North Carolina Building Contractor License Practice Exam

When is it adequate to use a controlled low-strength material?

1. For very short spans

2. For depths below fill

3. On shallow foundations

4. For lightweight structures

The correct answer is: On shallow foundations

Controlled low-strength material (CLSM) is typically used in situations where traditional concrete might not be ideal due to constraints such as weight, stiffness, or the need for easy excavation. The use of CLSM is particularly suited for shallow foundations because it provides adequate support while also being lighter than traditional concrete, which reduces settlement issues. Shallow foundations often require materials that can fill voids without adding excessive weight, making CLSM an ideal choice. Furthermore, shallow foundations might be used where there is limited depth for soil bearing or where there is concern about the additional load from the material itself. CLSM can achieve the necessary strength while also allowing for easy placement and subsequent adjustments or excavation if needed. The adaptability of controlled low-strength material makes it particularly advantageous in these applications, ensuring structural integrity and compliance with building practices. In contrast, using it for very short spans, depths below fill, or lightweight structures might not utilize the unique properties of CLSM to their fullest extent, as these scenarios can often accommodate standard materials without the specific benefits that CLSM provides.