building behaviors such as durability, acoustical privacy, structure configurations, fire and wind resistance, material type, energy use, and cost of the assembly. Therefore, the key success of a resilient masonry walls system for major successful buildings depends on selective optimum materials for each building. Finally, this may lead to develop a better and efficient future community by using a construction system that may be resilient.

#### **Author details**

 Nehal Atlam and Mukaddes Darwish\* Civil, Environmental, and Construction Engineering Department, Texas Tech University, Texas, USA

\*Address all correspondence to: mukaddes.darwish@ttu.edu

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*A Comparative Study between Concrete Masonry Units (CMUs) and Insulated Concrete Forms… DOI: http://dx.doi.org/10.5772/intechopen.87836* 

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[20] Photo courtesy of John Fleck. 2018

#### **Chapter 26**
